Prediction of the compressibility effect on airfoil stall at low Mach numbers

1994 ◽  
Keyword(s):  
Compressibility Effect ◽  
Mach Numbers

A numerical study of turbulent supersonic isothermal-wall channel flow

1995 ◽  
Vol 305 ◽  
pp. 159-183 ◽  
Author(s):  
G. N. Coleman ◽  
J. Kim ◽  
R. D. Moser
Keyword(s):  
Channel Flow ◽  
Numerical Study ◽  
Plane Channel ◽  
Reynolds Numbers ◽  
Mean Values ◽  
Compressibility Effect ◽  
Total Temperature ◽  
Isothermal Wall ◽  
Mach Numbers ◽  
Centreline Velocity

A study of compressible supersonic turbulent flow in a plane channel with isothermal walls has been performed using direct numerical simulation. Mach numbers, based on the bulk velocity and sound speed at the walls, of 1.5 and 3 are considered; Reynolds numbers, defined in terms of the centreline velocity and channel half-width, are of the order of 3000. Because of the relatively low Reynolds number, all of the relevant scales of motion can be captured, and no subgrid-scale or turbulence model is needed. The isothermal boundary conditions give rise to a flow that is strongly influenced by wall-normal gradients of mean density and temperature. These gradients are found to cause an enhanced streamwise coherence of the near-wall streaks, but not to seriously invalidate Morkovin's hypothesis : the magnitude of fluctuations of total temperature and especially pressure are much less than their mean values, and consequently the dominant compressibility effect is that due to mean property variations. The Van Driest transformation is found to be very successful at both Mach numbers, and when properly scaled, statistics are found to agree well with data from incompressible channel flow results.

scholarly journals The compressible turbulent shear layer: an experimental study

1988 ◽  
Vol 197 ◽  
pp. 453-477 ◽  
Author(s):  
Dimitri Papamoschou ◽  
Anatol Roshko
Keyword(s):  
Growth Rate ◽  
Mach Number ◽  
Shear Layer ◽  
Large Scale ◽  
Turbulent Shear ◽  
Plane Shear ◽  
Compressibility Effect ◽  
Pressure Profiles ◽  
Mach Numbers ◽  
Convective Mach Number

The growth rate and turbulent structure of the compressible, plane shear layer are investigated experimentally in a novel facility. In this facility, it is possible to flow similar or dissimilar gases of different densities and to select different Mach numbers for each stream. Ten combinations of gases and Mach numbers are studied in which the free-stream Mach numbers range from 0.2 to 4. Schlieren photography of 20-ns exposure time reveals very low spreading rates and large-scale structures. The growth of the turbulent region is defined by means of Pitot-pressure profiles measured at several streamwise locations. A compressibility-effect parameter is defined that correlates and unifies the experimental results. It is the Mach number in a coordinate system convecting with the velocity of the dominant waves and structures of the shear layer, called here the convective Mach number. It happens to have nearly the same value for each stream. In the current experiments, it ranges from 0 to 1.9. The correlations of the growth rate with convective Mach number fall approximately onto one curve when the growth rate is normalized by its incompressible value at the same velocity and density ratios. The normalized growth rate, which is unity for incompressible flow, decreases rapidly with increasing convective Mach number, reaching an asymptotic vaue of about 0.2 for supersonic convective Mach numbers.

MULTIDIMENSIONAL SIMULATIONS AND TEST FIRES OF A HYDROGEN-FUELED RAMJET WITH AN ANNULAR DETONATIVE COMBUSTOR AT APPROACHING AIR FLOW OF MACH 2 AND 1.5

2020 ◽  
Author(s):  
V. S. IVANOV ◽  
◽  
V. S. AKSENOV ◽  
S. M. FROLOV ◽  
P. A. GUSEV ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
High Speed ◽  
Constant Pressure ◽  
Air Flow ◽  
Thermodynamic Cycle ◽  
Aerial Vehicles ◽  
Mach Numbers

Modern high-speed unmanned aerial vehicles are powered with small-size turbojets or ramjets. Existing ramjets operating on the thermodynamic cycle with de§agrative combustion of fuel at constant pressure are efficient at flight Mach numbers M ranging from about 2 to 6.

scholarly journals Estimation of Mach numbers in supersonic jets using schlieren images

2021 ◽  
Author(s):  
Mohammed Faheem ◽  
Aqib Khan ◽  
Rakesh Kumar ◽  
Sher Afghan Khan ◽  
Waqar Asrar ◽  
...  
Keyword(s):  
Supersonic Jets ◽  
Mach Numbers ◽  
Schlieren Images

scholarly journals Investigation of gasdynamic parameters of a supersonic flow near a body at various Mach numbers

2020 ◽  
Vol 1697 ◽  
pp. 012240
Author(s):  
A V Shevchenko ◽  
A S Yuriev ◽  
S A Poniaev ◽  
T A Zhitnikov ◽  
E B Panfilov ◽  
...  
Keyword(s):  
Supersonic Flow ◽  
Mach Numbers

scholarly journals A Low Mach Number IMEX Flux Splitting for the Level Set Ghost Fluid Method

2021 ◽  
Author(s):  
Jonas Zeifang ◽  
Andrea Beck
Keyword(s):  
Level Set ◽  
Phase Interface ◽  
Time Discretization ◽  
Spectral Element ◽  
Computational Time ◽  
Minor Role ◽  
Ghost Fluid Method ◽  
Specific Level ◽  
Flux Splitting ◽  
Mach Numbers

AbstractConsidering droplet phenomena at low Mach numbers, large differences in the magnitude of the occurring characteristic waves are presented. As acoustic phenomena often play a minor role in such applications, classical explicit schemes which resolve these waves suffer from a very restrictive timestep restriction. In this work, a novel scheme based on a specific level set ghost fluid method and an implicit-explicit (IMEX) flux splitting is proposed to overcome this timestep restriction. A fully implicit narrow band around the sharp phase interface is combined with a splitting of the convective and acoustic phenomena away from the interface. In this part of the domain, the IMEX Runge-Kutta time discretization and the high order discontinuous Galerkin spectral element method are applied to achieve high accuracies in the bulk phases. It is shown that for low Mach numbers a significant gain in computational time can be achieved compared to a fully explicit method. Applications to typical droplet dynamic phenomena validate the proposed method and illustrate its capabilities.

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