In the following two lists of parameters that pertain to the Heat Sink options, either for a component Heat Sink tab or for the Heat Sink itself, the bold face printed variables are calculated, whereas the rest of the variables are user defined. For the Heat Sink component there is one exception. When the external conditions are set to the ambient/flight conditions the values for the temperature, density, kinematic viscosity, and the specific heat are calculated from the Flight / Ambient conditions.
While most parameter units and display formats are controlled by the unit system and Output format options settings, this does apply to the following: k (conductivity), h (per area unit heat transfer coefficient) and H (heat transfer coefficient). These parameters have fixed units and formats, indicated by the 'fixed unit' in the lists below.
Parameters in the Heat Sink tab in a gas turbine component
Multiple heat sinks can be specified in multiple rows of the Heat sinks table. The resulting total heat flux to/from the component is the sum. of the heat fluxes of all rows. Table cells are editable only if they represent user specified model input and are not overridden by User spec Q option. If readonly, the cells have a blue font color.
Heat Sink Component: The heat sink component that is connected to the current component.
| A_ht | The area for heat transfer with the Heat Sink component. |
| A_flow | The area of the gas path. It is necessary for the calculation of the flow velocity and must therefore be the total area available for the total mass flow. |
| D_re | The (hydraulic) diameter; needed for the calculation of the Reynolds number. In case of a compressor this should be the area of one single cascade passage otherwise turbulence will not be well represented. |
| Re | The calculated Reynolds number. |
| k_gas | Thermal conductivity of the gas, fixed unit [W/mK]. |
| Nu_eq | The Nusselt number relation for the specific type of convective heat transfer. |
| Nu | The calculated Nusselt number. |
| d_mat | The characteristic/average distance from the center of the wall material to the gas path (the average heat travel length through the material). |
| k_mat | The thermal conductivity of the material of the current component connected to a Heat Sink component, fixed unit [W/mK]. |
| h_total | The calculated total heat transfer coefficient, fixed unit [W/m2K]. |
| Q_convcond | The calculated heat rate obtained by convection and conduction combined. |
| Eps_rad | The value for the emissivity of the Heat Sink component [-]. |
| T_wall | The calculated wall temperature for radiation calculations. |
| Q_rad | The calculated heat rate due to radiation. |
| Q_total | The summation of Qrad and Qconvcond for the Heat Sink component. A positive value indicates heat transfer into the component, whereas a negative value indicates heat transfer out of the component. |
| User spec Q | This is an option that enables user defined heat rates for the heat sink. |
Parameters of the Heat Sink components
Multiple connections to external/ambient conditions can be specified in multiple rows of the External conditions heat transfer table and the resulting total external heat flux to/from the heat sink component is the sum of the heat fluxes of all rows. Table cells are editable only if they represent user specified model input and are not overridden by User spec Q option or External conditions option. If readonly, the cells have a blue font color.
External conditions: These are the external conditions to which the Heat Sink component transfers heat when this option is enabled:
| Shaft suffix | This option links the Heat Sink to a specific shaft in order for it to have a rotational rate. Typically used when the Heat Sink component represents a rotating Disk. |
| T_ext | The temperature for which the total heat rate to the exterior is calculated, either obtained from the Flight / Ambient conditions or user specified depending on the External conditions option selected. |
| A_ht | The area for heat transfer with ambient. |
| D_re / L_nu | The diameter of the Heat Sink component and/or characteristic length L for the Nusselt number [m]. It is necessary for the calculation of the flow velocity of the airflow over the Heat Sink and calculating the Reynolds number Re for convective heat transfer in case of rotation and/or for calculating the heat transfer coefficient from the Nusselt number. |
| Rho_re | The density of the gas flow over the Heat Sink component, |
| Mu_re | The kinematic viscosity necessary for the calculation of the Reynolds number. |
| Re | The calculated Reynolds number. |
| k_gas | Thermal conductivity of the gas, fixed unit [W/mK]. |
| Cp_gas | Specific Heat of the gas used for the calculation of the Prandtl number. |
| Nu_expression | The Nusselt number relation for the specific type of convective heat transfer. |
| Nu | The calculated Nusselt number. |
| d_mat | The characteristic/average distance from the center of the Heat Sink to the exterior (the average heat travel length through the material). |
| k_mat | The thermal conductivity of the material of the Heat Sink component, fixed unit [W/m K]. |
| h_total | The calculated total heat transfer coefficient, fixed unit [W/m2K]. |
| Q_convcond | The calculated heat rate obtained by convection and conduction combined. |
| Eps_rad | The value for the emissivity of the Heat Sink component, [-]. |
| T_wall | The calculated wall temperature for radiation calculations. |
| Q_rad | The calculated heat rate due to radiation. |
| Q_total | The summation of Qrad and Qconvcond for the Heat Sink component. A positive value indicates heat transfer into the component, whereas a negative value indicates heat transfer out of the component. |
| User spec Q | This is an option that enables user defined heat flux. When checked, the value entered in the Qtotal column will be used and not overridden by calculation from the other column data. |
Multiple connections to other heat sink components can be specified in multiple rows of the Other heat sinks table and the resulting total external heat flux to/from the heat sink component is the sum of the heat fluxes of all rows.
Other Heat sink : Select the other heat sink to which this heat sink is connected.
| H | Heat transfer coefficient H in W/K for calculation Q using Q = H * (Theatsink - Totherheatsink); fixed unit [W/K]. |
| Q | The heat flux to the other Heat Sink component. A positive value indicates heat transfer into the component, whereas a negative value indicates heat transfer out of the component. |
| User spec Q | This is an option that enables user defined heat flux. When checked, the value entered in the Qtotal column will be used and not overridden by calculation from the other column data. |
Heat Sink parameters
