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Oblique shock

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


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Journal ArticleDOI
TL;DR: In this article, a large scale one-dimensional hybrid simulation is performed to investigate the generation mechanism of diffuse superthermal ions at a high Mach number quasi-parallel collisionless shock.
Abstract: [1] A large scale one-dimensional hybrid simulation is performed to investigate the generation mechanism of diffuse superthermal ions at a high Mach number quasi-parallel collisionless shock. The shock exhibits a cyclic behavior and reforms periodically. The generation of the diffuse ions is associated with the reformation of the shock. At the beginning of the reformation cycle, a part of ions are reflected by the shock due to the existence of the cross shock potential. At the same time, an upstream wave is brought back by the upstream plasma and interacts with the shock. The upstream wave begins to steepen as it approaches the shock, and then a new shock front is formed. The reflected ions are trapped between the new and old shock fronts. They are accelerated every time they are reflected by the new shock front until the reformation cycle of the shock is finished and the particles escape from the shock. In this way, diffuse superthermal ions are generated in the quasi-parallel shock, which may be further accelerated to higher energy due to shock diffusive acceleration.

40 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the tone generation mechanism in an underexpanded round jet impinging on a flat plate using compressible large-eddy simulations, and showed that the velocity of flow structures between the nozzle and the plate, and its dependence on the nozzle-to-plate distance, was analyzed using Fourier analysis.
Abstract: Flow structure oscillations and tone generation mechanisms in an underexpanded round jet impinging on a flat plate normally have been investigated using compressible large-eddy simulations. At the exit of a pipe nozzle of diameter D, the jet is characterized by a nozzle pressure ratio of 4.03, an exit Mach number of 1, a fully expanded Mach number of 1.56, and a Reynolds number of 6×104. Four distances between the nozzle and the plate of 2.08D, 2.80D, 3.65D, and 4.66D are considered. Snapshots of vorticity, density, pressure, and mean velocity flowfields are first presented. The latter results compare well with data of the literature. In three cases, in particular, a Mach disk appears to form just upstream from the plate. The convection velocity of flow structures between the nozzle and the plate, and its dependence on the nozzle-to-plate distance, are then examined. The properties of the jet near pressure fields are subsequently described using Fourier analysis. Tones emerge in the spectra at frequencies...

40 citations

Proceedings ArticleDOI
10 Jul 2005
TL;DR: In this article, a data base including a wide range of literature data is established to evaluate the influence of propellant combination and nozzle design on flow separation in rocket nozzles.
Abstract: Cold and hot flow tests were conducted to investigate the flow separation in rocket nozzles. The results are presented. A separatio n data base including a wide range of literature data is established to evaluate the influence of propellant combination and nozzle design on flow separation. As a result a simple separation criteria is suggested. Nomenclature p = pressure cf = friction coefficient Ma = wall Mach number Mades = design Mach number κ = adiabatic exponent θ = deflection angle σ = oblique shock angle u,U = velocity δ = boundary layer thickness δ *

40 citations

Journal ArticleDOI
TL;DR: In this article, a mathematical model for two-dimensional (plane or axis-symmetric) overexpanded jet flow parameters analysis in the vicinity of supersonic nozzle lip is proposed.

40 citations

Journal ArticleDOI
TL;DR: In this article, a small plane mirror is placed just behind the wire so as to be perpendicular to the axis of the optical system and the reflected image of the wire explosion coincides with the disturbance itself when seen through the slit by the camera lens.
Abstract: A simple technique has been found for rendering visible the shock wave formed by an exploding wire after the shock has separated from the luminous contact surface. A small, plane mirror is placed just behind the wire so as to be perpendicular to the axis of the optical system. Thus the reflected image of the wire explosion coincides with the disturbance itself when seen through the slit by the camera lens. Rotating mirror pictures taken under these conditions show very clear outlines of the parabolic shock wave as it propagates ahead of the luminous contact surface. The separation of the shock and contact surface is complete by about one μsec. Beyond this time the shock is clearly nonluminous and ordinarily would not be visible. Comparison of shock trajectories with predictions from the similarity solutions for strong shock waves obtained by S. C. Lin may be interpreted as showing that the shock is receiving additional energy while traversing the early part of its path. After this phase both shock and contact surface accurately obey a parabolic law over intervals of several microseconds.

39 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202369
2022142
2021106
202090
201992
2018102