Investigation of Wall Effect on Flow Characteristics in Supersonic Rarefied Gas Flow Past a Confined Square Cylinder Using the DSMC Method

2011 ◽  
Author(s):  
Mohamad M. Joneidipour ◽  
Reza Kamali
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Blockage Ratio ◽  
Parallel Plates ◽  
Square Cylinder ◽  
Rarefied Gas Flow ◽  
Number Distribution ◽  
Mach Number Distribution

In the present study, the effect of wall in supersonic rarefied gas flow past a square cylinder is numerically studied. Therefore, a supersonic rarefied gas flow over a square cylinder is simulated first. Then, the simulations are repeated for a square cylinder confined between two parallel plates. In both cases, the Mach number distribution in the flow field of supersonic rarefied gas over the square cylinder is obtained using the direct simulation Monte Carlo method. Close inspection of contour lines of Mach number over the square cylinder shows that a discontinuity in the flow field occurs across the shock wave at the slip regime while there is no discontinuity at the transition flow regime. In the present paper, the effect of blockage ratio (defined as the distance between two parallel plates divided by the cylinder length) on the Mach number distribution in the flow field of supersonic rarefied gas over the square cylinder is also studied. Meanwhile, the obtained results from both mentioned cases are compared to each other. It is found that the deviation of two sets of data diminishes gradually as the blockage ratio increases.

Design Method for Subsonic and Transonic Cascade With Prescribed Mach Number Distribution

1992 ◽  
Vol 114 (3) ◽  
pp. 553-560 ◽  
Author(s):  
O. Le´onard ◽  
R. A. Van den Braembussche
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Pressure Distribution ◽  
Velocity Component ◽  
Design Method ◽  
Normal Velocity ◽  
Flow Solver ◽  
Number Distribution ◽  
Mach Number Distribution ◽  
Transonic Cascade

A iterative procedure for blade design, using a time marching procedure to solve the unsteady Euler equations in the blade-to-blade plane, is presented. A flow solver, which performs the analysis of the flow field for a given geometry, is transformed into a design method. This is done by replacing the classical slip condition (no normal velocity component) by other boundary conditions, in such a way that the required pressure or Mach number distribution may be imposed directly on the blade. The unknowns are calculated on the blade wall using the so-called compatibility relations. Since the blade shape is not compatible with the required pressure distribution, a nonzero velocity component normal to the blade wall evolves from the new flow calculation. The blade geometry is then modified by resetting the wall parallel to the new flow field, using a transpiration technique, and the procedure is repeated until the calculated pressure distribution has converged to the required one. Examples for both subsonic and transonic flows are presented and show a rapid convergence to the geometry required for the desired Mach number distribution. An important advantage of the present method is the possibility to use the same code for the design and the analysis of a blade.

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.

Design Method for Subsonic and Transonic Cascade With Prescribed Mach Number Distribution

1991 ◽  
Author(s):  
O. Léonard ◽  
R. A. Van Den Braembussche
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Pressure Distribution ◽  
Velocity Component ◽  
Design Method ◽  
Normal Velocity ◽  
Flow Solver ◽  
Number Distribution ◽  
Mach Number Distribution ◽  
Transonic Cascade

An iterative procedure for blade design, using a Time Marching procedure to solve the unsteady Euler equations in the blade-to-blade plane is presented. A flow solver, which performs the analysis of the flow field for a given geometry, is transformed into a design method. This is done by replacing the classical slip condition (no normal velocity component) by other boundary conditions, in such a way that the required pressure or Mach number distribution may be imposed directly on the blade. The unknowns are calculated on the blade wall using the so-called compatibility relations. Since the blade shape is not compatible with the required pressure distribution, a non-zero velocity component normal to the blade wall evolves from the new flow calculation. The blade geometry is then modified by resetting the wall parallel to the new flow field, using a transpiration technique, and the procedure is repeated until the calculated pressure distribution has converged to the required one. Examples for both subsonic and transonic flows are presented and show a rapid convergence to the geometry required for the desired Mach number distribution. An important advantage of the present method is the possibility to use the same code for the design and the analysis of a blade.

scholarly journals A preliminary study on static pressure probe mobile measurement method for flow field in transonic wind tunnel

2021 ◽  
Vol 39 (4) ◽  
pp. 786-793
Author(s):  
Haijun Deng ◽  
Bo Xiong ◽  
Xinfu Luo ◽  
Shaozun Hong ◽  
Qi Liu ◽  
...  
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Flow Field ◽  
Static Pressure ◽  
Wind Tunnel Test ◽  
Flow Characteristics ◽  
Pressure Probe ◽  
Number Distribution ◽  
Mach Number Distribution ◽  
Transonic Wind Tunnel

The axial Mach number distribution of the core flow for model in a transonic wind tunnel is an important index to evaluate the performance of the flow field, which is usually measured by the centerline probe. In order to simulate the incoming flow characteristics without interference, the probe will extend from the support section to the shrinkage section, so the probe usually must has longer inches, more static pressure measuring points and smaller blockage requirements. In order to study the influence of the points of the centerline probe on the uniformity distribution of flow field, a new static pressure probe is designed, which is smaller and shorter than the centerline probe. On the basis of the stability of the flow field, the Mach number distribution of the flow field measured by the static pressure probe which is driven by the moving measuring mechanism. The characteristics of the measured values are studied by wind tunnel test. The results show that: when Ma ≤ 0.95, the overall distribution and value of Mach number obtained by the static pressure probe is basically the same as those obtained by the centerline probe, but some flow field details, which mainly shows that Mach number of the static pressure probe has smaller fluctuation, higher accuracy and better uniformity index.

Rarefied gas flow between two parallel plates

1971 ◽  
Vol 2 (6) ◽  
pp. 65-67 ◽  
Author(s):  
B. I. Porodnov ◽  
P. E. Suetin
Keyword(s):  
Gas Flow ◽  
Rarefied Gas ◽  
Parallel Plates ◽  
Rarefied Gas Flow
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