Turbine cooling flows can be defined to accurately model the thermodynamic effects of turbine cooling. In the Cooling tab sheet an unlimited number of cooling flows can be entered, each row representing data of a separate cooling flow. The following data must be specified in the subsequent columns:

•Nr

The cooling flow number to identify the cooling flow with a unique number in the model. Note that these numbers do not correspond with compressor bleed flow numbers.

•Bleed flow nr

The compressor bleed flow number providing the cooling flow. This number must represent an existing compressor bleed flow, defined in a compressor component.

•Frac. for cool.

The fraction of the compressor bleed flow used for this turbine cooling flow.

•Frac. Eff. T.flow

The fraction of the cooling flow that contributes to the turbine effective flow. A larger or smaller part of the flow can be added to the flow obtained from the flow - pressure ratio relation in the map. A fraction of 1 means all cooling flow requires a proportional share of the cross flow area, at the cost of the turbine entry flow (e.g. the main flow exiting the combustor) so that for the same pressure ratio the entry flow is smaller. This would be the case if all cooling flow enters the turbine at the entry. If all cooling flow would enter at the exit, the fraction should be set to 0. Usually this fraction value is set between 0 and 1 and used to accurately fine-tune the model to known engine data.

•Press. Frac.

This fraction represents the extent to which the cooling flow contributes to the expansion process providing mechanical power in the turbine. At 0, no expansion power is provided. At value 1, the cooling flow entirely expands with a pressure ratio equal to the turbine pressure ratio, starting with the (compressor) bleed flow temperature. Usually this fraction value is set between 0 and 1 and used to accurately fine-tune the model to known engine data.

•Exit radius [m]

This is a radius for calculation of the effect of the increase in kinetic energy of the cooling flow due to the increase in velocity of the flow passages with increasing distance (radius) from the rotating shaft centerline. The kinetic energy is added to the cooling flow enthalpy and subtracted from the turbine shaft power. The radius is specified in meters and usually is set equal to the average distance of the blades to the shaft centerline. This value can be used to accurately fine-tune the model to known engine data.

Turbine cooling flow output parameters are identified by the turbine local cooling flow number (e.g. Wcl3_6 is mass flow rate of cooling flow nr. 3 in turbine component nr. 6).