A single nozzle guide vane (NGV) cooling flow can be defined in the Cooling tab sheet of the turbine. NGV cooling flow is assumed to represent the flow cooling the 1st stage stator vanes of the turbine (in case a multi-stage turbine is simulated by the GSP turbine component).

NGV cooling flow is entirely mixed with the turbine flow BEFORE turbine work is extracted during the expansion process. The NGV cooling flow therefore always fully contributes to the extracted turbine work, where for the other bleed flows (which are mixed just before turbine exit) the contribution to the delivered work is dependent on the Press. Frac. parameter.

The following data must be specified in the single available row:

•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.