Overpressure

About: Overpressure is a research topic. Over the lifetime, 3236 publications have been published within this topic receiving 34648 citations.

Supersonic Inlet Shaping for Dramatic Reductions in Drag and Sonic Boom Strength

Abstract: An alternate approach has been identified for defining supersonic inlet compression surface geometry, the use of which increases the design latitude for lofting the inlet cowling region while permitting control over other key inlet design variables. Through this approach, a novel inlet design space is analytically shown to significantly improve supersonic aircraft performance and reduce sonic boom overpressure compared to high-speed inlets designed using traditional methods and constraints. Installed specific fuel consumption improvements of up to 11 percent and sonic boom overpressure reductions of 16 percent were observed for a podded axisymmetric external compression inlet designed for Mach 1.8 cruise. A theoretical discussion and physical description of the alternate inlet design concept is provided along with a summary of the analysis methodology used to judge the concept’s merit against conventional configurations. Inlet performance metrics, presented as a function of key design variables, are compared; and CFD solutions of the compression and diffusion flow environment are included. Drag characteristics at off-design Mach number are also presented. An extended range, low sonic boom vehicle concept is used as an aircraft study platform for which installed CFD-based drag and sonic boom comparisons are made.

Numerical study of blast characteristics from detonation of homogeneous explosives

Abstract: A new robust numerical methodology is used to investigate the propagation of blast waves from homogeneous explosives. The gas-phase governing equations are solved using a hybrid solver that combines a higher-order shock capturing scheme with a low-dissipation central scheme. Explosives of interest include Nitromethane, Trinitrotoluene, and High-Melting Explosive. The shock overpressure and total impulse are estimated at different radial locations and compared for the different explosives. An empirical scaling correlation is presented for the shock overpressure, incident positive phase pressure impulse, and total impulse. The role of hydrodynamic instabilities to the blast effects of explosives is also investigated in three dimensions, and significant mixing between the detonation products and air is observed. This mixing results in afterburn, which is found to augment the impulse characteristics of explosives. Furthermore, the impulse characteristics are also observed to be three-dimensional in the region of the mixing layer. This paper highlights that while some blast features can be successfully predicted from simple one-dimensional studies, the growth of hydrodynamic instabilities and the impulsive loading of homogeneous explosives require robust three-dimensional investigation.