Temporal characteristics of hypersonic flows over a double wedge with Reynolds number

Laminar hypersonic flows at Mach 7.10 with unit Reynolds numbers of 5.2 × 10 4 , 1.04 × 10 5 , and 4.14 × 10 5 m−1 over a 30°/55° double-wedge configuration were studied to investigate the spatial-temporal characteristics of the flow in a time-accurate manner. Close comparisons were made between previous kinetic and current continuum approaches to test the validity of the continuum assumption, especially considering the presence of large gradients associated with shock-shock and shock-boundary layer interactions, as well as spanwise instabilities. Previous results from direct simulation Monte Carlo, which inherently predicts rarefied effects such as velocity slip and temperature jumps, were found to be in very close agreement with the current work, even for the lowest Reynolds number. The impact of velocity slip and temperature jumps on flow and surface parameters was investigated, and comparisons were made with a no-slip and constant temperature wall model. The temporal and spatial variation of two- and three-dimensional flows were thoroughly investigated using two-dimensional (2D), three-dimensional (3D) periodic sidewall boundary conditions, and a full 3D configuration consistent with existing experimental data. Close comparisons among the 2D and 3D cases were made. The characteristics of 2D periodic oscillations were reported for the moderate Reynolds number case for the first time. The presence of spanwise instabilities, even at a relatively low free stream pressure of about 100 Pa, establishes that the flow field depends on spanwise effects and is fully 3D. High-fidelity numerical schlieren videos captured strong spanwise oscillations for 3D configurations. © 2023 Author(s).12 month embargo; first published 25 October 2023This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Arrythmic markers affected by clozapine treatment in patients with schizophrenia: heart rate variability, late potentials and QT dispersion

Magnetic quadrupole moment of $W$-boson in Kobayashi-Maskawa model, I.B.Khriplovich and M.E. Pospelov, BUDKERINP 93--88 Due to CP-invariance violationa vector particle can acquire T- and P-odd electromagnetic moment, magneticquadrupole one. The W-boson magnetic quadrupole moment is calculated in theKobayashi-Maskawa model. This is the only known CP-odd moment arising in thismodel in two-loop approximation

Shock-shock interactions for a double wedge configuration in different gases

A kinetic, particle method has been used to model laminar shock-shock interactions of hypersonic flow over a 30/55-deg double-wedge configuration studied in the Hypervelocity Expansion Tube (HET) facility. The current study focuses on the investigation of Mach 7 nitrogen, air and argon flows for a stagnation enthalpy of 8.0 MJ/kg, conditions where thermochemical nonequilibrium is present. The simulations are found to reproduce many of the classic features related to Edney Type V strong shock interactions that include the attached, oblique shock formed over the first wedge, the detached bow shock from the second wedge, the strong separation zone, and the separation and reattachment shocks that cause complex features such as the triple point. As reported earlier,1 it was found that a full threedimensional model was required to simulate the heat flux and transient behavior of the nitrogen flow. In contrast, preliminary 2-D results of a reacting air flow case seem to indicate that the size of the separation length and the time required to reach steady state is much less than was found for the 2-D nitrogen flow model and comparison with measured heat fluxes and time-dependent shock profiles for air are in reasonable agreement. Lastly, to understand the effects of the internal modes on the shock structure, argon flow is also studied

Slip effects on the stability of supersonic laminar flat plate boundary layer

Summarization: During the past years joint efforts have been exerted by different researchers for the development of high speed air vehicles as well as hypersonic systems in general, for a wide range of applications. However, such systems involve rarefied gas flows, which appear to be significantly different comparing to flows at the continuum regime; it is this the reason the Navier-Stokes equations fail to simulate such phenomena without further modification. To this end, the enhancement of an in-house academic Computational Fluid Dynamics solver to encounter such simulations is reported in this study. In case of rarefied gas flows and specifically for flows in the slip regime (Knudsen number greater than 0.01) the no-slip condition on solid wall surfaces is no longer valid; hence, velocity slip and temperature jump boundary conditions have to be used instead. (Short description and some difficulties an SBL code can face). The obtained results are compared with those obtained with the parallel open-source code SPARTA, based on the Direct Simulation Monte-Carlo method. According to this last approach, the flow domain is divided into a finite number of computational cells. The required sample macroscopic flow properties are retrieved assuming inter-molecular collisions of the simulated particles inside such cells. An excellent agreement was achieved between the results obtained by SBL and SPARTA. The effect of wall-slip velocity and temperature distributions on the linear stability of supersonic and hypersonic laminar boundary layers developing on a semi-infinite flat plate is investigated for Knudsen numbers, corresponding to flight altitudes of 35km - 65 km and, at first instance, low Reynolds numbers. The steady laminar base flow is obtained using the Direct Simulation Monte Carlo (DSMC) method. Results on the mean-free-path and wall-normal velocity and temperature gradients obtained are used to construct slip-velocity and temperature-jump boundary conditions along the plate surface, following recent updates of the Maxwell / von Smoluchowski theory. These wall boundary conditions, alongside the pertinent streamwise pressure gradient, extracted from the DSMC simulations at the edge of the boundary layer, are used to obtain similar compressible boundary layer profiles, the linear stability characteristics of which are compared with well-known results delivered by Navier-Stokes methods along a range of altitudes, Mach and Reynolds numbers.Παρουσιάστηκε στο: AIAA Science and Technology Forum and Expositio