scholarly journals Effect of a Boundary Layer Leak Slot on Improving the Test Section Flow Quality in an Open Return Meteorological Wind Tunnel

2006 ◽  
Vol 56 ◽  
pp. 1-8
Author(s):  
Nobuyuki kinoshita
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Test Section ◽  
Flow Quality

A Small Wind Tunnel Significantly Improved by a Multi-Purpose, Two-Flexible-Wall Test Section

1994 ◽  
Vol 116 (3) ◽  
pp. 419-423 ◽  
Author(s):  
P. Kankainen ◽  
E. Brundrett ◽  
J. A. Kaiser
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Test Section ◽  
Side Wall ◽  
Reynolds Numbers ◽  
Free Data ◽  
Wall Panels ◽  
Testing Data ◽  
Flexible Wall ◽  
Flow Quality

A small open-return wind tunnel has been renovated to include a longer test section with a flexible roof and floor and improved entrance flow quality. The flexible-wall test section allows models with up to 30 percent nominal blockage to be tested, resulting in a significant increase in the maximum attainable Reynolds numbers. Interchangeable rigid side-wall panels allow flexibility of application which is essential for a university wind tunnel facility. Configurations have been developed for automotive, aerodynamic and atmospheric-boundary-layer testing. Data acquisition and wall positioning are at an economical semi-automated level of operation. The flexible-wall concept has been well-documented previously, and provides interference-free data without flow pattern assumptions after a few iterations of the roof and floor shape. Representative data are presented for a circular cylinder and an airfoil.

Design and Performance of a Hypersonic Wind Tunnel

2017 ◽  
Author(s):  
Jesse Maxwell
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
Wind Tunnel ◽  
Test Section ◽  
Dynamic Pressure ◽  
Continuous Variation ◽  
Axisymmetric Nozzle ◽  
Aspect Ratios ◽  
Tunnel Design ◽  
Flow Quality

A moveable block planar nozzle wind tunnel design from the University of Michigan in 1955 was shown with previous analysis to operate between Mach 1 and at least Mach 6.3 for mid-size test sections, with continuous variation in Mach number and accounting for limitations governed by supply temperature and pressure, liquefaction, flow rate, and flow quality for a desired dynamic pressure or Reynolds number. The moveable block planar nozzle design allows for continuous variation of Mach number, based on a Method of Characteristics solution to a convergent-divergent nozzle with a boundary layer correction. The present work summarizes the design considerations and hardware performance requirements for such a tunnel in the blowdown configuration, with a comparison between cold and hot operation for various test section sizes and supply conditions. The flow quality is compared between a two planar nozzles and an axisymmetric nozzle for a 12×12[in] test section, the effect of physical scaling on flow quality and boundary layer encroachment is investigated across scales of 1×1” to 12×12” test sections at Mach 5, and the merits of planar nozzle aspect ratios greater than unity are presented and discussed.

Air flow quality analysis of an open-circuit boundary layer wind tunnel and comparison with a closed-circuit wind tunnel

2020 ◽  
Vol 32 (12) ◽  
pp. 125120
Author(s):  
María Jiménez-Portaz ◽  
Luca Chiapponi ◽  
María Clavero ◽  
Miguel A. Losada
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Air Flow ◽  
Open Circuit ◽  
Closed Circuit ◽  
Quality Analysis ◽  
Flow Quality

scholarly journals Simulations of the Atmospheric Boundary Layer in a Wind Tunnel with Short Test Section

2013 ◽  
Vol 5 (3) ◽  
pp. 305-314 ◽  
Author(s):  
Luciana Bassi Marinho Pires ◽  
Igor Braga De Paula ◽  
Gilberto Fisch ◽  
Ralf Gielow ◽  
Roberto Da Mota Girardi
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Atmospheric Boundary Layer ◽  
Test Section ◽  
Short Test

Control of separation in the concave portion of contraction to improve the flow quality

2009 ◽  
Vol 113 (1141) ◽  
pp. 177-182 ◽  
Author(s):  
K. Ghorbanian ◽  
M. R. Soltani ◽  
M. D. Manshadi ◽  
M. Mirzaei
Keyword(s):  
Wind Tunnel ◽  
Pressure Distribution ◽  
Turbulence Intensity ◽  
Test Section ◽  
Adverse Pressure Gradient ◽  
Wind Tunnel Experiments ◽  
Free Stream Turbulence ◽  
Static Pressure Distribution ◽  
Subsonic Wind Tunnel ◽  
Flow Quality

AbstractSubsonic wind tunnel experiments were conducted to study the effect of forced transition on the pressure distribution in the concave portion of contraction. Further more, the effect of early transition on the turbulence level in the test section of the wind tunnel is studied. Measurements were performed by installing several trip strips at two different positions in the concave portion of the contraction. The results show that installation of the trip strips, have significant effects on both turbulence intensity and on the pressure distribution. The reduction in the free stream turbulence as well as the wall static pressure distribution varied significantly with the location of the trip strip. The results confirm the significant impact of the tripped boundary layer on the control of adverse pressure gradient. The trip strip atX/L= 0.115 improves pressure distribution in contraction and reduces turbulence intensity in the test section, considerably.

A new boundary layer wind tunnel

1988 ◽  
Vol 92 (916) ◽  
pp. 224-229
Author(s):  
P. E. Roach
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Test Section ◽  
Gas Turbines ◽  
Large Scale ◽  
Free Stream ◽  
Boundary Layer Transition ◽  
Layer Transition ◽  
Free Stream Turbulence ◽  
Dimensional Boundary

Summary The procedures employed for the design of a closed-circuit, boundary layer wind tunnel are described. The tunnel was designed for the generation of relatively large-scale, two-dimensional boundary layers with Reynolds numbers, pressure gradients and free-stream turbulence levels typical of the turbomachinery environment. The results of a series of tests to evaluate the tunnel performance are also described. The flow in the test section is shown to be highly uniform and steady, with very low (natural) free-stream turbulence intensities. Measured boundary layer mean and fluctuating velocity profiles were found to be in good agreement with classical correlations. Test-section free-stream turbulence intensities are presented for grid-generated turbulence: agreement with expectation is again found to be good. Immediate applications to the tunnel include friction drag reduction and boundary layer transition studies, with future possibilities including flow separation and other complex flows typical of those found in gas turbines.

scholarly journals Validation of a laminar-turbulent transition prediction technique for a swept-wing boundary-layer flow

2021 ◽  
Vol 2057 (1) ◽  
pp. 012081
Author(s):  
A V Boiko ◽  
V I Borodulin ◽  
A V Ivanov ◽  
S V Kirilovskiy ◽  
D A Mischenko ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Test Section ◽  
Wind Tunnel Test ◽  
Cross Flow ◽  
Infrared Camera ◽  
Main Flow ◽  
Swept Wing ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

Abstract The laminar-turbulent transition in the boundary layer of a 45° swept wing model installed at zero attack angle in the test section of a subsonic wind-tunnel was detected with the help of an infrared camera. The camera recorded sequences of frames, the evolution of the preheated model surface temperature acquired and used for differentiating between the laminar and turbulent regions. The transition onset was evaluated at both sides of the model. Corresponding main flow computations in the virtual wind tunnel test section were performed at the same flow conditions with ANSYS Fluent. The computed main-flow velocity profiles along inviscid streamlines were used for analysis of hydrodynamic stability of the boundary layer with respect to Tollmien-Schlichting waves and stationary cross-flow vortices to obtain N-factor distributions along the model chord. A comparison of the experimental and the computed transition onsets was performed.

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