The Effect of Inflow Mach Number on the Reattachment in Subsonic Flow over a Backward-Facing Step

2016 ◽  
Author(s):  
Dongru Li ◽  
Zia Ghiasi ◽  
Jonathan Komperda ◽  
Farzad Mashayek
Keyword(s):  
Mach Number ◽  
Subsonic Flow ◽  
Backward Facing Step

On Transition From Supersonic to Subsonic Flow at Low Reynolds Numbers in a Tube

1969 ◽  
Vol 36 (2) ◽  
pp. 146-150 ◽  
Author(s):  
R. Y. Chen ◽  
J. C. Williams
Keyword(s):  
Mach Number ◽  
Static Pressure ◽  
Subsonic Flow ◽  
Supersonic Nozzle ◽  
Reynolds Numbers ◽  
Impact Pressure ◽  
Low Reynolds Numbers ◽  
Pressure Distributions ◽  
Low Reynolds ◽  
The Impact

A supersonic low-density gas stream produced in a supersonic nozzle was passed through a circular tube in which the transition from supersonic to subsonic flow took place. Static pressure distributions along the tube (and nozzle) and impact pressure distributions across the tube at several stations were measured to determine the nature of this transition. The impact pressure distributions were used, together with the local static pressure, to infer Mach number and velocity profiles in the tube. When the pressure distributions and center-line Mach number distributions are considered together, one obtains a fairly clear picture of the processes involved in the transition from supersonic to subsonic flow at low Reynolds numbers.

Estimates for critical Mach number under isoperimetric constraints

1995 ◽  
Vol 6 (5) ◽  
pp. 385-398 ◽  
Author(s):  
F. G. Avkhadiev ◽  
A. M. Elizarov ◽  
D. A. Fokin
Keyword(s):  
Mach Number ◽  
Subsonic Flow ◽  
Chaplygin Gas ◽  
Ideal Gas ◽  
Open Problems ◽  
Inverse Boundary ◽  
Critical Mach Number ◽  
Lindelöf Principle ◽  
Isoperimetric Constraints ◽  
Upper Estimate

The problem of maximization of the critical Mach number in a subsonic flow of an ideal gas is considered. The Chaplygin gas approximation and the integral representation of the solution of the inverse boundary-value problem of aerohydrodynamics are used to reduce the problem to a special minimax one. The exact solution of the latter is obtained on the basis of the Lindelöf principle. An upper estimate for the critical Mach number is obtained. The results are generalized for the case of airfoil cascades. Some open problems are described.

The Effect of the Mach Number on a Turbulent Backward-Facing Step Flow

2018 ◽  
Vol 101 (3) ◽  
pp. 653-680 ◽  
Author(s):  
Istvan Bolgar ◽  
Sven Scharnowski ◽  
Christian J. Kähler
Keyword(s):  
Mach Number ◽  
Backward Facing Step ◽  
Step Flow

scholarly journals The onset of compressibility effects for aerofoils in ground effect

2007 ◽  
Vol 111 (1126) ◽  
pp. 797-806 ◽  
Author(s):  
G. Doig ◽  
T. J. Barber ◽  
E. Leonardi ◽  
A. J. Neely
Keyword(s):  
Mach Number ◽  
High Speed ◽  
Subsonic Flow ◽  
Flow Characteristics ◽  
Ground Effect ◽  
Aerodynamic Performance ◽  
Computational Studies ◽  
Pressure Gradients ◽  
Cfd Simulations ◽  
Compressibility Effects

Abstract The influence of flow compressibility on a highly-cambered inverted aerofoil in ground effect is presented, based on two-dimensional computational studies. This type of problem has relevance to open-wheel racing cars, where local regions of high-speed subsonic flow form under favourable pressure gradients, even though the maximum freestream Mach number is typically considerably less than Mach 0·3. An important consideration for CFD users in this field is addressed in this paper: the freestream Mach number at which flow compressibility significantly affects aerodynamic performance. More broadly, for aerodynamicists, the consequences of this are also considered. Comparisons between incompressible and compressible CFD simulations are used to identify important changes to the flow characteristics caused by density changes, highlighting the inappropriateness of incompressible simulations of ground effect flows for freestream Mach numbers as low as 0·15.

Subsonic Flow Over Open Cavities: Part 1 — Analytical Models and Numerical Investigations

2016 ◽  
Author(s):  
Weidong Shao ◽  
Jun Li
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
Shear Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Feedback Loop ◽  
Subsonic Flow ◽  
Free Stream ◽  
Open Cavities ◽  
Free Stream Mach Number

The aeroacoustical oscillation and acoustic field generated by subsonic flow grazing over open cavities has been investigated analytically and numerically. The tone generation mechanism is elucidated with an analytical model based on the coupling between shear layer instabilities and acoustic feedback loop. The near field turbulent flow is obtained using two-dimensional Large Eddy Simulation (LES). A special mesh is used to absorb propagating disturbances and prevent spurious numerical reflections. Comparisons with available experimental data demonstrate good agreement in both the frequency and amplitude of the aeroacoustical oscillation. The physical phenomenon of the noise generated by the feedback loop is discussed. The correlation analysis of primitive variables is also made to clarify the characteristics of wave propagation in space and time. The effects of free-stream Mach number and boundary layer thickness on pressure fluctuations within the cavity and the nature of the noise radiated to the far field are examined in detail. As free-stream Mach number increases velocity fluctuations and mass flux into the cavity increase, but the resonant Strouhal numbers slightly decrease. Both the resonant Strouhal numbers and sound pressure levels decrease with the increase of boundary layer thickness. Results indicate that the instability of the shear layer dominates both the frequency and amplitude of the aeroacoustical oscillation.

DSMC simulation of rarefied gas flow over a 2D backward-facing step in the transitional flow regime: Effect of Mach number and wall temperature

2020 ◽  
pp. 095441002095987
Author(s):  
Deepak Nabapure ◽  
Ram Chandra Murthy K
Keyword(s):  
Mach Number ◽  
Flow Regime ◽  
Surface Properties ◽  
Wall Temperature ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Transitional Flow ◽  
Flow Properties ◽  
Rarefied Gas Flow ◽  
Backward Facing Step

Rarefied gas flow over a backward-facing step (BFS) is often encountered in separating flows prevalent in aerodynamic flows, engine flows, condensers, space vehicles, heat transfer systems, and microflows. Direct Simulation Monte Carlo (DSMC) is a powerful tool to investigate such flows. The purpose of this research is to assess the impact of Mach number and wall temperature on the flow and surface properties in the transitional flow regime. The Mach numbers considered are 5, 10, 25, 30, and the ratio of the temperature of the wall to that of freestream considered are 1, 2, 4, 8. The Reynolds number for the cases studied is 8.6, 17.2, 43, and 51.7, respectively. Typically the flow properties near the wall are found to increase with both Mach number and wall temperature owing to compressibility and viscous dissipation effects. The variation in flow properties is more sensitive to Mach number than the wall temperature. The surface properties are found to decrease with Mach number and increase with wall temperature. Moreover, in the wake of the step, the vortex’s recirculation length is reasonably independent of both free stream Mach number and wall temperature, whereas it decreases with Knudsen number.

scholarly journals Effects of Inflow Mach Number and Step Height on Supersonic Flows over a Backward-Facing Step

2013 ◽  
Vol 5 ◽  
pp. 147916 ◽  
Author(s):  
Haixu Liu ◽  
Bing Wang ◽  
Yincheng Guo ◽  
Huiqiang Zhang ◽  
Wenyi Lin
Keyword(s):  
Mach Number ◽  
Supersonic Flows ◽  
Step Height ◽  
Backward Facing Step

Calculation of Cascade Profiles From the Velocity Distribution

1974 ◽  
Vol 96 (4) ◽  
pp. 407-412 ◽  
Author(s):  
C. Lecomte
Keyword(s):  
Mach Number ◽  
Velocity Distribution ◽  
Subsonic Flow ◽  
A Priori ◽  
External Flow ◽  
Analytical Function ◽  
Graphic Display ◽  
Analytical Functions ◽  
Number Distribution ◽  
Mach Number Distribution

The method using the properties of analytical functions is applied to a plane, steady, inviscid, everywhere subsonic flow. From data fixed a priori concerning the external flow and some details of the profile, the hodograph is obtained as an analytical function whose real part is known on a contour. The set of imposed conditions being in general superabundant, the proposed Mach number distribution is corrected by means of a function whose form is fixed a priori, or rejected altogether. The problem is treated on a graphic display console connected with a computer, which provides also the profile corresponding to the calculated hodograph.

Sign in / Sign up

Export Citation Format

Share Document