Gas path components for gases with potentially high temperatures allow specification of heat transfer data to allow simulation of heat flow to or from the component material during transients. During an gas turbine engine acceleration for example, the turbine material is heated up to the new steady state temperature level and since this heat is taken from the gas, transient performance may be affected significantly. The reverse case happens during deceleration when the material heats up the relatively cool gas. Heat soakage heat transfer coefficient is a function of and gas path conditions and user specified data, to be specified in the 'Heat soak' tab sheets of gas path components data entry windows. Note that also the Heat sink will cause a heat soakage effect (on top of the steady-state heat transfer) if the heat sink mass is specified >0.
The material temperature dynamic response is a 1st order response following the equation:
with heat transfer coefficient Uht calculated as follows:
FC is the film coefficient, calculated from
with FCdes as a user specified film coefficient in the design point. cp,des and Wdes are the gas specific heat and mass flow calculated for DP and cp and W the OD calculated values.
The average material temperature Tm is calculated by integrating:
Initial value for Tm is the steady state gas temperature. Since heat flow is assumed to be proportional to the difference between gas and material temperature the material temperature Tm follows the average gas temperature Tg with a first order lag. The time constant is determined by
Heat soakage effects
