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-   -   Unable to Capture Shock in Transonic Flow (http://www.cfd-online.com/Forums/cd-adapco/56965-unable-capture-shock-transonic-flow.html)

Tim January 23, 2009 02:27

Unable to Capture Shock in Transonic Flow
 
Hi,

I'm modeling transonic flow across a turbine blade.The conditions are blade inlet angle=58.9deg, Mach=0.845, turbulence model is k-w.

I am able to observe Mach numbers of greater than 1 across my blade..However, I am not able to see a shock across the blade?

Any inputs?

Thanks

Koblax January 23, 2009 15:51

Re: Unable to Capture Shock in Transonic Flow
 
do you use ideal gas?

January 23, 2009 21:05

Re: Unable to Capture Shock in Transonic Flow-----
 
Yes, I am using Ideal Gas...should i use constant density gas instead??

Tim January 26, 2009 08:01

Re: Unable to Capture Shock in Transonic Flow
 
Hi there,

I used constant density gas...It gives me an improved model of the Cp distribution of the blade...However, it is unable to track the shock..

Timothy

anon January 26, 2009 19:58

Re: Unable to Capture Shock in Transonic Flow
 
You shouldn't be using constant density for transonic flow. If you say you can see M>1, then somewhere you should also have M<1, that's where your shockwave is. Try making the mesh denser to capture the shock.

Tim January 28, 2009 00:37

Re: Unable to Capture Shock in Transonic Flow
 
Hi anon,

Thanks for your reply, tried refining the mesh til the absolute size of the volumetric control is 0.03mm but i still could not detect the shock or drop in Mach in my model.

The chord length is around 60mm fyi...Tried inviscid flow but it still shows the same pressure distribution...Any suggestions ?? Novice in this area.

Tim


Tim January 29, 2009 07:05

Re: Unable to Capture Shock in Transonic Flow
 
Hi just to give the full picture...Here are the parameters of my model:

3D, Stationary, Ideal Gas, Coupled FLow, COupled energy, steady,turbulent, RANS, K-E model, turbulence intensity 0.1, turbulence viscosity ratio 500, velocity [272.1,442,0] m/s, temp 987.2K, pressure (gauge) 147675Pa. Using stag inlet for inflow, pressure outlet for outflow, and wall(periodic boundary) for upper and lower part of the model.

Thanks

Tim


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