# Stanton Number and Arbitrary Surface Temperature

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 March 8, 2006, 21:36 Stanton Number and Arbitrary Surface Temperature #1 Boris Vaisman Guest   Posts: n/a Hello everyone, -- problem -- Please advise, how would you calculate the Stanton Number (St) on flat plate with an arbitrary surface temperature? Per se, if air inlet temperature (T_in) is 1000 and the plate surface (T_w) goes from 500 to 1000. What is the proper way to calculate St? -- details -- In general St = q_w(x)/(rho*c_p*u*dT), where: - rho, c_p, and u are evaluated at free stream values - q_w(x) is evaluated at the wall - dT is either a reference value or T_in-T_w(x) My dilemma is a follows. (1) If dT is a constant reference value, St would change sign, as T_w changes from T_wT_in. This seems to contradict all definitions of the Reynolds Analogy Factor (R). Consider von Karman or Spalding and Chi, R is always positive and constant or almost constant. (2) On the other hand, if dT(x)= T_in-T_w(x), there will be a point where q_w(x) changes sign (for the above scenario), but dT(x) has not changed sign yet (for a short distance). This will cause St to explode. This is also problematic. What is the proper way to calculate St? ---- Thank you very much for your time and help. Boris Vaisman

 March 9, 2006, 04:43 Re: Stanton Number and Arbitrary Surface Temperatu #2 versi Guest   Posts: n/a In my case, St number is St = q_w(x)/(rho*u*dH), where dH= H_in-H_w, H is total enthaphy=h + q^2/2. Unless singificantly heating from interior, dH always >0.