scholarly journals Study on Waves Generated by a Planing Flat Plate-V : Experiment of Pressure Distribution Measurement on a Planing Flat Plate of Finite Span

1995 ◽  
Vol 92 (0) ◽  
pp. 157-166
Author(s):  
Shigeaki SHIOTANI
1967 ◽  
Vol 89 (1) ◽  
pp. 103-108 ◽  
Author(s):  
A. F. Emery ◽  
J. A. Sadunas ◽  
M. Loll

The heat transfer and pressure distribution in a rectangular cavity in a Mach 3 flow were investigated for a rectangular and an inverted-wedge recompression step. Noticeable differences between the results for the two steps were found in the recovery factors, but no real differences were detected in the heat-transfer coefficients or the velocity profiles. Heat-transfer coefficients in the cavity were determined by transient techniques and were found to range from 50 to 110 percent of the flat-plate value just prior to the expansion step.


Author(s):  
M. Deinert ◽  
J. Hourmouziadis

This study gives a detailed experimental evaluation of film cooling characteristics in unsteady flow with a separation bubble. The research project is divided into two phases. In the first phase, which is presented here, only the variation of the velocity caused by upstream blades is simulated in the experiments while the free-stream turbulence intensity is retained at a constant low level. The experiments are carried out on a flat plate with superimposed pressure distribution typical of turbine blading. A contoured wall opposite the flat plate generates this pressure distribution with a strong adverse pressure gradient, which induces a separation bubble in the middle of the plate. The measurements are conducted in an open-circuit, low-speed, suction-type wind tunnel, which can generate periodically pulsating flow. The flat plate is 1000 mm in length and has a width of 400 mm. The cooling air enters the test section through a row of 7 cylindrical film-cooling holes with sharp edges and an inclination angle of 35 degrees. The film cooling holes, which are 8 mm in diameter and have a pitch to diameter ratio of 3:1, are located in the middle of the flat plate. The main objective is to investigate the influence of the separation bubble on the cooling air flow and different film cooling parameters under periodically unsteady flow conditions. Therefore, measurements of the flow velocity and temperature using hot and cold wire anemometry for different boundary conditions were carried out. The results show that the periodic changes of size and shape of the separation bubble in a film cooled flow field under unsteady flow conditions are still dominated by the superimposed periodically changing pressure distribution. The incoming cooling air influences the separation bubble in two ways. On the one hand, the separation bubble is displaced by the film cooling jet, which means that it is only present upstream of the air injection point and on the other hand the separation bubble is thicker directly in front of the incoming film cooling jet because of the superimposed pressure field upstream of the jet. The results of flow temperature measurements show a small low-temperature area upstream of the film cooling jet at the position of the separation bubble.


2006 ◽  
Vol 2006.12 (0) ◽  
pp. 345-346
Author(s):  
Hiromasa SUZUKI ◽  
Junjiro IWAMOTO ◽  
Kousyou MOTOHASHI

Author(s):  
V. Nagabhushana Rao ◽  
P. G. Tucker ◽  
R. J. Jefferson-Loveday ◽  
J. D. Coull

Modern ‘high-lift’ blade designs incorporated into the low pressure turbine (LPT) of aero-engines typically exhibit a separation bubble on the suction surface of the airfoil. The size of the bubble and the loss it generates is governed by the transition process in the separated shear layer. However, the wakes shed by the upstream blade rows, the turbulent fluctuations in the free-stream and the roughness over the blade complicates the transition process. The current paper numerically investigates the transition of a separated shear layer over a flat plate with an elliptic leading edge using large eddy simulations (LES). The upper wall of the test section is inviscid and specifically contoured to impose a streamwise pressure distribution over the flat plate to simulate the suction surface of a LPT blade. The influences of free-stream turbulence (FST), periodic wake passing and streamwise pressure distribution (blade loading) are considered. The simulations were carried out at a Reynolds number of 83,000 based on the length of the flat plate (S0 = 0.5m) and the velocity at the nominal trailing edge (UTE ∼ 2.55 m/s). A high turbulence intensity of 4% and a dimensionless wake passing frequency (fr = fwakeS0/UTE, where fwake is the dimensional wake frequency) of 0.84 is chosen for the study. Two different distributions representative of a ‘high-lift’ and an ‘ultra-high-lift’ turbine blade are examined. An in-house, high order, flow solver is used for the Large Eddy Simulations (LES). The Variational Multi-scale approach is used to account for the sub-grid scale stresses. Results obtained from the current LES compare favorably with the extensive experimental data previously obtained for the test cases considered. The LES results are then used to further explore the flow physics involved in the transition process, in particular the role of Klebanoff streaks and their influence on performance. The additional effect of surface roughness of the blade has also been studied for one of the blade loadings. The benefit that roughness can offer for highly loaded turbine blades is demonstrated.


2001 ◽  
Vol 65 (12) ◽  
pp. 2597-2603 ◽  
Author(s):  
Kaoru KOHYAMA ◽  
Tomoko SAKAI ◽  
Teruaki AZUMA ◽  
Toru MIZUGUCHI ◽  
Ikuo KIMURA

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