Laminar-flow instrumentation for wind-tunnel and flight experiments

1993 ◽  
Vol 30 (2) ◽  
pp. 192-200 ◽  
Author(s):  
Wolfgang Nitsche ◽  
Joachim Szodruch
Keyword(s):  
Wind Tunnel ◽  
Laminar Flow

scholarly journals Fabrication and Hypersonic Wind Tunnel Validation of a MEMS Skin Friction Sensor Based on Visual Alignment Technology

Sensors ◽  
2019 ◽  
Vol 19 (17) ◽  
pp. 3803
Author(s):  
Xiong Wang ◽  
Nantian Wang ◽  
Xiaobin Xu ◽  
Tao Zhu ◽  
Yang Gao
Keyword(s):  
Wind Tunnel ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Skin Friction ◽  
Flow Conditions ◽  
Friction Coefficients ◽  
Hypersonic Wind Tunnel ◽  
Laminar Flow Conditions ◽  
Turbulent Flow Conditions ◽  
Better Than

MEMS-based skin friction sensors are used to measure and validate skin friction and its distribution, and their advantages of small volume, high reliability, and low cost make them very important for vehicle design. Aiming at addressing the accuracy problem of skin friction measurements induced by existing errors of sensor fabrication and assembly, a novel fabrication technology based on visual alignment is presented. Sensor optimization, precise fabrication of key parts, micro-assembly based on visual alignment, prototype fabrication, static calibration and validation in a hypersonic wind tunnel are implemented. The fabrication and assembly precision of the sensor prototypes achieve the desired effect. The results indicate that the sensor prototypes have the characteristics of fast response, good stability and zero-return; the measurement ranges are 0–100 Pa, the resolution is 0.1 Pa, the repeatability accuracy and linearity are better than 1%, the repeatability accuracy in laminar flow conditions is better than 2% and it is almost 3% in turbulent flow conditions. The deviations between the measured skin friction coefficients and numerical solutions are almost 10% under turbulent flow conditions; whereas the deviations between the measured skin friction coefficients and the analytical values are large (even more than 100%) under laminar flow conditions. The error resources of direct skin friction measurement and their influence rules are systematically analyzed.

Aerodynamic and Transition Analysis of the Hybrid Laminar Flow ControlWing at ARA Wind Tunnel

2019 ◽  
Author(s):  
Andrea Ciarella ◽  
Simon Lawson ◽  
Peter Wong ◽  
Mohammed S. Mughal
Keyword(s):  
Wind Tunnel ◽  
Laminar Flow ◽  
Transition Analysis

Transition detection for laminar flow aircraft using microphones beneath the surface of laser drilled suction panels

2000 ◽  
Vol 214 (3) ◽  
pp. 143-155
Author(s):  
R V Barrett
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Laminar Flow ◽  
Reynolds Numbers ◽  
Suction Surface ◽  
Microphone Signal ◽  
High Background ◽  
Low Reynolds Numbers ◽  
High Background Noise ◽  
Suction Flow

The possibility of detecting transition through the very small laser drilled perforations in panels representing the suction surface of a hybrid laminar flow aircraft is examined. The method uses miniature microphones to detect changes to the noise received from the boundary layer. Tests using a flat plate rig in a low-turbulence wind tunnel at Reynolds numbers up to 3.8 million per metre, demonstrate that the boundary layer state can be defined in this manner, most simply through measurement of the root mean square (r.m.s.) of the microphone signal. It is shown that the r.m.s. reaches a peak in the transition zone and that when the boundary layer is fully turbulent the value is still significantly higher than it was before transition. Porosity in the range 0.8-6.4 percent was examined, with nominal hole diameters of 0.06 and 0.10 mm in 0.9 mm thick laser drilled suction surface specimens. Suction flow through the surface was found not adversely to affect the operation of the system. The experiment was limited to low Reynolds numbers because the high background noise in the wind tunnel made detection of the boundary layer element of the signal increasingly difficult to define as speed increased. It is considered that test in flight will be needed to prove fully the validity of the method. A preliminary design of an installation for this purpose is suggested that allows the suction flow to be maintained over the measuring region.

Lift-to-drag ratio and laminar flow control of a morphing laminar wing in a wind tunnel

2011 ◽  
Vol 20 (3) ◽  
pp. 035019 ◽  
Author(s):  
Daniel Coutu ◽  
Vladimir Brailovski ◽  
Patrick Terriault ◽  
Mahmoud Mamou ◽  
Youssef Mébarki ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Laminar Flow ◽  
Flow Control ◽  
Laminar Flow Control ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Sting-free measurements of sphere drag in laminar flow

1972 ◽  
Vol 54 (3) ◽  
pp. 385-392 ◽  
Author(s):  
M. Vlajinac ◽  
E. E. Covert
Keyword(s):  
Wind Tunnel ◽  
Laminar Flow ◽  
Drag Coefficient ◽  
Primary Source ◽  
Reynolds Numbers ◽  
Range Data ◽  
Tunnel Wall ◽  
Balance System ◽  
Flow Drag ◽  
Sphere Drag

An aerodynamic investigation was conducted to determine the laminar-flow drag coefficient of spheres of various sizes in a subsonic wind tunnel. The tests were conducted using the M.I.T.-N.A.S.A. prototype magnetic-balance system. By measuring the drag of different sized spheres without model support interference the tunnel wall effect can be deduced. The present results indicate that the classical wind tunnel correction does not completely account for the effects of model size and wall interference. That is, the corrected drag coefficient data for the different sphere sizes differ among themselves in the region of Reynolds number overlap.A comparison of the present sphere drag results with those of numerous other investigations including free-flight and ballistic-range data is given. The drag coefficients presented here are slightly lower than those of other workers for Reynolds numbers ranging from 20 000 to 150 000, but fall between the limits of experimental scatter for Reynolds numbers from 150 000 to 260 000.An analysis of the estimated error in the present data indicates the primary source to be measurement of the wind tunnel parameters rather than errors resulting from the balance system.

scholarly journals Structural Deformation of a Running Wind Tunnel Measured By Optical Scanning

2020 ◽  
Vol 70 (2) ◽  
pp. 181-196
Author(s):  
Yanovych Vitalii ◽  
Duda Daniel
Keyword(s):  
Wind Tunnel ◽  
Laminar Flow ◽  
Structural Deformation ◽  
Wind Tunnels ◽  
Structural Elements ◽  
Airflow Velocity ◽  
Pressure Drops ◽  
Optical Scanning ◽  
Mutual Displacement ◽  
Structural Parts

AbstractNowadays, the development of wind tunnels for the study of various aerodynamic phenomena is actively developing. It is possible to generate a highly laminar flow only under the condition of structural stability of the construction parts of the wind tunnel under the action of sharp pressure drops. The aim of this research is to investigate the deformation and displacement of the structural parts of the developed wind tunnel capacity of 55 kW depending on the velocity of the generated airflow. To estimate the amount of deformation and mutual displacement of the structural elements of the wind tunnel depending on the airflow velocity, we used the ARAMIS optical system.

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