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tunnel to photograph the model while the wind is on. The photographic results can be digitized to create a full distribution of the external pressures acting on the model, and subsequently mapped onto a computational geometric mesh for direct comparison with CFD results. PSP measurements can be effective at capturing pressure variations across the model however often require supplemental pressure taps on the surface of the model to verify the absolute magnitude of the pressure coefficients. An important property of well behaved PSP paints is they also should be insensitive to temperature effects since the temperature inside the wind tunnel could vary considerably after continuously running. Common difficulties encountered when using PSP include the inability to accurately measure the leading and trailing edge effects in areas where there is high curvature due to limitations in the cameras ability to gain an advantageous viewing angle. Additionally application of PSP on the leading edge is sometimes avoided because it introduces a finite thickness that could cause early flow separation thus corrupting results. Since the pressure variations at the leading edge is typically of primary interest, the lack of accurate results in that region is very problematic. Once a model is painted with pressure sensitive paint, certain paints have been known to adhere and continue to perform for a matter of months after initially applied. Finally PSP paints have been known to have certain frequency characteristics where some require a few moments to stabilize before achieving accurate results while others converge rapidly. In the latter instance paints that have ability to reflect rapid changes in pressure can be used for
Dynamic PSP applications where the intent is to measure unsteady flow characteristics.
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1228:, wind tunnel tests are used to measure the velocity around, and forces or pressures upon structures. Very tall buildings, buildings with unusual or complicated shapes (such as a tall building with a parabolic or a hyperbolic shape), cable suspension bridges or cable stayed bridges are analyzed in specialized atmospheric boundary layer wind tunnels. These feature a long upwind section to accurately represent the wind speed and turbulence profile acting on the structure. Wind tunnel tests provide the necessary design pressure measurements in use of the dynamic analysis and control of tall buildings.
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facility sits. On the other hand, CFD validation still requires wind-tunnel data, and this is likely to be the case for the foreseeable future. Studies have been done and others are underway to assess future military and commercial wind tunnel needs, but the outcome remains uncertain. More recently an increasing use of jet-powered, instrumented unmanned vehicles, or research drones, have replaced some of the traditional uses of wind tunnels. The world's fastest wind tunnel as of 2019 is the LENS-X wind tunnel, located in
Buffalo, New York.
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909:(PIV): PIV is a technique in which a laser sheet is emitted through a slit in the wall of the tunnel where an imaging device is able to track the local velocity direction of particles in the plane of the laser sheet. Sometimes this technique involves seeding the airflow with observable material. This technique allows for the quantitative measurement of the velocity and direction of the flow across the areas captured in the plane of the laser.
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323:, addressed these issues by inventing, designing and operating the first enclosed wind tunnel in 1871. Once this breakthrough had been achieved, detailed technical data was rapidly extracted by the use of this tool. Wenham and his colleague John Browning are credited with many fundamental discoveries, including the measurement of l/d ratios, and the revelation of the beneficial effects of a high
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measurements can be taken from these tests. The aerodynamic forces on the entire object can be measured, or on individual components of it. The air pressure at different points can be measured with sensors. Smoke can be introduced into the airstream to show the path that air takes around the object. Or, small threads can be attached to specific parts to show the airflow at those points.
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870:. The fog is transported inside the wind tunnel (preferably of the closed circuit and closed test section type). An electrically heated grid is inserted before the test section, which evaporates the water particles at its vicinity, thus forming fog sheets. The fog sheets function as streamlines over the test model when illuminated by a light sheet.
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significant application for boundary layer wind tunnel modeling is for understanding exhaust gas dispersion patterns for hospitals, laboratories, and other emitting sources. Other examples of boundary layer wind tunnel applications are assessments of pedestrian comfort and snow drifting. Wind tunnel modeling is accepted as a method for aiding in
373:, is a basic parameter in the description of all fluid-flow situations, including the shapes of flow patterns, the ease of heat transfer, and the onset of turbulence. This comprises the central scientific justification for the use of models in wind tunnels to simulate real-life phenomena. However, there are limitations on conditions in which
1120:" is the total energy of a gas stream, composed of internal energy due to temperature, the product of pressure and volume, and the velocity of flow. Duplication of the conditions of hypersonic flight requires large volumes of high-pressure, heated air; large pressurized hot reservoirs, and electric arcs, are two techniques used.
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stationary. In a wind tunnel test, the road must also be moved past a vehicle along with air being blown around it. This has been accomplished with moving belts under the test vehicle to simulate the moving road, and very similar devices are used in wind tunnel testing of aircraft take-off and landing configurations.
246:: the ratio of inertial forces to viscous forces should be kept. This parameter is difficult to satisfy with a scaled model and has led to development of pressurized and cryogenic wind tunnels in which the viscosity of the working fluid can be greatly changed to compensate for the reduced scale of the model.
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Tempera Paint: Similar to oil, tempera paint can be applied to the surface of the model by initially applying the paint in spaced out dots. After running the wind tunnel, the flow direction and separation can be identified. An additional strategy in the use of tempera paint is to use blacklights to
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was a novel wind tunnel design that allowed for high-speed airflow research, but brought several design challenges regarding constructing a high-speed wind tunnel at scale. However, it successfully used some large natural caves which were increased in size by excavation and then sealed to store large
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The earliest wind tunnels were invented towards the end of the 19th century, in the early days of aeronautical research, as part of the effort to develop heavier-than-air flying machines. The wind tunnel reversed the usual situation. Instead of the air standing still and an aircraft moving, an object
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Wind tunnels are also classified based on their main use. For those used with land vehicles such as cars and trucks the type of floor aerodynamics is also important. These vary from stationary floors through to full moving floors, with smaller moving floors and some attempt at boundary level control
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Sublimation (alternate definition): A flow visualization technique is to coat the model in a sublimatable material where once the wind is turned on in regions where the airflow is laminar, the material will remain attached to the model, while conversely in turbulent areas the material will evaporate
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or geometrical shapes are mounted for study. Typically the air is moved through the tunnel using a series of fans. For very large wind tunnels several meters in diameter, a single large fan is not practical, and so instead an array of multiple fans are used in parallel to provide sufficient airflow.
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Wind tunnel tests in a boundary layer wind tunnel allow for the natural drag of the Earth's surface to be simulated. For accuracy, it is important to simulate the mean wind speed profile and turbulence effects within the atmospheric boundary layer. Most codes and standards recognize that wind tunnel
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By the end of World War II, the US had built eight new wind tunnels, including the largest one in the world at
Moffett Field near Sunnyvale, California, which was designed to test full size aircraft at speeds of less than 250 mph (400 km/h) and a vertical wind tunnel at Wright Field, Ohio,
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was moved to
Auteuil, a suburb of Paris, where his wind tunnel with a two-metre test section is still operational today. Eiffel significantly improved the efficiency of the open-return wind tunnel by enclosing the test section in a chamber, designing a flared inlet with a honeycomb flow straightener
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only) the temperature rise in the airflow. The direction of airflow around a model can be determined by tufts of yarn attached to the aerodynamic surfaces. The direction of airflow approaching a surface can be visualized by mounting threads in the airflow ahead of and aft of the test model. Smoke or
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The development of wind tunnels accompanied the development of the airplane. Large wind tunnels were built during World War II, and as supersonic aircraft were developed, supersonic wind tunnels were constructed to test them. Wind tunnel testing was considered of strategic importance during the Cold
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Air is not always the best test medium for studying small-scale aerodynamic principles, due to the speed of the air flow and airfoil movement. A study of fruit fly wings designed to understand how the wings produce lift was performed using a large tank of mineral oil and wings 100 times larger than
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High-altitude tunnels: These are designed to test the effects of shock waves against various aircraft shapes in near vacuum. In 1952 the
University of California constructed the first two high-altitude wind tunnels: one for testing objects at 50 to 70 miles above the earth and the second for tests
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In the United States, many wind tunnels have been decommissioned from 1990 to 2010, including some historic facilities. Pressure is brought to bear on remaining wind tunnels due to declining or erratic usage, high electricity costs, and in some cases the high value of the real estate upon which the
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at
Langley Research Center in Hampton, Virginia. The tunnel was powered by a pair of fans driven by 4,000 hp (3,000 kW) electric motors. The layout was a double-return, closed-loop format and could accommodate many full-size real aircraft as well as scale models. The tunnel was eventually
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The aerodynamic properties of an object can not all remain the same for a scaled model. However, by observing certain similarity rules, a very satisfactory correspondence between the aerodynamic properties of a scaled model and a full-size object can be achieved. The choice of similarity parameters
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Pressure
Sensitive Paint (PSP): PSP is a technique whereby a model is spray coated with a paint that reacts to variations in pressure by changing color. In conjunction with this technique, cameras are usually positioned at strategic viewing angles through the walls, ceiling, and floor of the wind
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In 1941 the US constructed one of the largest wind tunnels at that time at Wright Field in Dayton, Ohio. This wind tunnel starts at 45 feet (14 m) and narrows to 20 feet (6.1 m) in diameter. Two 40-foot (12 m) fans were driven by a 40,000 hp electric motor. Large scale aircraft
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Sporting equipment has also studied in wind tunnels, including golf clubs, golf balls, bobsleds, cyclists, and race car helmets. Helmet aerodynamics is particularly important in open cockpit race cars such as
Indycar and Formula One. Excessive lift forces on the helmet can cause considerable neck
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The lighting is usually embedded into the circular walls of the tunnel and shines in through windows. If the light were mounted on the inside surface of the tunnel in a conventional manner, the light bulb would generate turbulence as the air blows around it. Similarly, observation is usually done
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The inside facing of the tunnel is typically as smooth as possible, to reduce surface drag and turbulence that could impact the accuracy of the testing. Even smooth walls induce some drag into the airflow, and so the object being tested is usually kept near the center of the tunnel, with an empty
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move air through the wind tunnel, while the object being tested is held stationary. The object can be an aerodynamic test object such as a cylinder or an airfoil, an individual component of an aircraft, a small model of the vehicle, or, in the largest tunnels, even a full-sized vehicle. Different
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of vehicles by reducing the aerodynamic drag. In these studies, the interaction between the road and the vehicle plays a significant role, and this interaction must be taken into consideration when interpreting the test results. In the real world, the vehicle is moving while the road and air are
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Other problems are also studied with wind tunnels. The effects of wind on man-made structures need to be studied when buildings became tall enough to be significantly affected by the wind. Very tall buildings present large surfaces to the wind, and the resulting forces have to be resisted by the
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The US Navy in 1916 built one of the largest wind tunnels in the world at that time at the
Washington Navy Yard. The inlet was almost 11 feet (3.4 m) in diameter and the discharge part was 7 feet (2.1 m) in diameter. A 500 hp (370 kW) electric motor drove the paddle type fan
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For external flow tunnels various systems are used to compensate for the effect of the boundary layer on the road surface, including systems of moving belts under each wheel and the body of the car (5 or 7 belt systems) or one large belt under the entire car, or other methods of boundary layer
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Model
Deformation Measurement (MDM): MDM works by placing markers at known geometric locations on the wind tunnel model and taking photographs of the change in the marker's location as the wind in the tunnel is applied. By analyzing the change in marker positions from different camera viewing
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I remembered the wind tunnel in Göttingen was started as a tool for studies of Zeppelin behavior, but that it had proven to be valuable for everything else from determining the direction of smoke from a ship's stack, to whether a given airplane would fly. Progress at Aachen, I felt, would be
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There are many applications for boundary layer wind tunnel modeling. For example, understanding the impact of wind on high-rise buildings, factories, bridges, etc. can help building designers construct a structure that stands up to wind effects in the most efficient manner possible. Another
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Sublimation: If the air movement in the tunnel is sufficiently non-turbulent, a particle stream released into the airflow will not break up as the air moves along, but stay together as a sharp thin line. Multiple particle streams released from a grid of many nozzles can provide a dynamic
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and adding a diffuser between the test section and the fan located at the downstream end of the diffuser; this was an arrangement followed by a number of wind tunnels later built; in fact the open-return low-speed wind tunnel is often called the Eiffel-type wind tunnel.
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Evaporating suspensions are simply a mixture of some sort or fine powder, talc, or clay mixed into a liquid with a low latent heat of evaporation. When the wind is turned on the liquid quickly evaporates, leaving behind the clay in a pattern characteristic of the air
157:(CFD) modelling on high-speed digital computers has reduced the demand for wind tunnel testing, but has not completely eliminated it. Many real-world problems can still not be modeled accurately enough by CFD to eliminate the need for physical tests in wind tunnels.
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Wind tunnel tests are also performed to precisely measure the air movement of fans at a specific pressure. By determining the environmental circumstances during measurement, and by revising the air-tightness afterwards, the standardization of the data is ensured.
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Tufts, mini-tufts, or flow cones can be applied to a model and remain attached during testing. Tufts can be used to gauge air flow patterns and flow separation. Tufts are sometimes made of fluorescent material and are illuminated under black light to aid in
211:, a recent development in which multiple ultra-miniaturized pressure sensor modules are integrated into a flexible strip. The strip is attached to the aerodynamic surface with tape, and it sends signals depicting the pressure distribution along its surface.
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of 1949, which authorized expenditure to construct new wind tunnels at universities and at military sites. Some German war-time wind tunnels were dismantled for shipment to the United States as part of the plan to exploit German technology developments.
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However, the whirling arm does not produce a reliable flow of air impacting the test shape at a normal incidence. Centrifugal forces and the fact that the object is moving in its own wake mean that detailed examination of the airflow is difficult.
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flow is present, CFD is not practical due to limitations in present-day computing resources. For example, an area that is still much too complex for the use of CFD is determining the effects of flow on and around structures, bridges, and terrain.
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was designed without any use of wind tunnels. However, on one test, flight threads were attached to the surface of the wings, performing a wind tunnel type of test during an actual flight in order to refine the computational model. Where external
753:, the cross-section of a wind tunnel is typically circular rather than square, because there will be greater flow constriction in the corners of a square tunnel that can make the flow turbulent. A circular tunnel provides a smoother flow.
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less than 0.3, it is the primary parameter that governs the flow characteristics. There are three main ways to simulate high Reynolds number, since it is not practical to obtain full scale Reynolds number by use of a full scale vehicle.
1568:"For this purpose , the Society itself, through Mr. Wenham, had directed a machine to be constructed by Mr. Browning, who, he was sure, would take great interest in the work, and would give to it all the time and attention required."
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Because air is transparent it is difficult to directly observe the air movement itself. Instead, multiple methods of both quantitative and qualitative flow visualization methods have been developed for testing in a wind tunnel.
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through transparent portholes into the tunnel. Rather than simply being flat discs, these lighting and observation windows may be curved to match the cross-section of the tunnel and further reduce turbulence around the window.
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The force balance itself creates drag and potential turbulence that will affect the model and introduce errors into the measurements. The supporting structures are therefore typically smoothly shaped to minimize turbulence.
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On 22 June 1942, Curtiss-Wright financed construction of one of the nation's largest subsonic wind tunnels in Buffalo, NY. The first concrete for building was poured on 22 June 1942 on a site that eventually would become
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is typically used for underwater aquadynamic testing. The interaction between two different types of fluids means that pure wind tunnel testing is only partly relevant. However, a similar sort of research is done in a
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three-dimensional shape of the airflow around a body. As with the force balance, these injection pipes and nozzles need to be shaped in a manner that minimizes the introduction of turbulent airflow into the airstream.
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air out of the test section downstream, the fan-blade turbulence is not a factor), and so is not directly useful for accurate measurements. The air moving through the tunnel needs to be relatively turbulence-free and
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angles, the translational change in location of the marker can be calculated. By collecting results from a few markers, the degree to which the model is flexibly yielding due to the air load can be calculated.
281:(1773–1857) also used a whirling arm to measure the drag and lift of various airfoils. His whirling arm was 5 feet (1.5 m) long and attained top speeds between 10 and 20 feet per second (3 to 6 m/s).
137:. Initially, automakers would test out scale models of their cars, but later, full scale automotive wind tunnels were built. Starting in the 1960s, wind tunnel testing began to receive widespread adoption for
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are machines in which objects are held stationary inside a tube, and air is blown around it to study the interaction between the object and the moving air. They are used to test the aerodynamic effects of
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tunnels require large cross section area, but only small velocities. Since power varies with the cube of velocity, the power required for the operation is also less. An example of a V/STOL tunnel is the
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Climatic tunnels are used to evaluate the performance of door systems, braking systems, etc. under various climatic conditions. Most of the leading automobile manufacturers have their own climatic wind
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Pressure across the surfaces of the model can be measured if the model includes pressure taps. This can be useful for pressure-dominated phenomena, but this only accounts for normal forces on the body.
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on a hydraulic installation. Two measuring tubes enable measurements of lower air currents (< 30,000 m/h) as well as higher air currents (< 60,000 m/h). The determination of the Q/h curve of the
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volumes of air which could then be routed through the wind tunnels. By the end of the war, Germany had at least three different supersonic wind tunnels, with one capable of Mach 4.4 (heated) airflows.
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and Arthur L. Klein. He objected to their design and insisted on a return flow making the device "independent of the fluctuations of the outside atmosphere". It was completed in 1930 and used for
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was in some ways revolutionary. It can be seen from the above, however, that they were simply using the accepted technology of the day, though this was not yet a common technology in America.
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demonstrated that the airflow pattern over a scale model would be the same for the full-scale vehicle if a certain flow parameter were the same in both cases. This factor, now known as the
207:, in which higher local pressure is indicated by lowered fluorescence of the paint at that point. Pressure distributions can also be conveniently measured by the use of pressure-sensitive
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designed to provide supersonic flow. The observation or instrumentation chamber ("test section") was then placed at the proper location in the throat or nozzle for the desired airspeed.
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Later research into airflows near or above the speed of sound used a related approach. Metal pressure chambers were used to store high-pressure air which was then accelerated through a
959:. A different class of wind tunnels are oriented vertically so that gravity can be balanced by drag instead of lift, and these have become a popular form of recreation for simulating
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off of the model. This technique is primarily employed to verify that trip dots placed at the leading edge in order to force a transition are successfully achieving the intended goal.
98:. Different wind tunnels range in size from less than a foot across, to over 100 feet (30 m), and can have air that moves at speeds from a light breeze to hypersonic velocities.
597:, left, is joined by Air Force and NASA officials while inspecting two of the models used in the high velocity, high altitude wind tunnels at Arnold Air Force Base. The missiles are
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and prospect of more advanced research, he wrote, "I was in favor of constructing such a plane because I have never believed that you can get all the answers out of a wind tunnel."
399:(1832–1923) built his first open-return wind tunnel in 1909, powered by a 67 hp (50 kW) electric motor, at Champs-de-Mars, near the foot of the tower that bears his name.
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would be held still and the air moved around it. In this way, a stationary observer could study the flying object in action, and could measure the aerodynamic forces acting on it.
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Subsequent use of wind tunnels proliferated as the science of aerodynamics and discipline of aeronautical engineering were established and air travel and power were developed.
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The aerodynamic principles of the wind tunnel work equally on watercraft, except the water is more viscous and so sets greater forces on the object being tested. A looping
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where the wind stream is upwards for the testing of models in spin situations and the concepts and engineering designs for the first primitive helicopters flown in the US.
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Wind tunnels are also classified by the orientation of air flow in the test section with respect to gravity. Typically they are oriented horizontally, as happens during
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asked what was required to advance the USAF, and von Kármán answered, "The first step is to build the right wind tunnel." On the other hand, after the successes of the
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746:. To correct this problem, closely spaced vertical and horizontal air vanes are used to smooth out the turbulent airflow before reaching the subject of the testing.
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is one of the main objectives. To determine this curve (and to define other parameters) air technical, mechanical as well as electro technical data are measured:
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446:, France. It was designed to test full-size aircraft and had six large fans driven by high powered electric motors. The Chalais-Meudon wind tunnel was used by
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Between 1909 and 1912 Eiffel ran about 4,000 tests in his wind tunnel, and his systematic experimentation set new standards for aeronautical research. In 1912
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strain on the driver, and flow separation on the back side of the helmet can cause turbulent buffeting and thus blurred vision for the driver at high speeds.
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Various techniques are used to study the actual airflow around the geometry and compare it with theoretical results, which must also take into account the
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The pressure distributions across the test model have historically been measured by drilling many small holes along the airflow path, and using multi-tube
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There are many different kinds of wind tunnels. They are typically classified by the range of speeds that are achieved in the test section, as follows:
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High-speed cameras are also required when the subject of the test is itself moving at high speed, such as an airplane propeller. The camera can capture
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is used to obtain multiple readings downstream of the test model, or a multiple-tube manometer is mounted downstream and all its readings are taken.
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During WWII, Germany developed different designs of large wind tunnels to further their knowledge of aeronautics. For example, the wind tunnel at
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1464:"An account of the experiments, relating to the resistance of the air, exhibited at different times before the Royal Society, in the year 1746"
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Oil: When oil is applied to the model surface it can clearly show the transition from laminar to turbulent flow as well as flow separation.
1592:"An Historical and Applied Aerodynamic Study of the Wright Brothers' Wind Tunnel Test Program and Application to Successful Manned Flight"
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images of how the blade cuts through the particulate streams and how vortices are generated along the trailing edges of the moving blade.
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buffer zone between the object and the tunnel walls. There are correction factors to relate wind tunnel test results to open-air results.
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bubbles of liquid can be introduced into the airflow upstream of the test model, and their path around the model can be photographed (see
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A high enthalpy wind tunnel is intended to study flow of air around objects moving at speeds much faster than the local speed of sound (
548:. With its 26 ft (8 m) test section and airspeed up to Mach 1, it is the largest transonic wind tunnel facility in the world.
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The airflow created by the fans that is entering the tunnel is itself highly turbulent due to the fan blade motion (when the fan is
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testing can produce reliable information for designers, especially when their projects are in complex terrain or on exposed sites.
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In the United States, concern over the lagging of American research facilities compared to those built by the Germans led to the
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The most effective way to simulative external turbulent flow is through the use of a boundary layer wind tunnel.
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384:' use of a simple wind tunnel in 1901 to study the effects of airflow over various shapes while developing their
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building's internal structure or else the building will collapse. Determining such forces was required before
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to measure the pressure at each hole. Pressure distributions can more conveniently be measured by the use of
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and film cameras or high-speed digital cameras can help to capture events that are a blur to the naked eye.
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Until World War II, the world's largest wind tunnel, built in 1932–1934, was located in a suburb of Paris,
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F.L. Wattendorf (May 1946) "Reports on selected topics of German and Swiss aeronautical developments", in
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Due to the sheer volume and speed of air movement required, the fans may be powered by stationary
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design. For instance, the use of boundary layer wind tunnel modeling can be used as a credit for
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642:(CFD) can supplement or possibly replace the use of wind tunnels. For example, the experimental
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Wind tunnel testing was first applied to automobiles as early as the 1920s, on cars such as the
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is one of the governing similarity parameters for the simulation of flow in a wind tunnel. For
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and suggested the construction of a wind tunnel for tests of airships they were designing. The
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wind tunnel test on a human subject, showing the effects of high wind speeds on the human face
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In certain particular test cases, other similarity parameters must be satisfied, such as e.g.
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depends on the purpose of the test, but the most important conditions to satisfy are usually:
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1483:"Sir George Cayley: The Invention of the Aeroplane near Scarborough at the Time of Trafalgar"
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Air is blown or sucked through a duct equipped with a viewing port and instrumentation where
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1640:"Man-Made Hurricane Tests Full-Sized Planes; Giant Battery of Fans Helps Makes Flying Safe"
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That Wenham and Browning were attempting to build a wind tunnel is briefly mentioned in:
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The measurement can take place on the fan or in the application in which the fan is used.
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in a wind tunnel and around the actual object is not equal to having identical airspeeds).
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of turbulence downstream of a cylinder was tested in the tunnel. When he later moved to
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built an open-section wind tunnel with a centrifugal blower in 1897, and determined the
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These tunnels are used in the studies of noise generated by flow and its suppression.
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apparatus to determine drag and did some of the first experiments in aviation theory.
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1922:. Forschungsinstitut für Kraftfahrwesen und Fahrzeugmotoren Stuttgart. Archived from
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Cryogenic tunnels: Here test gas is cooled down to increase the Reynolds number. The
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Pressurised tunnels: Here test gases are pressurised to increase the Reynolds number.
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Seventh Annual Report of the Aeronautical Society of Great Britain for the Year 1872
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Sixth Annual Report of the Aeronautical Society of Great Britain for the Year 1871
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applied wind tunnels in his process of developing and refining the technology of
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Geometric similarity: all dimensions of the object must be proportionally scaled.
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2096:. Thanks to updated measurement techniques, wind tunnels remain indispensable.
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In 1872, the wind tunnel was demonstrated to the Aeronautical Society. See:
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Pressure distributions on a test model can also be determined by performing a
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1069:
External flow tunnels are used to study the external flow through the chassis
867:
750:
693:
662:
Preparing a model in the Kirsten Wind Tunnel, a subsonic wind tunnel at the
651:
544:, France in 1946 where it was re-erected and is still operated there by the
306:
200:
536:, Austria would have had two fans directly driven by two 50,000 horsepower
17:
743:
1207:
1163:
1147:
1117:
882:
High-speed turbulence and vortices can be difficult to see directly, but
727:
509:
455:
165:
Air velocity and pressures are measured in several ways in wind tunnels.
95:
83:
458:
airplanes. Today, this wind tunnel is preserved as a national monument.
789:
557:
533:
490:
1737:
1609:
521:
models could be tested at air speeds of 400 mph (640 km/h).
1409:
Lissaman, P. B. S. (1 January 1983). "Low-Reynolds-Number Airfoils".
1037:
1010:
541:
392:
354:
287:
used a rotating arm to accurately measure wing airfoils with varying
87:
64:
1284:
1396:, Aerospace Engineering & Manufacturing, March 2009, pp. 27-28
1300:
1285:"The Time Tunnel - An Historical Survey of Automotive Aerodynamics"
1162:
There are two possible ways of measurement: a complete fan, or an
1129:
1100:
1094:
1006:
788:
712:
683:
657:
615:
589:
571:
545:
447:
414:
305:
58:
46:
40:
31:
27:
Machine used for studying the effects of air moving around objects
1866:"China gears up to test weapons that could hit US in 14 minutes"
1042:
1014:
450:
under the name S1Ch until 1976 in the development of, e.g., the
36:
1146:
actual size, in order to slow down the wing beats and make the
192:
Aerodynamic forces on the test model are usually measured with
1842:
Vectored Propulsion, Supermaneuverability & Robot Aircraft
681:(LEED) certification through the U.S. Green Building Council.
196:, connected to the test model with beams, strings, or cables.
91:
1704:
Aeronautical Research in Germany: From Lilienthal Until Today
982:
The main subcategories in the aeronautical wind tunnels are:
1150:
generated by the insect wings easier to see and understand.
430:
In 1931 the NACA built a 30 by 60 feet (9.1 by 18.3 m)
1648:. 19 January 1936. pp. 94–95 – via Google Books.
1255:, the first suspension bridge to be tested in a wind tunnel
1080:
built the first full-scale wind tunnel for motor vehicles.
717:
Six-element external balance below the Kirsten Wind Tunnel
122:
could specify the required strength of such buildings and
1013:
are used as test gases. The transonic dynamics tunnel at
2090:"Wind Tunnels Have Future in Digital Age, Europeans Say"
1084:
control such as scoops or perforations to suck it away.
168:
Air velocity through the test section is determined by
860:
Fog (usually from water particles) is created with an
857:
create a luminous flow pattern with the tempera paint.
1827:
Goldstein, E., "Wind Tunnels, Don't Count Them Out,"
1261:, the hydrodynamics-oriented version of a wind tunnel
1045:
Langley 14 by 22 ft (4.3 by 6.7 m) tunnel.
1702:
Ernst Heinrich Hirschel, Horst Prem, Gero Madelung,
1468:
Mathematical Tracts of the late Benjamin Robins, Esq
126:
continue to be used for large or unusual buildings.
1057:. These tunnels are used to study that phenomenon.
813:. This allows one to produce common curves such as
2066:Jewel B. Barlow, William H. Rae, Jr., Allan Pope:
1065:Automotive wind tunnels fall into two categories:
696:wind tunnel in 1990, before it was retired in 2004
1516:"Bjorn's Corner: Aircraft drag reduction, Part 2"
1885:"Windless Wind Tunnels for High Altitude Tests."
552:reported on this wind tunnel for a US response.
485:virtually impossible without a good wind tunnel.
361:In a classic set of experiments, the Englishman
1738:"Calspan History > Wind Tunnel Construction"
295:polar diagrams, but was lacking the notions of
114:War for development of aircraft and missiles.
1971:Review of Aeronautical Wind Tunnel Facilities
1766:, Hearst Magazines, July 1946, pp. 66–72
679:Leadership in Energy and Environmental Design
8:
1103:, Moscow, built in 1941 for aircraft testing
532:A large wind tunnel under construction near
267:English military engineer and mathematician
1053:Aircraft have a tendency to spin when they
310:Replica of the Wright brothers' wind tunnel
435:closed and, even though it was declared a
2041:
1430:
377:is based upon the Reynolds number alone.
2015:"A century of wind tunnels since Eiffel"
560:, where the wind tunnel still operates.
39:wind tunnel with the scale model of the
1537:(first ed.). Osprey. p. 281.
1275:
1017:Langley is an example of such a tunnel.
737:air into the test section – when it is
337:of flat plates, cylinders and spheres.
1667:
1665:
1663:
1661:
1659:
1657:
1655:
1503:from the original on 26 December 2013.
1348:10.1146/annurev.fluid.38.050304.092016
1005:Heavy gas tunnels: Heavier gases like
489:When von Kármán began to consult with
352:used a wind tunnel when designing his
1186:Specific efficiency (W/1000 m/h)
730:engines rather than electric motors.
321:Aeronautical Society of Great Britain
319:(1824–1908), a Council Member of the
7:
2094:Aviation Week & Space Technology
2053:from the original on 9 October 2022.
1760:"Wind at Work For Tomorrow's Planes"
1596:Defence Technical Information Center
1831:, Vol. 48 #4, April 2010, pp. 38–43
1441:10.1146/annurev.fl.15.010183.001255
1383:from the original on 20 April 2018.
1028:at 80 to 200 miles above the earth.
439:in 1995, demolition began in 2010.
67:with helium-filled bubbles showing
1973:National Academies, 1988 pp. 34–37
1610:"Laboratoire Aerodynamique Eiffel"
1101:Central Aerohydrodynamic Institute
937:Subsonic and transonic wind tunnel
480:he recalled use of this facility:
51:16-foot supersonic wind tunnel at
25:
1888:, Hearst Magazines, February 1952
1784:, Hearst Magazines, February 1945
1470:. Vol. 1. London: J. Nourse.
1141:Low-speed oversize liquid testing
161:Measurement of aerodynamic forces
1990:. Carlzimmer.com. Archived from
1625:US Navy Experimental Wind Tunnel
1411:Annual Review of Fluid Mechanics
1328:Annual Review of Fluid Mechanics
817:versus angle of attack (shown).
419:German aviation laboratory, 1935
1514:Bjorn Fehrm (27 October 2017).
1490:Journal of Aeronautical History
1398:Society of Automotive Engineers
1177:Static pressure difference (Pa)
2088:Thierry Dubois (11 May 2017).
2068:Low speed wind tunnels testing
2013:Chanetz, Bruno (August 2017).
1099:Vertical wind tunnel T-105 at
1022:European transonic wind tunnel
1:
1946:"Ground proximity simulation"
1692:, Hearst Magazines, July 1941
785:Force and moment measurements
772:for the regime of operation.
271:(1707–1751) invented a
1901:14'x22' Subsonic Wind Tunnel
1374:Airflow Sciences Corporation
1253:Tacoma Narrows Bridge (1950)
986:High Reynolds number tunnels
805:With the model mounted on a
640:computational fluid dynamics
632:Unitary Wind Tunnel Plan Act
623:with a wind tunnel model at
155:computational fluid dynamics
1727:, link from Governmentattic
1324:"Aerodynamics of Race Cars"
1283:Ludvigsen, Karl E. (1970).
218:, in which either a single
2145:
2129:19th-century introductions
2043:10.1016/j.crme.2017.05.012
1795:Hiebert, David M. (2002).
1462:James Wilson, ed. (1761).
1289:SAE Technical Paper Series
1238:Index of aviation articles
1212:Rotations per minute (RPM)
907:Particle Image Velocimetry
638:For limited applications,
437:National Historic Landmark
187:particle image velocimetry
1986:Popular Science, Dec 2002
1844:, Springer Verlag, 1990,
1481:J. A. D. Ackroyd (2011).
1206:Admitted power (W) fan /
1180:Amount of moved air (m/h)
978:Aeronautical wind tunnels
951:High enthalpy wind tunnel
2022:Comptes Rendus Mécanique
1870:South China Morning Post
1689:400mph Wind Tests Planes
1535:A Dictionary of Aviation
1533:Wragg, David W. (1973).
1220:Wind engineering testing
842:Carbon dioxide injection
664:University of Washington
367:University of Manchester
205:pressure-sensitive paint
1183:Average air speed (m/s)
690:Langley Research Center
625:Langley Research Center
358:from 1897 and onwards.
1778:"Vertical Wind Tunnel"
1367:"Racing Helmet Design"
1104:
974:also being important.
947:Hypersonic wind tunnel
942:Supersonic wind tunnel
932:High speed wind tunnel
802:
749:Due to the effects of
718:
697:
666:
627:
606:
587:
487:
432:full-scale wind tunnel
420:
331:Konstantin Tsiolkovsky
317:Francis Herbert Wenham
311:
172:. Measurement of the
75:
56:
44:
1920:"History (1930–1945)"
1098:
927:Low-speed wind tunnel
792:
776:Pressure measurements
716:
687:
661:
619:
593:
582:
482:
418:
309:
291:, establishing their
170:Bernoulli's principle
62:
53:Arnold Air Force Base
50:
35:
1365:James C. Paul, P.E.
1322:Joseph Katz (2006).
1265:List of wind tunnels
1088:Aeroacoustic tunnels
1024:uses this technique.
968:Vertical wind tunnel
897:Quantitative methods
470:Göttingen University
348:in the early 1890s.
131:Rumpler Tropfenwagen
2034:2017CRMec.345..581C
1969:Ronald Smelt (ed),
1872:. 15 November 2017.
1725:Toward New Horizons
1676:The Wind and Beyond
1672:Theodore von Kármán
1423:1983AnRFM..15..223L
1394:Going with the flow
1340:2006AnRFM..38...27K
1193:Electro technical:
834:Qualitative methods
595:Theodore von Kármán
466:Theodore von Kármán
404:Eiffel's laboratory
365:(1842–1912) of the
350:Carl Rickard Nyberg
1590:Dodson MG (2005).
1105:
1061:Automotive tunnels
825:Flow visualization
803:
719:
698:
667:
628:
607:
588:
568:After World War II
538:hydraulic turbines
421:
375:dynamic similarity
312:
293:lift-to-drag ratio
76:
57:
45:
43:wide-body airliner
2076:978-0-471-55774-6
1840:Benjamin Gal-Or,
1829:Aerospace America
1645:Popular Mechanics
1243:Automobile design
1124:Aquadynamic flume
580:
478:Aachen University
335:drag coefficients
279:Sir George Cayley
182:compressible flow
16:(Redirected from
2136:
2103:Rail Tec Arsenal
2097:
2055:
2054:
2052:
2045:
2019:
2010:
2004:
2003:
2001:
1999:
1980:
1974:
1967:
1961:
1960:
1958:
1956:
1942:
1936:
1935:
1933:
1931:
1916:
1910:
1909:
1908:on 21 March 2009
1904:, archived from
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1890:
1889:
1880:
1874:
1873:
1862:
1856:
1838:
1832:
1825:
1819:
1818:
1816:
1814:
1808:
1802:. Archived from
1801:
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1774:
1768:
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1434:
1406:
1400:
1391:
1385:
1384:
1382:
1371:
1362:
1356:
1355:
1350:. Archived from
1319:
1313:
1312:
1280:
1226:wind engineering
815:lift coefficient
795:lift coefficient
581:
550:Frank Wattendorf
411:Widespread usage
363:Osborne Reynolds
340:Danish inventor
301:Reynolds numbers
289:angles of attack
174:dynamic pressure
153:The advances in
135:Chrysler Airflow
133:, and later the
73:wingtip vortices
21:
2144:
2143:
2139:
2138:
2137:
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2133:
2109:
2108:
2087:
2084:
2063:
2061:Further reading
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2017:
2012:
2011:
2007:
1997:
1995:
1982:
1981:
1977:
1968:
1964:
1954:
1952:
1944:
1943:
1939:
1929:
1927:
1926:on 19 July 2011
1918:
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1893:
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1877:
1864:
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1859:
1839:
1835:
1826:
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1812:
1810:
1809:on 9 March 2013
1806:
1799:
1794:
1793:
1789:
1782:Popular Science
1776:
1775:
1771:
1764:Popular Science
1758:
1757:
1753:
1743:
1741:
1736:
1735:
1731:
1722:
1718:
1706:Springer, 2004
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1500:
1485:
1480:
1479:
1475:
1461:
1460:
1456:
1432:10.1.1.506.1131
1408:
1407:
1403:
1392:
1388:
1380:
1369:
1364:
1363:
1359:
1354:on 18 May 2021.
1321:
1320:
1316:
1282:
1281:
1277:
1273:
1248:Sting (fixture)
1234:
1222:
1173:Air technical:
1156:
1143:
1126:
1110:
1090:
1063:
1051:
1035:
991:Reynolds number
988:
980:
920:
899:
836:
827:
811:angle of attack
799:angle of attack
787:
778:
766:Reynolds number
711:
572:
570:
518:
493:he worked with
413:
382:Wright brothers
371:Reynolds number
285:Otto Lilienthal
269:Benjamin Robins
265:
260:
244:Reynolds number
178:static pressure
163:
143:fuel efficiency
101:Usually, large
28:
23:
22:
15:
12:
11:
5:
2142:
2140:
2132:
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2083:
2082:External links
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2005:
1994:on 8 July 2011
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1937:
1911:
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1417:(1): 223–239.
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1301:10.4271/700035
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1033:V/STOL tunnels
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918:Classification
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846:visualization.
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688:Fan blades of
675:green building
603:Atlas Series-B
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566:
517:
514:
506:General Arnold
499:Northrop Alpha
495:Clark Millikan
468:'s teacher at
462:Ludwig Prandtl
444:Chalais-Meudon
412:
409:
397:Gustave Eiffel
264:
261:
259:
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209:pressure belts
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120:building codes
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2028:(8): 581–94.
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1854:3-540-97161-0
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1850:0-387-97161-0
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1740:. calspan.com
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1108:High enthalpy
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1078:Wunibald Kamm
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2124:Wind tunnels
2119:Aerodynamics
2093:
2067:
2025:
2021:
2008:
1996:. Retrieved
1992:the original
1985:
1978:
1970:
1965:
1953:. Retrieved
1950:www.dnw.aero
1949:
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1928:. Retrieved
1924:the original
1914:
1906:the original
1900:
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1804:the original
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1352:the original
1334:(1): 27–63.
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1259:Water tunnel
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1111:
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989:
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957:level flight
954:
921:
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828:
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709:How it works
703:
699:
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647:SpaceShipOne
644:rocket plane
637:
629:
621:Mary Jackson
608:
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531:
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516:World War II
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390:
386:Wright Flyer
379:
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342:Poul la Cour
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325:aspect ratio
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297:induced drag
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79:Wind tunnels
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29:
1930:3 September
1200:Current (A)
1197:Tension (V)
1154:Fan testing
1135:towing tank
995:mach number
891:stop-motion
770:Mach number
692:'s 16-foot
238:Mach number
234:Mach number
216:wake survey
180:, and (for
139:automobiles
124:these tests
18:Wind-tunnel
2113:Categories
2070:(3rd ed.)
1955:1 December
1712:354040645X
1566:From p. 6:
1496:: 130–81.
1271:References
1189:Efficiency
1116:speeds). "
1114:hypersonic
961:sky-diving
862:ultrasonic
793:A typical
526:Peenemünde
220:pitot tube
201:manometers
1577:pp. 6–12.
1449:123639541
1427:CiteSeerX
1309:0148-7191
868:nebulizer
751:viscosity
694:transonic
652:turbulent
501:testing.
452:Caravelle
96:buildings
69:pathlines
2048:Archived
1744:23 April
1564:, p. 6.
1498:Archived
1378:Archived
1232:See also
1208:impeller
1164:impeller
1148:vortices
1118:Enthalpy
728:turbofan
605:. (1959)
510:Bell X-2
504:In 1939
456:Concorde
427:blades.
84:aircraft
63:A model
2030:Bibcode
1998:28 June
1813:3 April
1714:, p. 87
1674:(1967)
1419:Bibcode
1336:Bibcode
1073:tunnels
797:versus
744:laminar
739:sucking
735:blowing
599:AGARD-B
558:Calspan
534:Oetztal
491:Caltech
263:Origins
258:History
88:rockets
71:of the
2074:
1848:
1710:
1628:, 1915
1557:Note:
1541:
1520:Leeham
1447:
1429:
1307:
1038:V/STOL
1011:R-134a
723:models
611:nozzle
542:Modane
393:France
355:Flugan
176:, the
94:, and
65:Cessna
55:, 1960
2051:(PDF)
2018:(PDF)
1807:(PDF)
1800:(PDF)
1501:(PDF)
1486:(PDF)
1445:S2CID
1381:(PDF)
1370:(PDF)
1203:Cos φ
1130:flume
1055:stall
1007:freon
850:flow.
839:Smoke
801:curve
546:ONERA
448:ONERA
41:MD-11
2072:ISBN
2000:2011
1957:2022
1932:2010
1846:ISBN
1815:2014
1746:2015
1708:ISBN
1539:ISBN
1305:ISSN
1043:NASA
1015:NASA
1009:and
768:and
601:and
584:NACA
464:was
454:and
380:The
299:and
103:fans
92:cars
37:NASA
2038:doi
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1168:fan
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