Oblique shock

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

Upstream particle events close to the bow shock and 200 RE upstream: ISEE-1 and ISEE-3 observations

Abstract: Two energetic particle events (28 keV - 145 keV) upstream of the earth's bow shock have been investigated with two identical experiments of the Max-Planck-Institut/University of Maryland on ISEE-1 and ISEE-3. Close to the bow shock the particle distribution is more or less isotropic and indicates strong scattering of these particles in the upstream wave field. At ISEE-3 the particles move essentially scatter-free from the general bow shock direction. The temporal evolution of the particle bursts is discussed in terms of the interplanetary magnetic field topology and the scattering conditions.

Reduction of Fluctuating Pressure Loads in Shock/Boundary-Layer Interactions Using Vortex Generators

Abstract: Fluctuating wall pressure measurements have been made in a separated shock wave/turbulent boundary-layer interaction produced by an unswept compression corner in a Mach 5 flow Wheeler doublet vortex generators were placed upstream of the corner to study their effect on the fluctuating pressure loads within the interaction The vortex generators produce significant three dimensionality in an otherwise two-dimensional interaction They reduce the upstream influence and the length of the region of separation shock motion by 60 % and 64 %, respectively, and they decrease the maximum wall pressure rms near separation by 23% and shift the fluctuations to higher frequencies The maximum fraction of energy in the resonant frequency band of typical skin panels (ie, 100-500 Hz) is decreased by 11% On the corner face, where the maximum loads occur, the maximum wall pressure rms is reduced by 10%, and the maximum fraction of energy in the 100-500 Hz band is reduced by 35% These changes are due to a fuller boundary-layer profile, a weaker separation shock, increased boundary-layer turbulence causing increased separation shock jitter, and a shorter region of shock motion

Large-Eddy Simulation of an Oblique Shock Impinging on a Turbulent Boundary Layer

Abstract: Large-eddy simulation (LES) of an oblique shock impinging on a supersonic turbulent boundary layer is carried out with a high-order compact differencing scheme using localized artificial diffusivity (LAD) for shock capturing. Flow conditions attempt to match those of the tomographic particle image velocimetry (PIV) experiments conducted at the Delft University of Technology (M∞ = 2.05 and φ = 8°). However, due to computational cost, the Reynolds number is taken to be Reδ = 20,000 (1/30 th of the experimental Reynolds number), and an attempt is made to geometrically match the interaction parameters. Inflow conditions are generated by an improved recycling/rescaling method to eliminate the non-physical “tones” associated with standard recycling/rescaling. The numerical scheme is first validated by simulating a two-dimensional laminar shock wave / boundary layer interaction (SWBLI). Next, a three-dimensional simulation with progressive mesh refinement is conducted to investigate flow physics and establish confidence in the ability of the computational method to accurately and efficiently simulate complex supersonic flow phenomena. Mean and fluctuating profiles of velocity, pressure, and skin friction provide good indication of grid convergence between the two highest levels of refinement. Instantaneous data fields are analyzed, and observations are made regarding “flapping” motion caused by boundary layer turbulence and spanwise variation in shock location. Additionally, the range of spatial and temporal scales captured by the present work is quantified by analyzing spanwise wavenumber and frequency spectra at various locations in the flow. Through analysis of the frequency spectra of the wall pressure signal, low-frequency motion of the separation bubble with a time scale ~O(100δ/u∞) is observed and described. Through direct comparison, we additionally observe that standard recycling/rescaling inflow conditions may result in different low-frequency behavior.

Annular Truncated Plug Nozzle Flowfield and Base Pressure Characteristics

Abstract: The flowfield and base pressure characteristics of an internal-external-expansion, truncated plug nozzle are described over the pressure ratio range from "open" wake to "closed" wake conditions. The effect of plug length on these characteristics, including the process of wake "closure" is also presented. An existing method for calculating the flowfield and base pressure, for closed wake operation, is modified to include the internal shock wave generated near the shroud exit. The supersonic portion of the flow is calculated using rotational axisymmetric method of characteristics. The technique of Hartree is employed so that the downstream characteristic point locations can be chosen to fit the developing flowfield. An overexpansion technique is used to detect the internal shock wave in the vicinity of the shroud exit so that its effect on the plug base pressure could be determined. Good agreement between the analytical results and experimental data is obtained for closed wake operations.