Method of combustor cycle airflow adjustment

A method of providing a gas turbine engine, the engine selectively operable in at least a simple configuration and a heat-recuperated configuration, the method comprising the steps of:

• providing a generic gas turbine engine assembly having a combustor;
• determining a first geometry for an airflow path in the gas turbine engine assembly, the first geometry for use when the gas turbine engine is operated in a first one of said engine configurations;
• determining a second geometry for the airflow path of the generic gas turbine engine assembly, the second geometry for use when the gas turbine engine is operated in a second one of said engine configurations different from said first configuration, wherein the second geometry affects a distribution of a total air mass flow in the engine between an air mass flow used for combustion and an air mass flow used for cooling, wherein said distribution results in a flame temperature in a primary combustion zone of the combustor when the gas turbine engine is operated in the second configuration, and wherein said flame temperature is substantially the same as a flame temperature in a primary combustion zone of the combustor when the gas turbine engine is operated in the first configuration with the first geometry, and wherein said first geometry includes a first part and the second geometry includes a second part, and wherein said first part is an combustor impingement cooling skin and said second part is a removable cover adapted to cover a pre-selected number of holes on an impingement cooling skin;
• and
• selecting one of said at least first and second geometries for use in said gas turbine engine assembly based on whether the gas turbine engine is to be operated in said first or second engine configurations.

A method of providing a dry low emission gas turbine engine having a simple air cycle configuration and a heat recuperative configuration, the method comprising the steps of:

• providing a generic gas turbine engine assembly having a combustor;
• selecting a desired combustor flame temperature in a primary zone of the combustor, the desired flame temperature selected to provide a desired NOx emission level from gas turbine engine in operation;
• defining an cooling air flow path around said combustor and a combustion air flow path into said combustor, the cooling air flow path adapted to direct external cooling air around said combustor;
• determining a first fuel-air mixture required to provide the selected flame temperature when the gas turbine engine is operated in said simple air cycle configuration;
• determining a first air flow resistance required in at least one of said air flow paths to provide the first fuel-air mixture when the gas turbine engine is operated in said simple air cycle configuration;
• determining a second fuel-air mixture required to provide the selected flame temperature when the gas turbine engine is operated in said heat-recuperative configuration;
• determining a second air flow resistance required in at least one of said air flow paths to provide the second fuel-air mixture when the gas turbine engine is operated in said heat recuperative configuration;
• providing a first air flow geometry for the cooling air flow path and the combustion air flow path which provides said first air flow resistance and thereby provides said first fuel-air mixture when the gas turbine engine is operated in said simple air cycle configuration;
• providing a second air flow geometry for the cooling air flow path and the combustion air flow path which provides said second air flow resistance and thereby provides said second fuel-air mixture when the gas turbine engine is operated in said heat-recuperative configuration;
• and
• wherein the first air flow geometry and the second air flow geometry each include at least one flow metering orifice for controlling airflow through the cooling air flow path, and wherein the first air flow geometry and second air flow geometry differ by the size of their respective at least one flow metering orifices.

A method of changing a fuel/air mixture ratio provided to a gas turbine combustor, the method comprising the steps of:

• providing a gas turbine engine adapted for use in a simple air cycle configuration, the gas turbine engine having a combustor and an air flow geometry communicating with the combusbor, the air flow geometry adapted to split an air flow between a cooling air flow and a combustion air flow, the geometry permitting a selected flame temperature to be maintained in a primary combustion zone of the combustor;
• modifying the gas turbine engine for use in a heat recuperative configuration, the said modifying step including;
• providing a heat recuperator;
• and
• modifying the air flow geometry to permit the selected flame temperature to be maintained in a primary combustion zone of the combustor and modifying a cooling air flow path flow geometry is modified by removing a part thereof and substituting a different part therefor, said removed part and said substituted part having the same function in the gas turbine engine.

A method of providing a gas turbine engine, the engine selectively operable in at least a simple configuration and a heat-recuperated configuration, the method comprising the steps of:

• providing a generic gas turbine engine assembly having a combustor;
• determining a first geometry for an airflow path in the gas turbine engine assembly, the air flow path including at least a cooling branch and a combustion air branch, the cooling branch adapted to externally cool said combustor, the first geometry for use when the gas turbine engine is operated in a first one of said engine configurations;
• determining a second geometry for the airflow path of the generic gas turbine engine assembly, the second geometry for use when the gas turbine engine is operated in a second one of said engine configurations different from said first configuration;
• and
• adjusting the first and second geometries relative to one another to substantially meet a flow distribution requirement for maintaining a substantially constant primary zone temperature and modifying a cooling airflow path when a configuration of the gas turbine engine is changed between a simple air flow cycle and a heat-recuperated air flow cycle.