Gas turbine engine with adaptive turbine clearance control system and method

A gas turbine engine, comprising:

• a fan section;
• a fan bypass air path extending axially along an axis and extending radially between an inner radial structure and an outer radial structure;
• a fan exit guide vane extending radially within the fan bypass air path between the inner radial structure and the outer radial structure;
• a compressor section;
• a combustion section;
• a turbine section including a high pressure turbine section, a low pressure turbine section and a turbine case clearance control segment, the turbine case clearance control segment including a first turbine case clearance control segment and a second turbine case clearance control segment, the first turbine clearance control segment disposed radially outside of a high pressure rotor stage within the high pressure turbine section, and the second turbine case clearance control segment disposed radially outside of a low pressure rotor stage within the low pressure turbine section;
• a turbine active clearance control system that includes an air inlet device, a first valve, a heat exchanger, and a second valve, the air inlet device is engaged with the inner radial structure and is configured to extract fan bypass air from the fan bypass air path;
• wherein the first valve is in fluid communication with the fan bypass air path to receive a fan bypass air flow from the fan bypass air path, and is configured to provide the fan bypass air flow to the heat exchanger, or to the second valve, or to both;
• wherein the heat exchanger is configured to permit heat transfer within the heat exchanger between the fan bypass air flow provided to the heat exchanger and a compressor bleed flow from the compressor section provided to the heat exchanger to produce a flow of conditioned air;
• wherein the second valve is configured to receive the fan bypass air flow from the first valve and to receive the flow of conditioned air from the heat exchanger, the second valve in fluid communication with the first turbine clearance control segment and the second turbine case clearance control segment;
• and
• wherein the turbine active clearance control system is configured to operate in a heating mode, and in the heating mode the second valve is configured to provide the flow of conditioned air, or a combined air flow that includes the flow of conditioned air and the fan bypass air flow, to the turbine case clearance control segment.

A method of actively controlling rotor tip clearance in a gas turbine engine, the gas turbine engine including a fan section, a fan bypass air path, a compressor section, a combustion section, a high pressure turbine section having a high pressure rotor stage, a low pressure turbine section having a low pressure rotor stage, a first turbine case clearance control segment disposed radially outside of the high pressure rotor stage and a second turbine case clearance control segment disposed radially outside of the low pressure rotor stage, the method comprising:

• providing a turbine active clearance control system that includes a first valve, a heat exchanger, and a second valve;
• using the first valve to receive a fan bypass air flow from the fan bypass air path, and to provide the fan bypass air flow to the heat exchanger, or to the second valve, or to both;
• wherein the heat exchanger is configured to permit heat transfer within the heat exchanger between the fan bypass air flow provided to the heat exchanger and a compressor bleed flow extracted from the compressor section and provided to the heat exchanger to produce a flow of conditioned air;
• using the second valve to receive the fan bypass air flow from the first valve and to receive the flow of conditioned air from the heat exchanger;
• and
• operating the turbine active clearance control system between a heating mode and a cooling mode;
• wherein the heating mode includes controlling the second valve to provide the flow of conditioned air, or a combined air flow that includes the flow of conditioned air and the fan bypass air flow, to the first turbine case clearance control segment and the second turbine case clearance control segment;
• and
• wherein the cooling mode includes controlling the first valve to vary relative amounts of the fan bypass air flow provided to the heat exchanger and the fan bypass air flow provided to the second valve, and controlling the second valve to vary relative amounts of the flow of conditioned air and the fan bypass air flow provided to the first turbine case clearance control segment and the second turbine case clearance control segment.