The concept of the bulk temperature is that adiabatic mixing of the fluid from a given cross section of the duct will result in some equilibrium temperature that accurately reflects the average temperature of the moving fluid.
假设你的流道长为L。如果你只是想知道从x=0到x=L的流体的平均bulk temperature的话,你就用(enthalpy_in+enthalpy_out)/2反查一个温度就行了。