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force acting on gas turbine blade....

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Old   August 19, 2007, 00:43
Default force acting on gas turbine blade....
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vvj
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Hi friends...

1. To get the force acting on the turbine blade due to impact of gasses, which pressure i have to take into account?? either static pressure or total pressure??? and why??

2. For 3-d blade multi-stage turbine analysis (again in order to get the force acting on the blade), how many blades i have to consider for geometry modelling?? and why??

3. If i want to capture the shock in case of the turbine blade how far i have to consider the flow field from the blade???

PLZ reply... Thank you... Suggest me a good e-book, for CFD analysis of gas turbines..
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Old   March 3, 2010, 02:04
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Hamid Zoka
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hi,
1-static pressure should be considered in calculations. total pressure is in fact the total energy content of the fluid stream and it has nothing to do with the force exerted on blade surfaces

2-it depends on type of the analysis. in steady state solutions it is enough to model just one blade per each row. but when unsteady calculations is required, the number of blades should be selected such that all rows possess the same pitch. for example if you have 40 stator and 80 rotor, you should model 1 stator and 2 rotor. in cases the blade count ratio is not integer, firstly you should change the number of blades to reach an integer ratio.(refer to unsteady analysis papers)

3-in case you model a subsonic turbine flow and in case shock waves occure in first stage stator, you will clearly see the shock in results it your meshing is fine enough. refer to static pressure and Mach number contours to see their sudden variations through the shcok wave. it is usually recommended to put your inlet/outlet boundries away from leading or trailing edges as much as the thickness of your blade.

best regards
zoka
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