Particle image velocimetry and laser Doppler anemometry experimental studies of a compressible short take-off and vertical landing ground vortex flow

2002 ◽  
Vol 216 (4) ◽  
pp. 171-187 ◽  
Author(s):  
N J Lawson ◽  
J M Eyles ◽  
K Knowles
Keyword(s):  
Particle Image Velocimetry ◽  
Vortex Flow ◽  
Particle Image ◽  
Laser Doppler Anemometry ◽  
Cross Flow ◽  
Laser Doppler ◽  
Data Set ◽  
Image Velocimetry ◽  
Vertical Landing ◽  
Dominant Frequencies

A particle image velocimetry (PIV) and laser Doppler anemometry (LDA) study of a scaled short take-off and vertical landing (STOVL) ground vortex flow is presented. The scaled flow features a compressible impinging jet in cross-flow with a moving ground plane. Mean and transient PIV and LDA velocity data are recorded from the ground vortex about the jet centre-line over a range of nozzle pressure ratios (NPR s) from 2.3 to 3.7, nozzle height—diameter ratios ( h/dn) from 3 to 10 (where dn = 12.7 mm) and cross-flow velocities (V∞) from 10 to 20 m/s, corresponding to effective velocity ratios of 19 < Ve−1 < 38. For each condition, 72 PIV vector maps were taken from the ground vortex region to generate an instantaneous and time-average data set. From the instantaneous data, a cinematic sequence was used to track the ground vortex position, which was found to fluctuate longitudinally by a root mean square distance of up to 4.47 dn and vertically by up to 2.18 dn. From the time-averaged PIV measurements, selected LDA pointwise data were taken at the average ground vortex core. Subsequent spectral analysis of the PIV time series showed the ground vortex position to fluctuate at dominant frequencies of between 2.5 and 5 Hz while the LDA data showed the velocity to fluctuate by dominant frequencies ranging between 1 and 30 Hz.

Vortex flow and lift generation of a non-slender reverse delta wing

2016 ◽  
Vol 231 (13) ◽  
pp. 2438-2451
Author(s):  
T Lee ◽  
LS Ko
Keyword(s):  
Particle Image Velocimetry ◽  
Lift Force ◽  
Vortex Flow ◽  
Particle Image ◽  
Delta Wing ◽  
Lower Surface ◽  
Force Balance ◽  
Flow Parameters ◽  
Image Velocimetry ◽  
Spanwise Vortex

The vortex flow and lift force generated by a 50°-sweep non-slender reverse delta wing were investigated via particle image velocimetry, together with flow visualization and force balance measurement, at Re = 11,000. The non-slender reverse delta wing produced a delayed stall but a lower lift compared to its delta wing counterpart. The stalling mechanism was also found to be triggered by the disruption of the multiple spanwise vortex filaments developed over the upper wing surface. The vortex flowfield was, however, characterized by the co-existence of reverse delta wing vortices and multiple shear-layer vortices. The outboard location of the reverse delta wing vortex further implies that the lift force is mainly generated by the wing lower surface while the upper surface acts as a wake generator. The spatial progression of the flow parameters of the vortex generated by the non-slender reverse delta wing as a function of α was also discussed.

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