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-   -   how to d othis blade passage analysis ?pls he (http://www.cfd-online.com/Forums/cd-adapco/55093-how-d-othis-blade-passage-analysis-pls-he.html)

kaen January 18, 2006 10:58

how to d othis blade passage analysis ?pls he
 
Hi i am doing flow analysis of single blade passage .I am using folowing strategies but nothing works.pls help me in this regard.Total Pressure at inlet is 2.83 bar,Total temp =923 K inlet flow velocity=125 m/sec.Out totoal pr=1.12 bar.,total temp=760 K,Velocity=125 m/sec.rotational speed of passge=60,000 rpm (6280 rad/sec).mas flow =0.596 kg/sec.What i am doing is first giving less rotational speed and when it converges increases speed in next run by taking initial file of prevouis. (1)when i am giving inlet pressure and outlet poressure wit h steady condition and speed as 100 rad/sec.the flo w is cinserved.but real mass flow at inlet and outlet is not achived. it is in terms of thousands insread actual valkue 0.596 kg/sec. (2) when i am giving unsteady solutuion directly without doing steady solution then it says divergence detected in AMG solver.I am reducing underrelaxation parametrs but notjing works.temeprature limit also crosses 5000. so pls tell me which boundary conditon shouls be applied.also shoud i first do steady analysis and then transient analysis.or directly unsteady analysis. thanking u all.


Tinku January 23, 2006 11:41

Re: how to d othis blade passage analysis ?pls he
 
Hello Kaen,

You know the outlet tot. pressure. So you find out the approximate static pressure at Outlet by considering some 90 or 95 % loss. And in my opinion you use the following BCs: At Inlet: Total Pressure and Total Temperature At Outlet: Static Pressure and also give the Rotational speed for the balde. Please try above BCs. If this also fails, we will try some other BC.

ALl the best.

Tinku January 24, 2006 06:41

Re: how to d othis blade passage analysis ?pls he
 
In my earlier response, i forgot to add one more point.....at outlet you should also give the mass flowrate along with Static Pressure


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