Статті в журналах: "Wind tunnel cascade test"

1

Kiock, R., F. Lehthaus, N. C. Baines, and C. H. Sieverding. "The Transonic Flow Through a Plane Turbine Cascade as Measured in Four European Wind Tunnels." Journal of Engineering for Gas Turbines and Power 108, no. 2 (April 1, 1986): 277–84. http://dx.doi.org/10.1115/1.3239900.

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Reliable cascade data are esssential to the development of high-speed turbomachinery, but it has long been suspected that the tunnel environment influences the test results. This has now been investigated by testing one plane gas turbine rotor blade section in four European wind tunnels of different test sections and instrumentation. The Reynolds number of the transonic flow tests was Re2 = 8 × 105 based on exit flow conditions. The turbulence was not increased artificially. A comparison of results from blade pressure distributions and wake traverse measurements reveals the order of magnitude of tunnel effects.

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2

Rona, Aldo, Renato Paciorri, and Marco Geron. "Design and Testing of a Transonic Linear Cascade Tunnel With Optimized Slotted Walls." Journal of Turbomachinery 128, no. 1 (June 23, 2005): 23–34. http://dx.doi.org/10.1115/1.2101856.

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In linear cascade wind tunnel tests, a high level of pitchwise periodicity is desirable to reproduce the azimuthal periodicity in the stage of an axial compressor or turbine. Transonic tests in a cascade wind tunnel with open jet boundaries have been shown to suffer from spurious waves, reflected at the jet boundary, that compromise the flow periodicity in pitch. This problem can be tackled by placing at this boundary a slotted tailboard with a specific wall void ratio s and pitch angle α. The optimal value of the s-α pair depends on the test section geometry and on the tunnel running conditions. An inviscid two-dimensional numerical method has been developed to predict transonic linear cascade flows, with and without a tailboard, and quantify the nonperiodicity in the discharge. This method includes a new computational boundary condition to model the effects of the tailboard slots on the cascade interior flow. This method has been applied to a six-blade turbine nozzle cascade, transonically tested at the University of Leicester. The numerical results identified a specific slotted tailboard geometry, able to minimize the spurious reflected waves and regain some pitchwise flow periodicity. The wind tunnel open jet test section was redesigned accordingly. Pressure measurements at the cascade outlet and synchronous spark schlieren visualization of the test section, with and without the optimized slotted tailboard, have confirmed the gain in pitchwise periodicity predicted by the numerical model.

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3

Zhang, Jian Guo, and Hui Min Zhuang. "Wind Tunnel Test of Tall Buildings with Irregularities of Elevation." Applied Mechanics and Materials 578-579 (July 2014): 1208–11. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.1208.

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In this paper, 2 high-rise building models with ladder and cascade irregularities of elevation were tested in a wind tunnel respectively to measure the mean and fluctuating wind pressure distributions. The mean and RMS (root-mean-square) coefficients of the drag, lift and torsion moment on the measuring layer were obtained from the wind pressures. In the direction which the buildings were positive in the wind, the variation of these above mentioned coefficients with height and the power spectrum densities of the fluctuating wind loads on sudden changed positions were analyzed in detail. Compared with the elevation regular tall building, the wind load characteristics of irregular ones were more complicated.

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4

Borovkov, Aleksei. "Efficiency Analysis of Blade Cascades of Axial Compressors by the Results of Wind Tunnel Test." Journal of Advanced Research in Dynamical and Control Systems 12, no. 01-Special Issue (February 13, 2020): 953–61. http://dx.doi.org/10.5373/jardcs/v12sp1/20201146.

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5

Fořt, J., J. Fürst, J. Halama, V. Hric, P. Louda, M. Luxa, and D. Šimurda. "Numerical simulation of flow through cascade in wind tunnel test section and stand-alone configurations." Applied Mathematics and Computation 319 (February 2018): 633–46. http://dx.doi.org/10.1016/j.amc.2017.07.040.

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6

Hake, Leander, Felix Reinker, Robert Wagner, Stefan aus der Wiesche, and Markus Schatz. "The Profile Loss of Additive Manufactured Blades for Organic Rankine Cycle Turbines." International Journal of Turbomachinery, Propulsion and Power 7, no. 1 (March 21, 2022): 11. http://dx.doi.org/10.3390/ijtpp7010011.

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Results from an experimental profile loss study are presented of an additive manufactured linear turbine cascade placed in the test section of a closed-loop organic vapor wind tunnel. This test facility at Muenster University of Applied Sciences allows the investigation of high subsonic and transonic organic vapor flows under ORC turbine flow conditions at elevated pressure and temperature levels. An airfoil from the open literature was chosen for the cascade, and the organic vapor was Novec 649TM. Pitot probes measured the flow field upstream and downstream of the cascade. The inflow turbulence level was 0.5%. The roughness parameters of the metal-printed blades were determined, and the first set of flow measurements was performed. Then, the blade surfaces were further finished, and the impact of roughness on profile losses was assessed in the second flow measurement set. Although the Reynolds number level was relatively high, further surface treatment reduces the profile loss noticeably in organic vapor flows through the printed cascade.

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7

Niehuis, Reinhard, and Martin Bitter. "The High-Speed Cascade Wind Tunnel at the Bundeswehr University Munich after a Major Revision and Upgrade." International Journal of Turbomachinery, Propulsion and Power 6, no. 4 (October 29, 2021): 41. http://dx.doi.org/10.3390/ijtpp6040041.

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Since its first operation in 1956 at DFL Braunschweig and after its movement to Munich, the High-Speed Cascade Wind Tunnel (HGK) at Bundeswehr University Munich is intensively used for fundamental and application-oriented research on aero-thermodynamics of turbomachinery bladings. Numerous systematic airfoil design studies were performed over the last decades. Thanks to the HGK facility, which enables thorough and detailed cascade testing at turbomachinery-relevant conditions, many of those airfoils for different purposes finally made it into turbomachinery applications. Nowadays, the HGK still provides very useful contributions to the understanding of the complicated flow in compressor and turbine bladings, and thereby extends the knowledge on relevant physical phenomena. As a consequence of the intense usage, this unique test facility was subject to a major revision and upgrade. The performed changes are presented within this paper including an overview on new capabilities in terms of the extended operating range, the data acquisition system, and the recently available measurement equipment.

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8

Rechter, H., W. Steinert, and K. Lehmann. "Comparison of Controlled Diffusion Airfoils With Conventional NACA 65 Airfoils Developed for Stator Blade Application in a Multistage Axial Compressor." Journal of Engineering for Gas Turbines and Power 107, no. 2 (April 1, 1985): 494–98. http://dx.doi.org/10.1115/1.3239758.

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In their transonic cascade wind tunnel, DFVLR has done measurements on a conventional NACA 65, as well as on a controlled diffusion airfoil, designed for the same velocity triangle at supercritical inlet condition. These tested cascades represent the first stator hub section of a three-stage axial/one-stage radial combined compressor developed by MTU with the financial aid of the German Ministry of Research and Technology. One aspect of this project was the verification of the controlled diffusion concept for axial compressor blade design, in order to demonstrate the capabilities of some recent research results which are now available for industrial application. The stator blades of the axial compressor section were first designed using NACA 65 airfoils. In the second step, the controlled diffusion technique was applied for building a new stator set. Both stator configurations were tested in the MTU compressor test facility. Cascade and compressor tests revealed the superiority of the controlled diffusion airfoils for axial compressors. In comparison to the conventional NACA blades, the new blades obtained a higher efficiency. Furthermore, a closer matching of the compressor performance data to the design requirements was possible due to a more precise prediction of the turning angle.

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9

Tweedt, D. L., H. A. Schreiber, and H. Starken. "Experimental Investigation of the Performance of a Supersonic Compressor Cascade." Journal of Turbomachinery 110, no. 4 (October 1, 1988): 456–66. http://dx.doi.org/10.1115/1.3262219.

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Results are presented from an experimental investigation of a linear, supersonic compressor cascade tested in the supersonic cascade wind tunnel facility at the DFVLR in Cologne, Federal Republic of Germany. The cascade was derived from the near-tip section of a high-throughflow axial flow compressor rotor and has a design relative inlet Mach number of 1.61. Test data were obtained over the range of inlet Mach numbers from 1.30 to 1.17. Side-wall boundary layer suction was used to reduce secondary flow effects within the blade passages and to control the axial-velocity-density ratio (AVDR). Flow velocity measurements showing the wave pattern in the entrance region were obtained with a laser anemometer. The unique-incidence relationship for this cascade, relating the supersonic inlet Mach number to the inlet flow direction, is discussed. The influence of static pressure ratio and AVDR on the blade performance is described, and an empirical correlation is used to show the influence of these (independent) parameters for fixed inlet conditions on the exit flow direction and the total-pressure losses.

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10

Vlček, Václav, and Pavel Procházka. "Test section of the wind tunnel IT for aeroelastic experiments with blade cascades." EPJ Web of Conferences 213 (2019): 02095. http://dx.doi.org/10.1051/epjconf/201921302095.

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The article presents the way how the existing small vacuum aerodynamic tunnel IT (Institute of Thermomechanics) has been adapted for the measurement of the aeroelastic properties of the NACA 0015 airfoil and of the blade cascades composed of various types of blades with two degrees of freedom, pitch and common plunge. Attention was focused on the possibility of studying self-excited vibration at lower subsonic speeds. The modification of the test section is based on the knowledge gained during the study of self-excited airfoil oscillation.

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11

Šidlof, Petr, David Šimurda, Jan Lepicovsky, and Martin Štěpán. "Aerodynamic and dynamic loading in a blade cascade designed for flutter research." EPJ Web of Conferences 264 (2022): 01041. http://dx.doi.org/10.1051/epjconf/202226401041.

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Flow-induced vibration of turbine and compressor blades, so called blade flutter, represents a serious problem for designers and operators of large turbomachines. The research of mechanisms leading to this dangerous aeroelastic instability, which can occur especially in modern long and slender blades, is hindered by lack of experimental data. A new experimental setup for controlled flutter testing has been designed in cooperation of the Institute of Thermomechanics of the Czech Academy of Sciences and Faculty of Mechatronics of the Technical University of Liberec. The test section consists of five planar blades placed in a transonic wind tunnel, with high-frequency torsional oscillation of the middle blade driven by an electric motor. The contribution presents the results of first measurements, namely the static pressure distribution for various inlet Mach numbers, aerodynamic moments and deformation of the middle blade due to inertial loads during high-frequency oscillation.

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12

Slama, Vaclav, Bartolomej Rudas, Jiri Ira, Ales Macalka, Petr Eret, and Volodymyr Tsymbalyuk. "CFD prediction of flutter of turbine blades and comparison with an experimental test case." MATEC Web of Conferences 168 (2018): 02005. http://dx.doi.org/10.1051/matecconf/201816802005.

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Last stage blades are a key element of steam turbines and in many ways determine the turbine configuration alongside with the overall turbine performance. The total efficiency of the low pressure turbine section can be increased by extending the last stage blades. The design process of such long blades involves a flutter analysis using CFD tools which have to be validated by measurements in test facilities under various operating conditions. Experimental data obtained from a subsonic wind tunnel with an oscillating turbine blade cascade, which is available at the Department of Power System Engineering at the University of West Bohemia, was compared with simulations in ANSYS CFX currently used in the Doosan Škoda Power. The paper provides a brief summary of experimental rig description, CFD tool setup and the results for the case of a travelling wave mode with the pure torsion motion of amplitude of 0.5°, Ma = 0.2, reduced frequency of 0.38 and angle of attack +5°.

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13

Kornilov, Vladimir, Ivan Kavun, and Anatoliy Popkov. "Experience of the Using of Cascade Method for Turbulent Boundary-Layer Control Through Air Blowing." Siberian Journal of Physics 9, no. 1 (March 1, 2014): 49–61. http://dx.doi.org/10.54362/1818-7919-2014-9-1-49-61.

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The possibilities of turbulent drag reduction in an incompressible turbulent boundary layer of a flat plate with air blowing through a microperforated surface which consists of sequentially arranged one behind the other self-contained permeable areas were studied. Mass flow rate of air blowing per unit area Q was increased with increasing distance downstream, but in total was not more than 0.0768 kg/s/m2 . A consistent reduction of the local skin friction values along the length of the model, up to 70% at the end of the last active blowing area was shown. The experimental data characterizing the ability to manage a turbulent boundary layer in the ground conditions by passive air overflow generated by the difference between the barometric pressure and the pressure in the wind tunnel test section were obtained

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14

Wolff, Stefan, Stefan Brunner, and Leonhard Fottner. "The Use of Hot-Wire Anemometry to Investigate Unsteady Wake-Induced Boundary-Layer Development on a High-Lift LP Turbine Cascade." Journal of Turbomachinery 122, no. 4 (February 1, 2000): 644–50. http://dx.doi.org/10.1115/1.1311282.

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Recent research has revealed positive effects of unsteady flow on the development of boundary layers in turbine cascades, especially at conditions with a laminar suction side separation bubble at low Reynolds numbers. Compared to steady flow, a reduction of total pressure loss coefficient over a broad range of Reynolds numbers has been shown. Taking into account the positive effects of wake-induced transition already during the design process, new high lift bladings with nearly the same low losses at unsteady inlet flow conditions could be achieved. This leads to a reduction of weight and cost of the whole turbine module for a constant stage loading. Unsteady flow in turbomachines is caused by the relative motion of rotor and stator rows. For simulating a moving blade row upstream of a linear cascade in the High-Speed Cascade Wind Tunnel of the Universita¨t der Bundeswehr Mu¨nchen, a wake generator has been designed and built. The wakes are generated with bars, moving with a velocity of up to 40 m/s in the test section upstream of the cascade inlet plane. Unsteady flow causes the transition on the surface of the suction side of a low-pressure turbine blade to move upstream whenever an incoming wake is present on the surface; moreover, a laminar separation bubble can be diminished or even suppressed. In order to detect the effects of wakes on the boundary layer development a new hot wire data acquisition system is required. Due to the fact that hot wires give a good insight into boundary layer development, a new hot-wire data acquisition system has been set up. The anemometry system can acquire four channels simultaneously, therefore being capable of logging a triple hot-wire sensor and a bar trigger simultaneously. One further channel is utilized for a once-per-revolution trigger. The once-per-revolution trigger is used to start the measurement of one data block. Using the well-established ensemble-averaging technique, 300 ensembles each consisting of five wake passing periods have been acquired. Ensemble averaging can be directly performed without any data reduction. The adaptation of this new hot-wire anemometry data acquisition system to the High-Speed Cascade Wind Tunnel of the Universita¨t der Bundeswehr Mu¨nchen is pointed out. First, results on unsteady periodic boundary layer development of a highly loaded low-pressure turbine cascade under unsteady inlet flow conditions are presented. During the present investigation four boundary layer traverses, ranging from x/lax=0.82 to x/lax=0.99 (suction side), at steady and unsteady inlet flow conditions Ubar=10 m/s at an outlet Reynolds number of Re2th=100,000 have been conducted. [S0889-504X(00)00204-X]

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15

Chen, Ping-Hei, and Jr-Ming Miao. "Effect of Upstream Wake on Shower-Head Film Cooling." International Journal of Rotating Machinery 2, no. 4 (1996): 269–80. http://dx.doi.org/10.1155/s1023621x96000140.

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The present study aims to investigate the effect of an upstream wake on the convective transport phenomena over a turbine blade with shower-head film cooling. A naphthalene sublimation technique was implemented to obtain the detailed mass transfer distributions on both suction and pressure surfaces of the test blade. All mass transfer runs were conducted on a blowing-type wind tunnel with a six-blade linear cascade. The leading edge of the test blade was drilled with three rows of equally spaced injection holes. The upstream wake was simulated by a circular bar with the same diameter as that of the trailing edge of the test blade.The test condition was fixed at Re = 397,000, M = 0.8, and Tu = 0.4% and upstream wakes were generated at four different locations ahead of the blade cascade. Measured results show that there is a difference in mass transfer rate from the case without upstream wake. This difference is greater on the suction side than on the pressure side. The difference results from the interaction between the wake flow that is induced by the upstream wake and the injection flows that are ejected from the multi-rows of injection holes on the test blade. It was also found that the location of upstream wake generation significantly affects the mass transfer distributions on both surfaces of test blade.

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16

SHIBATA, Takanori, Susumu NAKANO, Hideki ONO, Kazuhiko MORISHITA, and Yasuhiro TANI. "Linear Cascade Wind Tunnel Testing of Supersonic Inflow and Outflow Turbine Blades (Test Section Design and Flow Visualization Using Schlieren Techniques)." TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B 79, no. 806 (2013): 2120–33. http://dx.doi.org/10.1299/kikaib.79.2120.

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17

Aberle-Kern, S., R. Niehuis, and T. Ripplinger. "Loss determination at a linear cascade under consideration of thermal effects." Aeronautical Journal 124, no. 1280 (July 6, 2020): 1592–614. http://dx.doi.org/10.1017/aer.2020.57.

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ABSTRACTTargeting higher efficiencies and lower fuel consumption of turbomachines, heat transfer and profile loss are research topics of particular interest. In contrast to that, the interaction of both was, so far, rarely investigated, but gains in importance in recent research activities. The profile loss of engine components can be characterised by the airfoil wakes at the blade rows utilising established measurement and evaluation methods for which an adiabatic flow is typically supposed. To enable the investigation of the influence of heat transfer at the blade on the loss characteristics, a novel evaluation procedure was set up. In addition to the pneumatic data, the total temperature in the airfoil wake at a linear cascade was measured by means of a five-hole probe with an integrated thermocouple. For the evaluation and analysis of these data, different definitions of the loss coefficient were investigated and, finally, extended to account for thermal aspects. Furthermore, established techniques to average the local wake data were applied and compared with special focus to their suitability for non-adiabatic cases. Moreover, an extended version of the mixed-out average as defined by Amecke was utilised applying not only a far-reaching consideration of a temperature gradient but also the inclusion of the third spatial dimension to enable the evaluation of field traverses in addition to single wake traverses. These techniques were applied to wake measurement data from a linear compressor cascade gained in a special test set-up in the high-speed cascade wind tunnel for different operating points and different blade temperatures. The suitability of the new methods could be proven, and initial steps of the aerodynamic analysis of the resulting data are presented. Thereby, the acquired techniques turned out as powerful methods for the evaluation of wake traverses on compressor and turbine cascades under non-adiabatic conditions.

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18

Hobson, G. V., A. J. H. Williams, and H. J. Ganaim Rickel. "Laser-Doppler-Velocimetry Measurements in a Cascade of Compressor Blades at Stall." Journal of Turbomachinery 120, no. 1 (January 1, 1998): 170–78. http://dx.doi.org/10.1115/1.2841378.

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Compressor stall was simulated in the Low-Speed Cascade Wind Tunnel at the Turbopropulsion Laboratory of the Naval Postgraduate School. The test blades were of controlled-diffusion design with a solidity of 1.67, and stalling occurred at 10 deg of incidence above the design inlet air angle. All measurements were taken at a flow Reynolds number, based on chord length, of 700,000. Laser-sheet flow visualization techniques showed that the stalling process was unsteady and occurred over the whole cascade. Detailed laser-Doppler-velocimetry measurements over the suction side of the blades showed regions of continuous and intermittent reverse flow. The measurements of the continuous reverse flow region at the leading edge were the first data of their kind in the leading edge separation bubble. The regions of intermittent reverse flow, measured with laser-Doppler velocimeter, corresponded to the flow visualization studies. Blade surface pressure measurements showed a decrease in normal force on the blade, as would be expected at stall. Data are presented in a form that characterizes the unsteady positive and negative velocities about their mean, for both the continuous reverse flow regions and the intermittent reverse flow regions.

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19

Abuaf, N., R. Bunker, and C. P. Lee. "Heat Transfer and Film Cooling Effectiveness in a Linear Airfoil Cascade." Journal of Turbomachinery 119, no. 2 (April 1, 1997): 302–9. http://dx.doi.org/10.1115/1.2841113.

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A warm (315°C) wind tunnel test facility equipped with a linear cascade of film cooled vane airfoils was used in the simultaneous determination of the local gas side heat transfer coefficients and the adiabatic film cooling effectiveness. The test rig can be operated in either a steady-state or a transient mode. The steady-state operation provides adiabatic film cooling effectiveness values while the transient mode generates data for the determination of the local heat transfer coefficients from the temperature–time variations and of the film effectiveness from the steady wall temperatures within the same aerothermal environment. The linear cascade consists of five airfoils. The 14 percent cascade inlet free-stream turbulence intensity is generated by a perforated plate, positioned upstream of the airfoil leading edge. For the first transient tests, five cylinders having roughly the same blockage as the initial 20 percent axial chord of the airfoils were used. The cylinder stagnation point heat transfer coefficients compare well with values calculated from correlations. Static pressure distributions measured over an instrumented airfoil agree with inviscid predictions. Heat transfer coefficients and adiabatic film cooling effectiveness results were obtained with a smooth airfoil having three separate film injection locations, two along the suction side, and the third one covering the leading edge showerhead region. Near the film injection locations, the heat transfer coefficients increase with the blowing film. At the termination of the film cooled airfoil tests, the film holes were plugged and heat transfer tests were conducted with non-film cooled airfoils. These results agree with boundary layer code predictions.

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20

Ninnemann, Todd, and Wing F. Ng. "Loss Reduction Using Riblets on a Supersonic Through-Flow Fan Blade Cascade." Journal of Fluids Engineering 126, no. 4 (July 1, 2004): 642–49. http://dx.doi.org/10.1115/1.1667883.

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An experimental and computational study to determine the effects of riblets on the performance of the Supersonic Throughflow Fan (STF) cascade blades was performed. The cascade was tested in the Virginia Tech intermittent wind tunnel facility, where the Mach and Reynolds (based on chord) numbers were 2.36 and 4.8×106, respectively. The riblet sheets were symmetric v-grooved type and were applied onto the blade surfaces. Three different riblet heights were tested: 0.023, 0.033, and 0.051 mm. Riblet testing was conducted at design incidence as well as at off-design conditions (incidence angles: +5, −10 deg). Loss coefficients were measured and compared with a control test case where an equivalent thickness of smooth material was applied to the blade. Results show that at the design incidence, the riblet sheet with a height of 0.033 mm provides the optimal benefit, with a reduction of 8.5% in loss coefficient compared to the control case. Smaller effects were measured at the off-design conditions. In addition to the experimental study, a numerical investigation of the riblet effect on the STF cascade was conducted at design incidence. A simple method was developed to model riblet effects due to decrease in turbulent viscous drag and the delay of turbulent transition on the blades. Conclusions from numerical study indicate the 2/3 of the total decrease in losses are the result of delaying the transition location. The final 1/3 decrease in loss coefficient comes from the decrease in turbulent viscous losses.

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21

Varpe, Mahesh, and A. M. Pradeep. "Investigation of the Shear Flow Effect and Tip Clearance on a Low Speed Axial Flow Compressor Cascade." International Journal of Rotating Machinery 2013 (2013): 1–22. http://dx.doi.org/10.1155/2013/490543.

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This paper explores the effect of inlet shear flow on the tip leakage flow in an axial flow compressor cascade. A flow with a high shear rate is generated in the test section of an open circuit cascade wind tunnel by using a combination of screens with a prescribed solidity. It is observed that a stable shear flow of shear rate 1.33 is possible and has a gradual decay rate until 15 times the height of the shear flow generator downstream. The computational results obtained agree well with the available experimental data on the baseline configuration. The detailed numerical analysis shows that the tip clearance improves the blade loading near the tip through the promotion of favorable incidence by the tip leakage flow. The tip clearance shifts the centre of pressure on the blade surface towards the tip. It, however, has no effect on the distribution of end wall loss and deviation angle along the span up to 60% from the hub. In the presence of a shear inflow, the end wall effects are considerable. On the other hand, with a shear inflow, the effects of tip leakage flow are observed to be partly suppressed. The shear flow reduces the tip leakage losses substantially in terms of kinetic energy associated with it.

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22

Du, Hui, Srinath V. Ekkad, Je-Chin Han, and C. Pang Lee. "Detailed Film Cooling Measurements over a Gas Turbine Blade Using a Transient Liquid Crystal Image Technique." International Journal of Rotating Machinery 7, no. 6 (2001): 415–24. http://dx.doi.org/10.1155/s1023621x01000367.

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Detailed heat transfer coefficient and film effectiveness distributions over a gas turbine blade with film cooling are obtained using a transient liquid crystal image technique. The test blade has three rows of film holes on the leading edge and two rows each on the pressure and suction surfaces. A transient liquid crystal technique maps the entire blade midspan region, and helps provide detailed measurements, particularly near the film hole. Tests were performed on a five-blade linear cascade in a low-speed wind tunnel. The mainstream Reynolds number based on cascade exit velocity is5.3×105. Two different coolants (air andCo2) were used to simulate coolant density effect. Coolant blowing ratio was varied between 0.8 and 1.2 for air injection and 0.4–1.2 forCo2injection. Results show that film injection promotes earlier laminar-turbulent boundary layer transition on the suction surface and also enhances local heat transfer coefficients (up to 80%) downstream of injection. An increase in coolant blowing ratio produces higher heat transfer coefficients for both coolants. This effect is stronger immediately downstream of injection holes. Film effectiveness is highest at a blowing ratio of 0.8 for air injection and at a blowing ratio of 1.2 forCo2injection. Such detailed results will help provide insight into the film cooling phenomena on a gas turbine blade.

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23

Baines, N. C., M. L. G. Oldfield, J. P. Simons, and J. M. Wright. "The Aerodynamic Development of a Highly Loaded Nozzle Guide Vane." Journal of Turbomachinery 108, no. 2 (October 1, 1986): 261–68. http://dx.doi.org/10.1115/1.3262046.

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A series of high-pressure turbine nozzle guide vanes has been designed for progressively increasing blade loading and reduction in blade solidity without additional loss penalty. Early members of the series achieved this by changes to the suction surface contour, but for the latest design the pressure surface contour was extensively modified to reduce the velocities on this surface substantially. Cascade testing revealed that this vane had a higher loss than its predecessor, and this appears to be largely due to a long region of boundary layer growth on the suction surface and possibly also an unsteady separation. These tests demonstrated the value of a flattened pitot tube held against the blade surface in determining the boundary layer state. By using a pitot probe of only modest frequency response (of order 100 Hz) it was possible to observe significant qualitative differences in the raw signals from laminar, transitional and turbulent boundary layers, which have previously been observed only with much higher frequency instruments. The test results include a comparison of boundary layer measurements on the same cascade test section in two different high-speed wind tunnels. This comparison suggests that freestream turbulence can have a large effect on boundary layer development and growth.

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24

Bitter, Martin, Michael Hilfer, Tobias Schubert, Christian Klein, and Reinhard Niehuis. "An Ultra-Fast TSP on a CNT Heating Layer for Unsteady Temperature and Heat Flux Measurements in Subsonic Flows." Sensors 22, no. 2 (January 15, 2022): 657. http://dx.doi.org/10.3390/s22020657.

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In this paper, the authors demonstrate the application of a modified Ru(phen)-based temperature-sensitive paint which was originally developed for the evaluation of unsteady aero-thermodynamic phenomena in high Mach number but short duration experiments. In the present work, the modified TSP with a temperature sensitivity of up to −5.6%/K was applied in a low Mach number long-duration test case in a low-pressure environment. For the demonstration of the paint’s performance, a flat plate with a mounted cylinder was set up in the High-Speed Cascade Wind Tunnel (HGK). The test case was designed to generate vortex shedding frequencies up to 4300 Hz which were sampled using a high-speed camera at 40 kHz frame rate to resolve unsteady surface temperature fields for potential heat-transfer estimations. The experiments were carried out at reduced ambient pressure of p∞ = 13.8 kPa for three inflow Mach numbers being Ma∞=[0.3;0.5;0.7]. In order to enable the resolution of very low temperature fluctuations down to the noise floor of 10−5 K with high spatial and temporal resolution, the flat plate model was equipped with a sprayable carbon nanotube (CNT) heating layer. This constellation, together with the thermal sensors incorporated in the model, allowed for the calculation of a quasi-heat-transfer coefficient from the surface temperature fields. Besides the results of the experiments, the paper highlights the properties of the modified TSP as well as the methodology.

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25

Rehder, Hans-Jürgen, and Axel Dannhauer. "Experimental Investigation of Turbine Leakage Flows on the Three-Dimensional Flow Field and Endwall Heat Transfer." Journal of Turbomachinery 129, no. 3 (July 20, 2006): 608–18. http://dx.doi.org/10.1115/1.2720484.

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Within a European research project, the tip endwall region of low pressure turbine guide vanes with leakage ejection was investigated at DLR in Göttingen. For this purpose a new cascade wind tunnel with three large profiles in the test section and a contoured endwall was designed and built, representing 50% height of a real low pressure turbine stator and simulating the casing flow field of shrouded vanes. The effect of tip leakage flow was simulated by blowing air through a small leakage gap in the endwall just upstream of the vane leading edges. Engine relevant turbulence intensities were adjusted by an active turbulence generator mounted in the test section inlet plane. The experiments were performed with tangential and perpendicular leakage ejection and varying leakage mass flow rates up to 2%. Aerodynamic and thermodynamic measurement techniques were employed. Pressure distribution measurements provided information about the endwall and vane surface pressure field and its variation with leakage flow. Additionally streamline patterns (local shear stress directions) on the walls were detected by oil flow visualization. Downstream traverses with five-hole pyramid type probes allow a survey of the secondary flow behavior in the cascade exit plane. The flow field in the near endwall area downstream of the leakage gap and around the vane leading edges was investigated using a 2D particle image velocimetry system. In order to determine endwall heat transfer distributions, the wall temperatures were measured by an infrared camera system, while heat fluxes at the surfaces were generated with electric operating heating foils. It turned out from the experiments that distinct changes in the secondary flow behavior and endwall heat transfer occur mainly when the leakage mass flow rate is increased from 1% to 2%. Leakage ejection perpendicular to the main flow direction amplifies the secondary flow, in particular the horseshoe vortex, whereas tangential leakage ejection causes a significant reduction of this vortex system. For high leakage mass flow rates the boundary layer flow at the endwall is strongly affected and seems to be highly turbulent, resulting in entirely different heat transfer distributions.

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26

Matsunuma, Takayuki. "Effects of the Installation Location of a Dielectric Barrier Discharge Plasma Actuator on the Active Passage Vortex Control of a Turbine Cascade at Low Reynolds Numbers." Actuators 11, no. 5 (May 2, 2022): 129. http://dx.doi.org/10.3390/act11050129.

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Because axial flow turbines are widely used as the main components of jet engines and industrial gas turbines, their energy reduction effect is significant, even with a slight performance improvement. These turbines operate over a wide range of Reynolds numbers. However, at low Reynolds numbers below 1 × 105, the aerodynamic characteristics deteriorate greatly, due to the flow separation of the boundary layer on the blade suction surface and an increase in the secondary flow. In this study, an experiment to reduce the passage vortex was conducted using a dielectric barrier discharge plasma actuator, which is expected to operate with a new innovative active flow control technology. The plasma actuator was installed on the endwall of a linear turbine cascade in the test section of a wind tunnel. From the velocity distribution measured using particle image velocimetry, the secondary flow vector, turbulence intensity, and vorticity were analyzed. The input voltage and frequency of the plasma actuator were fixed at 12 kVp-p and 10 kHz, respectively. In particular, the optimum installation location of the plasma actuator was examined from upstream to mid-passage positions of the turbine cascade (normalized axial location of Z/Cax = −0.35 to 0.51). In addition, the effect of the Reynolds number was examined by varying it between Reout = 1.8 × 104 and 3.7 × 104. From the experimental results, it was found that the optimum location of the plasma actuator was immediately before the blade leading edge (Z/Cax = −0.20 to −0.06). This is because the inlet boundary layer can be accelerated near the blade leading edge, weakening the horseshoe vortex which initially causes the passage vortex. At a higher Reynolds number, the passage vortex suppression effect of the plasma actuator is weakened, because the flow induced by the plasma actuators becomes relatively weaker as the mainstream velocity increases with an increase in the Reynolds number.

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27

Rhee, Dong-Ho, and Hyung Hee Cho. "Local Heat/Mass Transfer Characteristics on a Rotating Blade With Flat Tip in a Low-Speed Annular Cascade—Part II: Tip and Shroud." Journal of Turbomachinery 128, no. 1 (February 1, 2005): 110–19. http://dx.doi.org/10.1115/1.2098767.

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The local heat/mass transfer characteristics on the tip and shroud were investigated using a low speed rotating turbine annular cascade. Time-averaged mass transfer coefficients on the tip and shroud were measured using a naphthalene sublimation technique. A low speed wind tunnel with a single stage turbine annular cascade was used. The turbine stage is composed of sixteen guide plates and blades. The chord length of blade is 150 mm and the mean tip clearance is about 2.5% of the blade chord. The tested Reynolds number based on inlet flow velocity and blade chord is 1.5×105 and the rotational speed of the blade is 255.8 rpm at design condition. The results were compared with the results for a stationary blade and the effects of incidence angle of incoming flow were examined for incidence angles ranging from −15 to +7deg. The off-design test conditions are obtained by changing the rotational speed with a fixed incoming flow velocity. Flow reattachment on the tip near the pressure side edge dominates the heat transfer on the tip surface. Consequently, the heat/mass transfer coefficients on the blade tip are about 1.7 times as high as those on the blade surface and the shroud. However, the heat transfer on the tip is about 10% lower than that for the stationary case due to reduced leakage flow with the relative motion. The peak regions due to the flow reattachment are reduced and shifted toward the trailing edge and additional peaks are formed near the leading edge region with decreasing incidence angles. But, quite uniform and high values are observed on the tip with positive incidence angles. The time-averaged heat/mass transfer on the shroud surface has a level similar to that of the stationary cases.

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28

Radomsky, R. W., and K. A. Thole. "Flowfield Measurements for a Highly Turbulent Flow in a Stator Vane Passage." Journal of Turbomachinery 122, no. 2 (February 1, 1999): 255–62. http://dx.doi.org/10.1115/1.555442.

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Turbine vanes experience high convective surface heat transfer as a consequence of the turbulent flow exiting the combustor. Before improvements to vane heat transfer predictions through boundary layer calculations can be made, we need to understand how the turbulent flow in the inviscid region of the passage reacts as it passes between two adjacent turbine vanes. In this study, a scaled-up turbine vane geometry was used in a low-speed wind tunnel simulation. The test section included a central airfoil with two adjacent vanes. To generate the 20 percent turbulence levels at the entrance to the cascade, which simulates levels exiting the combustor, an active grid was used. Three-component laser-Doppler velocimeter measurements of the mean and fluctuating quantities were measured in a plane at the vane midspan. Coincident velocity measurements were made to quantify Reynolds shear stress and correlation coefficients. The energy spectra and length scales were also measured to give a complete set of inlet boundary conditions that can be used for numerical simulations. The results show that the turbulent kinetic energy throughout the inviscid region remained relatively high. The surface heat transfer measurements indicated high augmentation near the leading edge as well as the pressure side of the vane as a result of the elevated turbulence levels. [S0889-504X(00)02302-3]

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29

Rhee, Dong-Ho, and Hyung Hee Cho. "Local Heat/Mass Transfer Characteristics on a Rotating Blade With Flat Tip in Low-Speed Annular Cascade—Part I: Near-Tip Surface." Journal of Turbomachinery 128, no. 1 (February 1, 2005): 96–109. http://dx.doi.org/10.1115/1.2098756.

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The present study focuses on local heat/mass transfer characteristics on the near-tip region of a rotating blade. To investigate the local heat/mass transfer on the near-tip surface of the rotating turbine blade, detailed measurements of time-averaged mass transfer coefficients on the blade surfaces were conducted using a naphthalene sublimation technique. A low speed wind tunnel with a single stage annular turbine cascade was used. The turbine stage is composed of sixteen guide plates and blades with spacing of 34 mm, and the chord length of the blade is 150 mm. The mean tip clearance is about 2.5% of the blade chord. The tested Reynolds number based on inlet flow velocity and blade chord is 1.5×105 and the rotational speed of blade is 255.8 rpm for the design condition. The result at the design condition was compared with the results for the stationary blade to clarify the rotational effect, and the effects of incoming flow incidence angle were examined for incidence angles ranging from −15 to +7deg. The off-design test condition is obtained by changing the rotational speed maintaining a fixed incoming flow velocity. Complex heat transfer characteristics are observed on the blade surface due to the complicated flow patterns, such as flow acceleration, laminarization, transition, separation bubble and tip leakage flow. The blade rotation causes an increase of the incoming flow turbulence intensity and a reduction of the tip gap flow. At off-design conditions, the heat transfer on the turbine rotor changes significantly due to the flow acceleration/deceleration and the incoming flow angle variation.

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30

Engelmann, David, Martin Sinkwitz, Francesca di Mare, Björn Koppe, Ronald Mailach, Jordi Ventosa-Molina, Jochen Fröhlich, Tobias Schubert, and Reinhard Niehuis. "Near-Wall Flow in Turbomachinery Cascades—Results of a German Collaborative Project." International Journal of Turbomachinery, Propulsion and Power 6, no. 2 (May 8, 2021): 9. http://dx.doi.org/10.3390/ijtpp6020009.

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This article provides a summarizing account of the results obtained in the current collaborative work of four research institutes concerning near-wall flow in turbomachinery. Specific questions regarding the influences of boundary layer development on blades and endwalls as well as loss mechanisms due to secondary flow are investigated. These address skewness, periodical distortion, wake interaction and heat transfer, among others. Several test rigs with modifiable configurations are used for the experimental investigations including an axial low speed compressor, an axial high-speed wind tunnel, and an axial low-speed turbine. Approved stationary and time resolving measurements techniques are applied in combination with custom hot-film sensor-arrays. The experiments are complemented by URANS simulations, and one group focusses on turbulence-resolving simulations to elucidate the specific impact of rotation. Juxtaposing and interlacing their results the four groups provide a broad picture of the underlying phenomena, ranging from compressors to turbines, from isothermal to non-adiabatic, and from incompressible to compressible flows.

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31

A, Mugeshwaran, Guru Prasad Bacha, and Rajkumar S. "Design and experimental analysis of morphing wing based on biomimicry." International Journal of Engineering & Technology 7, no. 3.3 (June 8, 2018): 239. http://dx.doi.org/10.14419/ijet.v7i2.33.14160.

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In this paper narrate about the study of aerodynamics in the multi-section morphing wing variation of baseline configuration to camber con-figuration. In particularly NACA 0012, section tried to morph as NACA 9312 camber section to achieve the lift to drag ratio in the flight condition based on the bio-mimicry. The CAD model and fabricated morphing wing in geometry scale of 20 cm chord and a 36 cm wing-span, with aluminum material ribs divided into 6 sections. Each section was able to rotate approximately 6 degrees without causing a discon-tinuity in the wing surface and also in order avoid the control surface based on the bio mimicry the morphing wing was designed and tested. DC-motor located at main spar with the two equal gear ratio the rib section used to morph the wing through the linear mechanical linkages. The aluminum ribs section are made through the EDM-Wire cut machining process for capable to actuate the morphing wing. In each sec-tion morphing wing can able provide up to 10 percent variation in the symmetrical airfoil to the cambered airfoil. The experimental test of the morphing was carried out in the cascade tunnel by force balancing method and the lift and drag output are compared.

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32

Singh, Arvind, Kevin B. Howard, and Michele Guala. "A measure of scale-dependent asymmetry in turbulent boundary layer flows: scaling and Reynolds number similarity." Journal of Fluid Mechanics 797 (May 24, 2016): 549–63. http://dx.doi.org/10.1017/jfm.2016.294.

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The distribution of temporal scale-dependent streamwise velocity increments is investigated in turbulent boundary layer flows at laboratory and atmospheric Reynolds numbers, using the St. Anthony Falls Laboratory wind tunnel and the Surface Layer Turbulence and Environmental Science Test dataset, respectively. The third-order moments of velocity increments, or asymmetry index $A(a,z)$, is computed for varying wall distance $z$ and time scale separation $a$, where it was observed to leave a robust, distinct signature in the form of a hump, independent of Reynolds number and located across the inertial range. The hump is observed in wall region limited to $z^{+}<5\times 10^{3}$, with a tendency to shift towards smaller time scales as the surface is approached ($z^{+}<70$). Comparing the two datasets, the hump, and its location, are found to obey inner wall scaling and is regarded as a genuine feature of the canonical turbulent boundary layer. The magnitude cumulant analysis of the scale-dependent velocity increments further reveals that intermittency is also enhanced near the wall, in the same flow region where the asymmetry signature was observed. The combination of asymmetry and intermittency is inferred to point at non-local energy transfer and scale coupling across a range of scales. From a turbulent structure perspective, such non-local energy transfer can be seen as the result of strong scale-interaction processes between outer scale motions in the logarithmic layer impacting and distorting smaller scales at the wall, through abrupt energy transfer across scales bypassing the typical energy cascade of the inertial range.

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33

NISHIMURA, Hiroaki. "Wind Tunnel Experiment and Wind Tunnel Test." Wind Engineers, JAWE 39, no. 4 (2014): 333–34. http://dx.doi.org/10.5359/jawe.39.333.

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34

NISHIZAWA, Toshio, Yasuhiko IIDA, and Hiroyuki TAKATA. "Cascade Wind Tunnel Experiment of Stall Flutter." Transactions of the Japan Society of Mechanical Engineers Series B 65, no. 635 (1999): 2309–16. http://dx.doi.org/10.1299/kikaib.65.2309.

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35

NAKAMURA, Osamu. "Wind Tunnel Test for Wind Environment." Wind Engineers, JAWE 34, no. 1 (2009): 18–23. http://dx.doi.org/10.5359/jawe.34.18.

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36

Buffum, D. H., and S. Fleeter. "Wind Tunnel Wall Effects in a Linear Oscillating Cascade." Journal of Turbomachinery 115, no. 1 (January 1, 1993): 147–56. http://dx.doi.org/10.1115/1.2929199.

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Experiments in a linear oscillating cascade reveal that the wind tunnel walls enclosing the airfoils have, in some cases, a detrimental effect on the oscillating cascade aerodynamics. In a subsonic flow field, biconvex airfoils are driven simultaneously in harmonic, torsion-mode oscillations for a range of interblade phase angle values. It is found that the cascade dynamic periodicity—the airfoil-to-airfoil variation in unsteady surface pressure—is good for some values of interblade phase angle but poor for others. Correlation of the unsteady pressure data with oscillating flat plate cascade predictions is generally good for conditions where the periodicity is good and poor where the periodicity is poor. Calculations based upon linearized unsteady aerodynamic theory indicate that pressure waves reflected from the wind tunnel walls are responsible for the cases where there is poor periodicity and poor correlation with the predictions.

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37

Tateishi, Atsushi, Toshinori Watanabe, Takehiro Himeno, and Seiji Uzawa. "Numerical method for an assessment of steady and motion-excited flowfields in a transonic cascade wind tunnel." Journal of the Global Power and Propulsion Society 1 (August 25, 2017): QL9XVI. http://dx.doi.org/10.22261/ql9xvi.

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AbstractThis article presents a numerical method and its application for an assessment of the flow field inside a wind tunnel. A structured computational fluid dynamics (CFDs) solver with overset mesh technique is developed in order to simulate geometrically complex configurations. Applying the developed solver, a whole transonic cascade wind tunnel is modeled and simulated by a two-dimensional manner. The upstream and downstream periodicity of the cascade and the effect of the tunnel wall on the unsteady flow field are focused on. From the steady flow simulations, the existence of an optimum throttle position for the best periodicity for each tailboard angle is shown, which provides appropriate aerodynamic characteristics of ideal cascades in the wind tunnel environment. Unsteady simulations with blade oscillation is also conducted, and the difference in the influence coefficients between ideal and wind tunnel configurations becomes large when the pressure amplitude increases on the lower blades.

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38

Zhou, Qi, Yuxiang Zhu, Yu Wang, and Jiceng Han. "CFD-Based Wind Field Correction Method for Terrain Wind Tunnel Tests." Journal of Physics: Conference Series 2083, no. 3 (November 1, 2021): 032083. http://dx.doi.org/10.1088/1742-6596/2083/3/032083.

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Abstract At present, the wind tunnel test results will have certain deviation and distortion when the wind tunnel test is conducted on certain mountainous terrain with complex local terrain and large variation of wind field characteristics due to the accuracy range of the measuring instruments used in wind tunnel test. In order to correct and obtain correct wind tunnel test results, the wind tunnel tests and numerical simulations were conducted on a super-large bridge in the mountainous area of Southwest China, and the wind parameters of the wind field at the bridge site were obtained. The CFD results were compared with the wind tunnel test results to confirm the credibility of the CFD results; a method was proposed to correct the deviated wind tunnel test data based on the CFD simulation results; the deviated wind tunnel test data were corrected and predicted with the above method, and a more satisfactory correction result was obtained.

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39

Zhang, Jing Hua, Ren Huang Wang, and Hong Wei Yue. "Badminton Performance Test of Wind Tunnel." Advanced Materials Research 860-863 (December 2013): 1517–20. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.1517.

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The badminton wind tunnel experiment quality classification was influenced by a lot of factors, such as the size of the wind tunnel wind speed Settings, the selection of the wind hole diameter size, Experiment parameter Settings of the test system software used standard and experimental error and so on. Therefore, a factorys wind tunnel experimental facility would be used by this paper, in order to make the quality of badminton, wind tunnel wind speed and wind hole diameter are researched further. Through the experiment testing, and combined with badminton wind tunnel experiment of theory knowledge, get the impact of these factors on the quality of badminton classification rule. Theoretical analysis is the same as the result of experiment, which this conclusion is indicated by the experiment that what we do. So as to choose the right wind tunnel device and system software of the test parameters Settings provide certain reference. Also the Badminton the judgment of the quality grade classification standard was provided the important reference frame by it.

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40

Li, Yunhua, Fengjian Teng, and Chaozhi Cai. "Modeling and control of temperature of heat-calibration wind tunnel." Thermal Science 16, no. 5 (2012): 1433–36. http://dx.doi.org/10.2298/tsci1205433l.

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This paper investigates the temperature control of the heat air-flow wind tunnel for sensor temperature-calibration and heat strength experiment. Firstly, a mathematical model was established to describe the dynamic characteristics of the fuel supplying system based on a variable frequency driving pump. Then, based on the classical cascade control, an improved control law with the Smith predictive estimate and the fuzzy proportional-integral-derivative was proposed. The simulation result shows that the control effect of the proposed control strategy is better than the ordinary proportional-integral-derivative cascade control strategy.

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41

ASAMI, Yutaka. "WIND TUNNEL TEST FOR MEMBRANE STRUCTURE." Wind Engineers, JAWE 1999, no. 78 (1999): 49–50. http://dx.doi.org/10.5359/jawe.1999.49.

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42

SASA, Shuichi, Masaaki YANAGIHARA, Seizou SUZUKI, and Fukuo FUKUI. "Cable-Mount Dynamic Wind-Tunnel Test." Journal of the Japan Society for Aeronautical and Space Sciences 42, no. 482 (1994): 159–63. http://dx.doi.org/10.2322/jjsass1969.42.159.

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43

ISHIBASHI, Ryukichi. "Modeling of Wind Breaks for Environmental Wind Tunnel Test." Journal of the Japanese Institute of Landscape Architecture 64, no. 5 (2000): 777–82. http://dx.doi.org/10.5632/jila.64.777.

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44

Petukhov, E. P., Y. B. Galerkin, and A. F. Rekstin. "A Study of Testing Procedures of Vaned Diffusers of a Centrifugal Compressor Stage in a Virtual Wind Tunnel." Proceedings of Higher Educational Institutions. Маchine Building, no. 8 (713) (August 2019): 51–64. http://dx.doi.org/10.18698/0536-1044-2019-8-51-64.

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A mathematical model of a vaned diffuser of a centrifugal compressor stage can be constructed based on the results of mass CFD-calculations, similar to that of vaneless diffusors. The methods for calculating the annular cascade and the straight cascade differ due to the existence of vaneless diffusor sections in front of the cascade and behind it. The rational dimensions of these sections are determined. The calculations of two-dimensional cascades without restricting walls appear to be irrational. The calculation is effective for a sector with one vane channel, a moderate number of cells, and the turbulence model k–ε. Averaging the flow parameters at the blade cascade exit leads to ambiguous results. To calculate the characteristics of the blade cascade, the parameters in a section with a diameter equal to 1.85 of the diameter of the blade cascade exit should be used. In domestic and foreign literature, it is customary to emphasize the effectiveness of the CFD methods that replace physical experiments. Calculations of the compressor stages are called virtual rig testing, while those of the blade cascade are known as virtual wind tunnel testing. To study stationary flow, as a virtual wind tunnel, it suffices to consider the blade cascade itself, the preceding and the subsequent vaneless spaces.

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45

Buffum, D. H., and S. Fleeter. "Effect of Wind Tunnel Acoustic Modes on Linear Oscillating Cascade Aerodynamics." Journal of Turbomachinery 116, no. 3 (July 1, 1994): 513–24. http://dx.doi.org/10.1115/1.2929440.

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The aerodynamics of a biconvex airfoil cascade oscillating in torsion is investigated using the unsteady aerodynamic influence coefficient technique. For subsonic flow and reduced frequencies as large as 0.9, airfoil surface unsteady pressures resulting from oscillation of one of the airfoils are measured using flush-mounted high-frequency-response pressure transducers. The influence coefficient data are examined in detail and then used to predict the unsteady aerodynamics of a cascade oscillating at various interblade phase angles. These results are correlated with experimental data obtained in the traveling-wave mode of oscillation and linearized analysis predictions. It is found that the unsteady pressure disturbances created by an oscillating airfoil excite wind tunnel acoustic modes, which have detrimental effects on the experimental results. Acoustic treatment is proposed to rectify this problem.

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46

Stroub, Robert H., Larry A. Young, Charles N. Keys, and Matthew H. Cawthorne. "Free-Tip Rotor Wind Tunnel Test Results." Journal of the American Helicopter Society 31, no. 3 (July 1, 1986): 19–26. http://dx.doi.org/10.4050/jahs.31.19.

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47

Stroub, Robert H., Larry A. Young, Charles N. Keys, and Matthew H. Cawthorne. "Free‐Tip Rotor Wind Tunnel Test Results." Journal of the American Helicopter Society 31, no. 3 (July 1, 1986): 19–26. http://dx.doi.org/10.4050/jahs.31.3.19.

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48

Jin, Dun, Yue Ming Yang, Jie Wu, Li Min Song, and Song Li. "Static Force Measurement Technology Wind Tunnel Test." Applied Mechanics and Materials 423-426 (September 2013): 1689–92. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.1689.

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Static force measurement aerodynamic wind tunnel test data provided by the aircraft normally used to predict the stall characteristics, predicted aircraft deviated,spin Sensitivities, numerical simulation of aircraft stall, spin dynamics and so on. Based on practical flight, the paper analyzed the harm of limit state flight-spin to the flight safe, emphasized the static force test techniques at high angles of attack, and obtained a series of aerodynamic test date, managed them to spin prediction analysis.

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49

An, Young-Gab, and Rho-Shin Myong. "Scaling Methods for Icing Wind Tunnel Test." Journal of the Korean Society for Aeronautical & Space Sciences 40, no. 2 (February 1, 2012): 146–56. http://dx.doi.org/10.5139/jksas.2012.40.2.146.

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50

Wang, Weihua, Haili Liao, Mingshui Li, and Hanjie Huang. "Similarity Study on Snowdrift Wind Tunnel Test." Open Journal of Civil Engineering 03, no. 03 (2013): 13–17. http://dx.doi.org/10.4236/ojce.2013.33b003.

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