Oblique shock

About: Oblique shock is a research topic. Over the lifetime, 6551 publications have been published within this topic receiving 119823 citations.

Focusing of Strong Shocks in an Annular Shock Tube

Abstract: Focusing of strong shock waves in a gas-filled thin convergence chamber with various forms of the reflector boundary is investigated experimentally and numerically. The convergence chamber is mounted at the end of the horizontal co-axial shock tube. The construction of the convergence chamber allows the assembly of the outer chamber boundaries of various shapes. Boundaries with three different shapes have been used in the present investigation—a circle, an octagon and a smooth pentagon. The shock tube in the current study was able to produce annular shocks with the initial Mach number in the range M s = 2.3 − 3.6. The influence of the shape of the boundary on the shape and properties of the converging and reflected shock waves in the chamber has then been investigated both experimentally and numerically. It was found that the form of the converging shock is initially governed by the shape of the reflector and the nonlinear interaction between the shape of the shock and velocity of shock propagation. Very close to the center of convergence the shock obtains a square-like form in case of a circular and octagonal reflector boundary. This is believed to stem from the instability of the converging shock front triggered by the disturbances in the flow field. The outgoing, reflected shocks were also observed to be influenced by the shape of the boundary through the flow ahead as created by the converging shocks.

Intensification of shock-induced combustion by electric-discharge-excited oxygen molecules: numerical study

Abstract: Mechanisms of combustion enhancement in a supersonic H2–O2 reactive flow behind an oblique shock wave front are investigated when vibrational and electronic states of O2 molecule are excited by an electric discharge. The analysis is carried out on the base of updated thermally nonequilibrium kinetic model for the H2–O2 mixture combustion. The presence of vibrationally and electronically excited O2 molecules in the discharge-activated oxygen flow allows to intensify the chain mechanism and to shorten significantly the induction zone length at shock-induced combustion. It makes possible, for example, to ignite the atmospheric pressure H2–O2 mixture at the distance shorter than 1 m behind the weak oblique shock wave at a small energy Es = 1.2 × 10–2 J · cm–3 input to O2 molecules. At higher pressure it is needed to put greater specific energy into the gas in order to ignite the mixture at appropriate distances. It is shown that excitation of O2 molecules by electric discharge is much more effective for accel...

Shock-wave/boundary-layer interactions with bleed through rows of holes

Abstract: Computations were performed to investigate three-dimensional, shock-wave/bo undary-layer interactions on a flat plate with bleed through four staggered rows of circular holes that discharge into the same plenum The focus of the computations was to examine how bleed through rows of holes affect bleed rate and the pressure and Mach number distributions The effects of the following parameters on the flow were investigated: 1) with and without shock-wave impingement on the boundary layer and 2) spacings between bleed holes in the streamwise and spanwise directions Results show that just two rows of bleed holes arranged in a staggered fashion placed upstream of the incident shock are adequate in blocking the shock-induced adverse pressure gradient from propagating further upstream Results also show that the spacings between the centers of holes can exceed the hole diameter not just in the streamwise direction, but also in the spanwise direction, and still be able to control shock-induced flow separation This study is based on the ensemble-averaged, "full compressible" Navier-Stokes (N-S) equations closed by the Baldwin-Lomax algebraic turbulence model Solutions to the ensemble-averaged N-S equations were obtained by an implicit, partially split, two-factored algorithm with flux-vector splitting in the streamwise direction on a chimera overlapping grid

Calculation of transonic internal flows using an efficient high-resolution upwind scheme

Abstract: A new efficient upwind scheme based on the concept of convective upwind and split pressure is developed. The upwinding of the convective term and the pressure split are consistent with their characteristic directions. The scheme has low diffusion to resolve accurately wall boundary layers and is able to capture crisp shock waves and exact contact discontinuities. The accuracy of the scheme is compared with other popularly used schemes including the Roe scheme, the Liou's latest advection upstream splitting method scheme (AUSM + ), the Van Leer scheme, and the Van Leer-Hanel scheme. The new scheme is tested for the one-dimensional Sod shock tube problem, one-dimensional slowly moving contact surface, supersonic flat plate laminar boundary layer, a transonic nozzle with oblique shock waves and reflections that do not align with the mesh lines, and a transonic inlet diffuser with shock wave/turbulent boundary-layer interaction