Figure 4 - uploaded by Gaurav Kunal Jaiswal
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Pressure contours for plain blunt-nosed body, bodies with aero-spikes and BBN bodies at 0 and 8 degrees angles of attack.
Source publication
The vehicles flying at hypersonic are intentionally designed to have a blunt nose which provides better thermal management. However, this advantage does not stand alone but comes with associated wave drag penalty due to bow-shock at the nose. To minimize the drag, a forward facing conical spike at the nose, a breathing blunt nose have been investig...
Contexts in source publication
Context 1
... the flow past the model, the pressure contours are obtained in the plane of symmetry of the model. The pressure contours for plain blunt-nosed body and for the bodies with three different spike configurations; conical spike, flat faced aero-disk and hemispherical aero disk, used in the present study are shown in Figures 4(a)-(d). The formation of bow-shock, causing high pressure in the forebody zone can be visualized in all the cases. ...
Context 2
... separation of boundary layer forms a free shear layer that separates the inner re- circulation region and thus attains highest reduction in the pressure values in the proximity of blunt nose as compared to other two spikes' configurations. The effect of introducing simple and modified BBN configurations at 0 and 8 degrees angles of attack is shown in Figure 4(e)-(f). It is observed that the strength of detached shock is attenuated by BBN as compared to the plain blunt-nosed body which, in turn, reduces the pressure in the forebody zone. ...
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Citations
Drag is a major problem at hypersonic speeds. A breathing blunt nose is a technique which can be used to minimize this drag for blunt bodies travelling at such speeds. A stagnation region is formed downstream of a detached bow shock just ahead of the body. This results in a large increase in the positive pressure at the blunt nose and causes drag. A low pressure region at the base also contributes to the overall drag of the body. This technique aims at reducing both wave and base drag by introducing a hole at the center of the blunt nose and passively manipulating the flow. This paper aims to study the effects of a breathing blunt nose and the drag reduction due to it. Numerical simulation based methods (ANSYS Fluent CFD) are used to observe the changes occurring in the coefficients of aerodynamic forces and at varying flow conditions from Mach 5 to Mach 8. A Normal Blunt Nose (NBN) and Breathing Blunt Nose (BBN) with hole diameters 5mm, 10mm and 15mm are simulated at angles of attack 0⁰, 5°, 10° and 15°. The 2D results obtained are compared visually by looking at the pressure and velocity contours and numerically in the form of coefficients of lift and drag. It is inferred that the stagnation region in the front and the under pressure region in the rear of the body weaken for the BBN when compared to the NBN. A reduction in drag and an increment in lift is observed with an increase in nose hole diameter for almost all Mach numbers and orientations. Certain trends are observed and plotted with drag reduction being the primary focus and the possible reasons for these trends have been discussed.
