Numerical simulation of hypervelocity projectiles in detonable gases

Abstract

A numerical scheme for calculating hypersonic flows involving shock-induced combustion is discussed. The analysis is limited to inviscid flow and includes chemical nonequilibrium and real-gas effects. Two types of flows are considered. First, the hypersonic, exothermic blunt-body flow problem is examined for mixtures of Hi/Oi and Hi/air, and the numerical results are compared with experimental results. Second, a hypervelocity mass launcher concept known as the "ram accelerator" is investigated in the velocity range of 5-7 km/s. Temperature contours and the distribution of various physical quantities along the ram accelerator projectile surface and tube wall are presented for a 14-deg nose projectile and for a gas mixture of 2Hi + Oi + 5He.

An Efficient Multigrid Algorithm for Compressible Reactive Flows

“…4, it can be seen that the agreement between the computation and experiment is quite good. This computation also agrees favorably with the simulation of Yungster et al [45] who limited the cell Damköhler number so that the heat release was spread out among two to three cells. Because of the point implicit treatment of the chemical model, no such limitation is necessary using the current formulation.…”

“…Oscillations in temperature and pressure may lead to inaccurate production and destruction of radicals. The Total Variation Diminishing (TVD) approach has been taken by several investigators [25,26,39,43,44,45,46] to try to accurately capture shock waves and reaction fronts. Yee and Shinn [40] investigated several aspects of semi-implicit and fully implicit shock-capturing methods for reacting flow.…”

“…Numerous investigators have used the point implicit approach for both steady state [8,44,45] and unsteady simulations [26,39]. Wilson and Sussman [39] combined the point implicit treatment with a formulation of the species conservation equations in logarithmic form.…”

Wave angle for oblique detonation waves

“…2 can be found in the literature as far back as 1963 (Gross 1963). Many recent examples of this type of figure are also found in the literature, since it is basic to ram accelerators (Hertzberg et al 1991;Yungster et al 1991), oblique detonation wave engines (Menees et al 1992;Ostrander et al 1987), and detonation wave theory in Correspondence to: G. Emanuel general Powers and Stewart 1992;Powers and Gonthier 1992;Buckmaster and Lee 1990;Lasseigne and Hussaini 1993). Buckmaster and Lee (1990) point out that a weak underdriven wave violates the second law of thermodynamics.…”

Oblique Detonations: Theory and Propulsion Applications

“…These experiments have directly motivated further, primarily numerical studies: (Brackett and Bogdanoff, 1989), , (Yungster, et al, 1991), (Yungster and Bruckner, 1992), (Bogdanoff, 1992), Yungster (1992), and (Pepper and Brueckner, 1993). In particular, the numerical calculations of Yungster and Bruckner, 1992, predict that a ram accelerator can achieve a steady-state velocity such that a combustion-induced thrust force balances drag forces.…”