A study of base pressure near the trailing edge of an axisym-metrical body in supersonic flow

1966 ◽  
Vol 2 (6) ◽  
pp. 61-64 ◽  
Author(s):  
Yu. A. Panov ◽  
A. I. Shvets
Keyword(s):  
Supersonic Flow ◽  
Base Pressure ◽  
Trailing Edge

The effect of base bleed on vortex shedding and base pressure in compressible flow

1981 ◽  
Vol 110 ◽  
pp. 273-292 ◽  
Author(s):  
F. Motallebi ◽  
J. F. Norbury
Keyword(s):  
Supersonic Flow ◽  
Compressible Flow ◽  
Vortex Shedding ◽  
Transonic Flow ◽  
Vortex Formation ◽  
Base Pressure ◽  
Trailing Edge ◽  
Blunt Trailing Edge ◽  
Base Bleed ◽  
The Relationship

Experiments have been carried out to investigate the phenomenon of vortex shedding from the blunt trailing edge of an aerodynamic body in transonic and supersonic flow. The effect of a discharge of bleed air from a slot in the trailing edge has been included and the relationship between the vortex formation and base pressure has been considered.In transonic flow a small amount of bleed air was found to produce a rearward shift in the point of origin of the vortices with a consequent substantial increase in base pressure. The effect was less marked in supersonic flow. At higher rates of bleed two different regimes of vortex shedding were identified and increase in bleed rate caused a reduction in base pressure. For bleed rates giving near-maximum base pressure no vortex shedding occurred.

Experimental and Numerical Investigation on the Performance of a Family of Three HP Transonic Turbine Blades

2004 ◽  
Author(s):  
D. Corriveau ◽  
S. A. Sjolander
Keyword(s):  
Flow Velocity ◽  
Turbine Blades ◽  
Suction Side ◽  
Experimental Results ◽  
Base Pressure ◽  
Suction Surface ◽  
Trailing Edge ◽  
Lower Base ◽  
Shock System ◽  
Transonic Turbine

Experimental results concerning the performance of three high-pressure (HP) transonic turbine blades having fore-, aft- and mid-loadings have been presented previously by Corriveau and Sjolander [1]. Results from that study indicated that by shifting the loading towards the rear of the airfoil, improvements in loss performance of the order of 20% could be obtained near the design Mach number. In order to gain a better understanding of the underlying reasons for the improved loss performance of the aft-loaded blade, additional measurements were performed on the three cascades. Furthermore, 2-D numerical simulations of the cascade flow were performed in order to help in the interpretation of the experimental results. Based on the analysis of additional wake traverse data and base pressure measurements combined with the numerical results, it was found that the poorer loss performance of the baseline mid-loaded profile compared to the aft-loaded blade could be traced back to the former’s higher rear suction side curvature. The presence of higher rear suction surface curvature resulted in higher flow velocity in that region. Higher flow velocity at the trailing edge in turn contributed to reducing the base pressure. The lower base pressure at the trailing edge resulted in a stronger trailing edge shock system for the mid-loaded blade. This shock system increased the losses for the mid-loaded baseline profile when compared to the aft-loaded profile.

High-Speed Visualization of the Oscillatory Supersonic Flow Over a Rectangular Cavity

2011 ◽  
Author(s):  
Taro Handa ◽  
Hiroaki Miyachi ◽  
Hatsuki Kakuno ◽  
Takaya Ozaki
Keyword(s):  
Supersonic Flow ◽  
Pressure Wave ◽  
High Speed ◽  
Pressure Oscillation ◽  
Rectangular Cavity ◽  
Schlieren Method ◽  
Trailing Edge ◽  
The Relationship ◽  
Type Pressure ◽  
Semiconductor Type

A mechanism of cavity-induced pressure oscillation in supersonic flows is not well understood in spite of a lot of former investigations. Especially, the process by which the pressure wave is generated and the path of the pressure wave propagating inside the cavity remain unclear. In order to clarify these, the oscillatory behaviors in the supersonic flow over a rectangular cavity are visualized by the schlieren method with a high-speed camera in the present study. The inlet Mach number of the flow is 1.68. The length and depth of the cavity are 14.0mm and 11.7mm respectively; i.e., the length-to-depth ratio of the cavity is 1.20. The pressure oscillation near the trailing edge of the cavity is also measured by use of the semiconductor-type pressure transducer simultaneously with the visualization. As a result, the pressure waves propagating inside as well as outside the cavity are successfully visualized. In addition, the relationship between the shear layer displacement, pressure wave generation and pressure oscillation at the trailing edge of the cavity are clarified experimentally.

The Effect of Sting Diameter and Length on Base Pressure at M = 3·88

1968 ◽  
Vol 19 (4) ◽  
pp. 368-374 ◽  
Author(s):  
Walter R. Sieling
Keyword(s):  
Supersonic Flow ◽  
Axisymmetric Body ◽  
Base Pressure ◽  
Base Diameter ◽  
Apparent Change

SummaryThe effects of sting diameter and cylindrical protuberance length on the base pressure of an axisymmetric body in a turbulent supersonic flow are experimentally determined. It is found that the change in base pressure due to the presence of the sting is greater than 4 per cent when the ratio of sting diameter to base diameter is 0·150 or greater. When the ratio of cylindrical protuberance length to base diameter is greater than 1·3 there is no apparent change in base pressure with a change in length. However, when this ratio is less than 1·3, the base pressure varies greatly with length.

An Investigation of the Flow around Rectangular Cylinders

1972 ◽  
Vol 23 (3) ◽  
pp. 229-237 ◽  
Author(s):  
P W Bearman ◽  
D M Trueman
Keyword(s):  
Drag Coefficient ◽  
Strouhal Number ◽  
Pressure Coefficient ◽  
Base Pressure ◽  
Trailing Edge ◽  
Rectangular Cylinders

SummaryMeasurements are presented of the base pressure coefficient, drag coefficient and Strouhal number of rectangular cylinders. The results confirm a finding in Japan that the drag coefficient rises to nearly 3 when the depth of the section is just over half the width. The flow around the sections is found to be strongly influenced by the presence of the trailing-edge corners.

Effect of Unguided Turning Angle and Trailing Edge Shape on Cooled Blade Loss

2014 ◽  
Author(s):  
Andrey Granovskiy ◽  
Mikhail Kostege ◽  
Vladimir Vassiliev
Keyword(s):  
Gas Turbines ◽  
Numerical Procedure ◽  
Suction Side ◽  
Aerodynamic Characteristics ◽  
Base Pressure ◽  
Trailing Edge ◽  
Flow Angle ◽  
Generation Mechanisms ◽  
Cooled Blade ◽  
Blade Loss

A significant part of the overall loss in modern gas turbines is the trailing edge loss. This loss is, more strongly than other constituents, affected by operation, because the trailing edge can significantly change its shape due to degradation. Also by manufacturing of new parts and reconditioning the same tolerances as in other parts of blade lead to higher deviations of aerodynamic characteristics. Therefore the understanding of trailing edge loss generation mechanisms is of utmost importance for a sound blade design. In this work the results of combined experimental and numerical investigation of the trailing edge impact on the transonic cooled blade loss are presented. This study comprises the investigation of the unguided flow angle and the trailing edge shape on the profile losses and a base pressure. The unguided flow angle characterizes the curvature distribution on the aerofoil suction side. The numerical and experimental investigation of transonic cooled turbine cascades have shown that the increase of the unguided flow angle results in loss reduction due to increase of the base pressure downstream of the trailing edge. At the same time the deviation of the trailing edge from a round shape has detrimental effect on performance and conducted investigations allow quantification of this effect. The measurements were performed in a transonic wind tunnel and numerical simulations were done using in-house 2D Navier-Stokes code. The comparison of calculations with measurements showed that they are in reasonable agreement. The validated numerical procedure has been used for demonstration of possibility to reduce loss in aerofoil with thick trailing edge by tuning of the unguided flow angle. The use of the thick trailing edges at HP cooled turbines reduces restriction on tolerances, improves of manufacturability and reduces cost.

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