**Author details**

*Hypersonic Vehicles - Past, Present and Future Developments*

*CDB* <sup>=</sup> <sup>2</sup>*π*∫*i*(*CPB*) *ri* sin*dx* \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ *<sup>A</sup>*max

ficient and the base drag coefficient can be seen in **Tables 6** and **7**.

**8. Conclusions**

**Nomenclature**

*t* time

*ρ* density

*B* base

*CD* drag coefficient *CP* pressure coefficient *D* fore-body diameter *d* adapter diameter *F*, *G* flux vectors *H* source vector *L* overall length *M* Mach number *p* static pressure

*RN* radius of sphere *RC* radius of shoulder *x*, *r* coordinate directions

*U* conservative variables in vector form

*α<sup>N</sup>* semi-cone angle of fore-body *α<sup>B</sup>* semi-cone angle of back-shell

*γ* ratio of specific heats *θ* semi-cone angle

*BS* base stagnation point *∞* freestream condition

where *r* and *ψ* are local radius and local inclination angle in the *x*-direction station *i* respectively. *Amax* is the maximum cross-sectional area of the reentry module. **Table 7** shows the base body aerodynamic drag *CDB* for various reentry modules. The present numerical simulation will be validated in future with experimentally measured data in order to assess the error bands between them. The influence of geometrical parameters of the space reentry capsules and freetream Mach number on the base pressure coef-

A main aim of the Chapter is to analyze numerically the base pressure over space reentry vehicles at freestream Mach number range of 1.2–6.0. A numerical algorithm is described to solve compressible laminar axisymmetric Navier-Stokes equations over various reentry capsules. The flowfield over the capsule reveals the effect of the geometrical parameters on the base pressure and base drag coefficients. The CFD methods yield flowfields over space vehicles without the interference of the sting-model attachment in wind tunnel experiments. A low pressure is formed in the base region of the capsule which is characterized by a low-speed recirculation region which can be due to fill-up the growing space. The approaching boundary layer separates at the corner and the free-shear layer is formed in the wake region. The wake flow also shows a vortex attached to the corner with a large recirculation, which depends on spherical nose radius, apex cone angle, back-shell inclination angle and freestream Mach number.

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Subscripts

Rakhab C. Mehta1,2

1 Department of Aeronautical Engineering, Noorul Islam Center for Higher Education, India

2 School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore

\*Address all correspondence to: drrakhab.mehta@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
