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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 paper, detailed pitot, static, and wall pressure measurements have been obtained for multiple transonic shock-wave/turbulent boundary-layer interactions in a circular duct at a freestream Mach number of 1.49, a unit Reynolds number of 4.90xl0/m, and a blockage of 5.15%.
Abstract: An experimental study is described in which detailed pitot, static, and wall pressure measurements have been obtained for multiple transonic shock-wave/turbulent boundary-layer interactions in a circular duct at a freestream Mach number of 1.49, a unit Reynolds number of 4.90xl0/m, and a blockage of 5.15%. The details of the flowfield show the formation of a series of normal shock waves with successively decreasing strength and decreasing distance between the successive shock waves up to the point where a terminal shock occurs. A one-dimensional flow model based on the boundary-layer displacement thickness is postulated to explain the formation of the series of normal shock waves. A comparison with the results from our previous study involving a single shock interaction suggests that the effect of increased blockage is to promote multiple shock interactions and produce a lower pressure recovery, a less retarded boundary-layer flow, and an increase in the overall length of the interaction.

66 citations

Journal ArticleDOI
TL;DR: In this paper, a relativistic, electromagnetic, and particle simulation code with full ion and electron dynamics was proposed to study the electron motion in an oblique shock wave by means of a one-dimensional, relativism, electromagnetic and particle simulations code.
Abstract: Electron motion in an oblique shock wave is studied by means of a one-dimensional, relativistic, electromagnetic, particle simulation code with full ion and electron dynamics. It is found that an oblique shock can produce electrons with ultrarelativistic energies; Lorentz factors with γ≳100 have been observed in our simulations. The physical mechanisms for the reflection and acceleration are discussed, and the maximum energy is estimated. If the electron reflection occurs near the end of a large-amplitude pulse, those particles will then be trapped in the pulse and gain a great deal of energy. The theory predicts that the electron energies can become especially high at certain propagation angles. This is verified by the simulations.

66 citations

Proceedings ArticleDOI
21 Aug 2006
TL;DR: In this paper, first-order piston theory is used to calculate the forces, moments, and stability derivatives for longitudinal motion of a hypersonic vehicle in a two-dimensional inviscid flow.
Abstract: For high Mach number flows, M ≥ 4, piston theory has been used to calculate the pressures on the surfaces of a vehicle. In a two-dimensional inviscid flow, a perpendicular column of fluid stays intact as it passes over a solid surface. Thus, the pressure at the surface can be calculated assuming the surface were a piston moving into a column of fluid. In this work, first-order piston theory is used to calculate the forces, moments, and stability derivatives for longitudinal motion of a hypersonic vehicle. Piston theory predicts a relationship between the local pressure on a surface and the normal component of fluid velocity produced by the surface’s motion. The advantage of piston theory over other techniques, such as Prandtl-Meyer flow, oblique shock, or Newtonian impact theory, is that unsteady aerodynamic effects can be included in the model. The unsteady effects, considered in this work, include perturbations in the linear velocities and angular rates, due to rigid body motion. This provides a more accurate model that agrees more closely with models derived using computational fluid dynamics or those derived by solving Euler equations. Additionally, piston theory yields an analytical model for the longitudinal motion of the vehicle, thus allowing design trade studies to be performed while still providing insight into the physics of the problem.

66 citations

Journal ArticleDOI
TL;DR: The de Hoffman-Teller frame of the reference (HTF) was used in this article to measure the electrostatic potential jump across a fast collisionless plasma shock, which was shown to be about 2-6 times smaller than the expected potential jump in the normal incidence frame.
Abstract: Within the magnetic ramp of fast collisionless plasma shocks observed with spacecraft instruments and simulated numerically, the magnetic field undergoes an excursion out of the plane of coplanarity. This rotation is consistently in the direction such that the electrostatic potential jump across the shock, as measured in the de Hoffman-Teller frame of the reference (HTF), is about 2-6 times smaller than the electrostatic potential jump measured in the normal incidence frame. The preferred direction is consistent with a basic whistler mode transition between the upstream and downstream orientations. The potential jump in the HTF is considerably smaller than the change in bulk flow energy across the shock, confirming the recent suggestion that magnetic forces contribute importantly to the slowing of the plasma in that frame. A further consequence is that suprathermal particles leaking back into the upstream region across the shock do not gain much energy from the cross-shock electric field.

66 citations

Proceedings ArticleDOI
05 Jan 2015
TL;DR: In this paper, the detonation structure, pressure gain, and thrust production in a rotating detonation engine (RDE) were studied using a combination of experimental and numerical approaches.
Abstract: The detonation structure, pressure gain, and thrust production in a rotating detonation engine (RDE) are studied using a combination of experimental and numerical approaches. High frequency time-dependent and low frequency time-averaged static pressure and thrust measurements are acquired for a range of operating conditions and geometry configurations. Acoustic coupling between the detonation channel and air plenum is important for low air mass flow rates and large air injection slots based on analyses of the pressure measurements in the time and frequency domains. The static pressure increases across the air inlet by up to approximately 15% when utilizing a large air injection slot. The pressure increase across the air inlet demonstrates encouraging progress towards realizing pressure gain combustion in RDEs with corresponding challenges associated with isolating the inlet plenums. The time-dependent pressure measurements acquired using a semi-infinite tube arrangement and time-averaged pressure measurements acquired using a capillary tube attenuated arrangement agree to within 30% depending upon location. Quantification of the similarities and differences between the two techniques represents important progress towards acquiring quantitative time-dependent pressure measurements in the challenging environment presented by RDEs. Twodimensional simulations of the RDE capture the essential features of the flow field such as the detonation wave height and angle, trailing edge oblique shock wave, shear layer between the freshly and previously detonated products, and deflagration between the fuel fill region and expansion region containing detonated products. The presence of air purging from the plenum to the channel behind the detonation wave is suggested by the comparison of measured and simulated channel pressure distributions. The pressure, thrust, and wave speed measurements provide benchmark data that are useful for evaluating low and high fidelity simulations of RDEs and improving fundamental understanding of the critical design parameters that influence RDE operation and performance.

66 citations


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