Supersonic flow past a sphere
2 Attachment(s)
Here is the scheme of cfd problem. A sphere (0.17m diameter) is streamlined by air.
Attachment 12258 The outer boundary is a freestream with params: mach number = 9.52; static pressure = 101325 Pa; temperature = 288K. The inner boundary is a no-slip wall. I'd like to obtain a pressure distribution over the sphere surface (pressure vs angle). Is it possible to estimate aerodynamic heating of the sphere surface? Attachment 12257 If there were any analytic formulas it would suit me fine. I've tried to simulate it in cfd program without any success. I didn't manage to make it converged. |
2 Attachment(s)
Quote:
For example, my in-house density based CFD solver is easily coped with it. (see attachments with 2D-axisymmetric p and T fields) http://www.cfd-online.com/Forums/att...1&d=1333375000 http://www.cfd-online.com/Forums/att...1&d=1333375051 I think that your problem is in the wrong boundary conditions. Instead of setting the conditions for the freestream flow around the outer edge you need to specify the conditions of the freestream flow at the inlet and zero gradient for outlet PS: Which CFD code you are used for simulation ? PPS: As for the air temperature behind the shock wave in the given conditions by you exceeds 4000K, I would recommend to use the model for the properties of air, which takes into account the dependence of the thermodynamic properties on temperature and the dissociation |
Quote:
|
Quote:
It is blended (CD-LxF) scheme with locally adapted blending factor |
Thank you Sergey.
Quote:
Quote:
|
2 Attachment(s)
Quote:
BC - No Inlet and top side - freestream BC Outlet - zero gradient in X direction Wall of sphere - no-sleep BC (wall assumed adiabatic) bottom side - axisymmetric BC (it is 2D-axisymmetric formulation) Quote:
Distribution in x direction of P and T on sphere wall attached http://www.cfd-online.com/Forums/att...1&d=1333804819 http://www.cfd-online.com/Forums/att...1&d=1333804836 |
Quote:
One more question. How long does it take the surface of sphere to get so hot (~4000K)? What's the order of magnitude? |
Quote:
One more question. How long does it take the surface of sphere to get so hot (~4000K)? What's the order of magnitude? |
Quote:
|
Quote:
The solution of unsteady heat conduction is a separate task. At first we can approve assumption of having a uniform distribution of heat in the area (an infinitely large thermal conductivity of the sphere) Warm-up time can be estimated on the basis of the scope of information about the specific heat of material and empirical relations for heat transfer coefficient for sphere (Nusselt number). Or directly simulate coupled unsteady task of heat transfer between gas and solid body if your software allow this Of course, in this case the adiabatic wall condition is not applicable |
Quote:
|
All times are GMT -4. The time now is 21:12. |