Heat retention and distribution system for gas turbine engines

A gas turbine engine comprising:

• a compressor section where air pulled into a flow path of the engine is compressed, the compressor having a compressor outer casing and a plurality of compressor bleed air openings formed through the compressor outer casing;
• a combustor section where fuel is mixed with at least a portion of the compressed air from the compressor section and is combusted to create hot combustion gases;
• a turbine section where the hot combustion gases from the combustor section are expanded to extract energy therefrom, wherein at least a portion of the extracted energy is used to rotate a turbine rotor during a first mode of operation;
• an exhaust manifold downstream from the turbine section, the exhaust manifold comprising a manifold casing for receiving exhaust gases comprising expanded hot combustion gases from the turbine section;
• a plurality of manifold openings formed through the manifold casing;
• a plurality of bleed air ducts extending from each of the compressor bleed air openings to each of the manifold openings for conveying bleed air from the compressor section to the manifold during a third mode of operation prior to the first mode of operation;
• an exhaust return section associated with each of the bleed air ducts, each exhaust return section having an exhaust return section inlet and an exhaust return section outlet located on a respective bleed air duct between respective manifold and compressor bleed air openings;
• and
• the exhaust return sections conveying air that has been warmed during passage of the air through the engine, the warmed air being recirculated from the exhaust manifold to the compressor section through respective bleed air ducts during a second mode of operation comprising rotation of the turbine rotor following a shutdown of the engine ending the first mode of operation.

A gas turbine engine comprising:

• a compressor section where air pulled into a flow path of the engine is compressed, the compressor having a compressor outer casing, a compressor bleed air cavity formed between the outer casing and a compressor vane carrier, and a plurality of compressor bleed air openings formed through the compressor outer casing at the compressor bleed air cavity;
• a combustor section where fuel is mixed with at least a portion of the compressed air from the compressor section and is combusted to create hot combustion gases;
• a turbine section where the hot combustion gases from the combustor section are expanded to extract energy therefrom, wherein at least a portion of the extracted energy is used to rotate a turbine rotor during a first mode of operation;
• an exhaust manifold downstream from the turbine section, the exhaust manifold comprising a manifold casing for receiving exhaust gases comprising expanded hot combustion gases from the turbine section;
• a plurality of manifold openings formed through the manifold casing;
• a plurality of bleed air ducts extending from each of the compressor bleed air openings to each of the manifold openings for conveying bleed air from the compressor section to the manifold during a third mode of operation comprising an engine startup operation immediately preceding the first mode of operation;
• an exhaust return section associated with each of the bleed air ducts, each exhaust return section having an exhaust return section inlet and an exhaust return section outlet located on a respective bleed air duct between respective manifold and compressor bleed air openings;
• the exhaust return sections conveying air that has been warmed during passage of the air through the engine, the warmed air being recirculated from the exhaust manifold to the compressor section through respective bleed air ducts during a second mode of operation comprising rotation of the turbine rotor during a turning gear operation following a shutdown of the engine ending the first mode of operation.