The Effects of Cross Section Variations on the Pressure Distribution around a Long Axisymmetric Body

چکیده مقاله

In this study, the effects of presence of belts are experimentally studied for supersonic flow
field around a long axisymmetric body. Also, the longitudinal and circumferential pressure
coefficients along with the boundary layer profile are investigated for angles of attack of -2 to
6 degrees. To this end, two conical-cylindrical belts were installed at middle and end parts of
ogival cylinder model. To ensure the turbulent flow around the model, trip strip was used to
cause artificial disturbances and the acquired results are compared with the acquired results
from the model without a trip strip. To study the effects of the cross section variations on the
pressure distribution and on the boundary layer profiles, three different belts with various
leading edge angles were installed at different locations along the cylindrical portion of the
model. These belts caused major variations in both the surface pressure distributions and the
boundary layer profiles. Passing of flow over the belt leads to sudden increases and decreases
in pressure coefficient distribution on the belt that is due to sudden cross section variations and
consequent development of reverse flow or flow separation regions and production of vortices
along the flow path. Also, the presence of belt causes the development of oblique shock wave
on the model, which in turn reduces the Mach number downstream of the belt. Studying the
circumferential pressure distribution reveals that the presence of belt leads to more asymmetric
flow downstream the model which is intensified as the angle of attack increases. Since the
experimental results are limited, the numerical simulation of the problem is also carried out to
complete the acquired results from the experimental tests, the acquired results of which show
good agreement with the experimental results.

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