Supersonic Flow Of Viscous Gas Research Articles

Duality of the Stream Pattern of Supersonic Viscous Gas Flow past a Blunt-Fin Junction: the Effect of a Low Sweep Angle

Duality of the Stream Pattern of Supersonic Viscous Gas Flow past a Blunt-Fin Junction: the Effect of a Low Sweep Angle

Duality of the stream pattern of supersonic viscous gas flow past a blunt-fin junction: effect of a low sweep angle

Results of numerical solution of the problem of supersonic flow past a symmetric blunt fin mounted on a plate with a developing boundary layer are presented. Generally, the case considered corresponds to the flow configuration used in the experimental and computational study by Tutty et al. (2013), in which the laminar air flow with the freestream Mach number of 6.7 is considered. Previously, the authors have shown (2020) that for these conditions two stable solutions corresponding to metastable flow states with different configurations of the vortex structure and the pattern of local heat transfer are predicted. In present paper, the influence of a low sweep angle of a blunt leading edge on the vortex structure in the separation region, local heat transfer, and the possibility of obtaining a dual solution are investigated. The bifurcation diagrams showing for two solutions the main horseshoe vortex center location and the length of separation region versus the skew angle are presented.

Duality of the Vortex Structure Arising in a Supersonic Viscous Gas Flow Past a Plate and a Blunt-Fin Body Junction

The results of a numerical solution of the problem of supersonic flow past an elongate blunt-fin body mounted on a plate with developing laminar boundary layer are presented. The calculations cover flow cases with the freestream Mach number equal to 6.7 and two different Reynolds numbers: Re = 1.25 × 104 and 1.56 × 104. The structure of the horseshoe vortices arising in the body leading-edge region is analyzed. It has been revealed that, for both Re values, ​​there are two stable solutions that correspond to different metastable states of the flow. The solutions differ in the number of vortices forming in the separation region and its length. In the smaller Reynolds number case, both solutions are steady-state, whereas in case of a larger Re value one of them remains steady-state, and the other one becomes quasi-periodic.

Асимптотическое решение задачи Коши для уравнения первого порядка с возмущенным фредгольмовым оператором

We consider the Cauchy problem for a first-order differentialequation in a Banach space. The equation contains a small parameter in the highest derivative and a Fredholm operator perturbed by an operator addition on the right-hand side. Systems with small parameter in the highest derivative describe the motion of a viscous flow, the behavior of thin and flexible plates and shells, the process of a supersonic viscous gas flow around a blunt body, etc. The presence of a boundary layer phenomenon is revealed; in this case, even a small additive has a strong influence on the behavior of the solution. Asymptotic expansion of the solution in powers of small parameter is constructed by means of the Vasil’yeva- Vishik-Lyusternik method. Asymptotic property of the expansion is proved. To construct the regular part of the expansion, the equation decomposition method is used. It is consisted in a step-by-step transition to similar problems of decreasing dimensions.

Numerical simulation of the unsteady propagation of combustion in a duct with a supersonic viscous gas flow

The effect of the type of mathematical model on the results of numerical simulations of combustion in a flat model combustion chamber with a supersonic flow is considered. The process of formation of a flow with combustion in a chamber includes the propagation of the combustion wave along the chamber and the emergence of a pseudoshock structure. The results of nonstationary calculations by the explicit scheme using (1) the no-slip boundary condition at the chamber walls and the local time stepping procedure, (2) law-of-the-wall and the local time stepping procedure, and (3) law-of-the-wall and the fractional time stepping procedure are compared. Arguments in favor of the applicability of the latter approach to solving this class of problems are presented. The physical results obtained are analyzed.

Supersonic Flow of Viscous Gas in a Flat Channel at High Values of the Reynolds Number

Based on numerical analysis of two-dimensional Reynolds equations using the differential model of turbulence, the structure of flow field and aerodynamic characteristics of a flat channel with variable cross section at the inlet Mach number of four is investigated in the range of Reynolds numbers Re = 105–107. According to the calculation results, the interaction between a shock and a laminar boundary layer results in the emergence of a closed separation zone. During interaction with a turbulent boundary layer, two flow schemes are possible, depending on the intensity of incident shock, namely, without and with separation. The extrapolation of calculation data to nonviscous flow (limiting transition Re → ∞) shows that the classical scheme of regular reflection of the shock from a flat surface corresponds to interaction without separation. Corresponding to interaction with separation is the flow scheme with formation of a small closed separation zone in which a subsonic circulation flow takes place.

Numerical analysis of supersonic viscous gas flow past axisymmetric nonpointed bodies

Supersonic viscous homogeneous gas flow past axisymmetric smooth nonpointed bodies is analyzed numerically for widely varying Mach and Reynolds numbers and flow geometry. The initial equations of a viscous shock layer are solved by the stabilization method. The effect of the determining parameters on the flow character and the heat transfer distribution along the surface is analyzed. The accuracy and domain of applicability of several approximate approaches to the solution of the problem are estimated.

Numerical investigation of supersonic viscous gas flow over long blunt cones with allowance for equilibrium physicochemical effects

Supersonic axisymmetric viscous heat-conducting gas flow over long spherically biunted cones is considered over a broad range of Reynolds numbers on the basis of the complete system of viscous shock layer equations. An economical numerical method based on global iterations is used to solve the viscous shock layer equations. The general influence of the second-approximation effects of boundary layer theory and the influence of equilibrium physicochemical processes on the heat loads are determined for bodies with a large aspect ratio.

Supersonic viscous gas flow around a cooled spherical blunt body

Supersonic viscous gas flow around a cooled spherical blunt body

Shock-layer thickness for supersonic viscous gas flow past blunt bodies

Shock-layer thickness for supersonic viscous gas flow past blunt bodies

Asymptotic study of viscous compressible gas flow past a blunt body

Supersonic viscous gas flow past a blunt body is examined. A method is proposed which permits constructing the asymptotic expansion of any order in the small parameter e, which characterizes the viscosity and thermal conductivity coefficients. The asymptotic solution is constructed, including terras of zero, first, and second orders of e. Acomparison is made with results of other authors who have studied various particular aspects of the subject problem using the method of inner and outer expansions [1–3].

Numerical calculation of flow in the region of spherical blunting for small Reynolds numbers

The problem of supersonic viscous gas flow past two-dimensional bodies (the circular cylinder in particular) was examined in [1, 2]. In what follows we present some results for the case of axisymmetric blunt bodies, obtained with the use of the same method. The calculations were made to determine the aerodynamic characteristics of the flow for small Reynolds numbers; it was assumed that the equations of continuum mechanics remain valid. In the case of sufficiently small Reynolds numbers, when the applicability conditions of this method may be violated, it is natural to consider the numerical results obtained as being formal. There are approximate approaches to the study of viscous flow in the vicinity of a blunt-nose ([3–5] and others); in those cases when this is possible, a comparison is made with some of these theoretical results, and also with experimental data.