Nusselt number variation over a ribbed surface

avi031 · March 8, 2011, 15:48

Hi,
I am Avinash. I am working on "Heat transfer analysis in a turbine blade cooling passage of trapezoidal crossection"
Boundary conditions:
Inlet-Mass flow
Outlet-Pressure outlet
Two opposite surfaces of the passage are given constant heat flux and are of the same value. The surfaces have 45 degree ribs to enhance heat transfer coefficients.
Problem: I need to obtain the variation of nusselt number over the heated surfaces..therefore a central line was drawn over each of the surface and the surface nusselt number was plotted.....but unfortunately i am not getting realistic values of the nusselt number......lot of difference between the expt and cfd values. Convergence criteria was met. Realizable k-epsilon model was used. Can somebody pls provide suggestions in getting the suitable values of the nusselt number???

Regards
Avinash

foamcfd · March 9, 2011, 12:57

What is the value of y+. For your kind of analysis it should be less than 1. Also try using k-omega SST instead of K-epsilon.

Regards,

yogesh

avi031 · March 10, 2011, 13:09

@yogesh

my y+ value is 3.7

...........i will use the sst k-omega model and see if i can get accurate values..your reply has been helpful....thank you very much

March 8, 2011, 15:48	Nusselt number variation over a ribbed surface	#1
avi031 New Member Avinash Join Date: Jan 2011 Posts: 18 Rep Power: 15	Hi, I am Avinash. I am working on "Heat transfer analysis in a turbine blade cooling passage of trapezoidal crossection" Boundary conditions: Inlet-Mass flow Outlet-Pressure outlet Two opposite surfaces of the passage are given constant heat flux and are of the same value. The surfaces have 45 degree ribs to enhance heat transfer coefficients. Problem: I need to obtain the variation of nusselt number over the heated surfaces..therefore a central line was drawn over each of the surface and the surface nusselt number was plotted.....but unfortunately i am not getting realistic values of the nusselt number......lot of difference between the expt and cfd values. Convergence criteria was met. Realizable k-epsilon model was used. Can somebody pls provide suggestions in getting the suitable values of the nusselt number??? Regards Avinash

March 10, 2011, 13:09		#3
avi031 New Member Avinash Join Date: Jan 2011 Posts: 18 Rep Power: 15	@yogesh my y+ value is 3.7...........i will use the sst k-omega model and see if i can get accurate values..your reply has been helpful....thank you very much

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March 9, 2011, 12:57		#2
foamcfd New Member Yogesh Patil Join Date: Nov 2009 Posts: 20 Rep Power: 17	What is the value of y+. For your kind of analysis it should be less than 1. Also try using k-omega SST instead of K-epsilon. Regards, yogesh