Aircraft

Abstract

An aircraft comprises a machine body which encloses a turbofan gas turbine engine. The turbofan gas turbine engine includes a heat exchanger module, fan assembly, compressor module, turbine module, and exhaust module. The heat exchanger module communicates with the fan assembly by an inlet duct. The heat exchanger module includes first heat transfer elements that transfer heat energy from a first fluid within the transfer elements to an airflow passing over a surface of the transfer elements before entry of the airflow into a fan assembly inlet. The first fluid contained within transfer elements has a temperature, and the airflow passing over the transfer element surface has a temperature. The turbofan gas turbine engine further includes at least one second heat transfer element, with the or each second heat transfer element transfers heat energy from the first fluid to a second fluid.

1 . An aircraft comprising a machine body, the machine body enclosing a turbofan gas turbine engine, the turbofan gas turbine engine comprising, in axial flow sequence, a heat exchanger module, a fan assembly, a compressor module, a turbine module, and an exhaust module, the heat exchanger module being in fluid communication with the fan assembly by an inlet duct, the heat exchanger module comprising a plurality of first heat transfer elements, the first heat transfer elements being configured for the transfer of heat energy from a first fluid contained within the first heat transfer elements to an airflow passing over a surface of the first heat transfer elements prior to entry of the airflow into an inlet to the fan assembly, the first fluid contained within the first heat transfer elements having a temperature, the airflow passing over the surface of the first heat transfer elements having a temperature, the turbofan gas turbine engine further comprising at least one second heat transfer element, the or each second heat transfer element being configured for the transfer of heat energy from the first fluid to a second fluid,
 wherein, in use, the aircraft can maintain a sustained airspeed, and when the airflow temperature is less than the first fluid temperature, the first fluid passes through the first heat transfer elements, and when the airflow temperature is equal to or greater than the first fluid temperature, the first fluid passes through the second heat transfer elements.   
     
     
         2 . The aircraft as claimed in  claim 1 , wherein the fan assembly comprises a plurality of fan blades defining a fan diameter, and the fan diameter is within the range of 0.3 m to 2.0 m. 
     
     
         3 . The aircraft as claimed in  claim 1 , wherein the heat exchanger module has a fluid path diameter, wherein the fluid path diameter is greater than the fan diameter. 
     
     
         4 . The aircraft as claimed in  claim 1 , wherein the turbofan gas turbine engine further comprises an outer housing, the outer housing enclosing the sequential arrangement of heat exchanger module, fan assembly, compressor module, and turbine module, an annular bypass duct being defined between the outer housing and the sequential arrangement of modules, a bypass ratio being defined as a ratio of a mass air flow rate through the bypass duct to a mass air flow rate through the sequential arrangement of modules, and wherein the bypass ratio is less than 4.0. 
     
     
         5 . The aircraft as claimed in  claim 1 , wherein the fan assembly comprises two or more fan stages, at least one of the fan stages comprising a plurality of fan blades defining the fan diameter. 
     
     
         6 . A method of operating an aircraft comprising a machine body, the machine body enclosing a turbofan gas turbine engine, the gas turbine engine comprising, in axial flow sequence, a heat exchanger module, an inlet duct, a fan assembly, a compressor module, a turbine module, and an exhaust module, and wherein the method comprises the steps of:
 (i) providing the fan assembly, the compressor module, the turbine module, and the exhaust module;   (ii) providing the heat exchanger module with a plurality of first heat transfer elements for transfer of heat from a first fluid contained within the heat transfer elements to an airflow passing over a surface of the heat transfer elements prior to entry of the airflow into the fan assembly, the first fluid having a temperature;   (iii) providing the heat exchanger module with at least one second heat transfer element for the transfer of heat from the first fluid to a second fluid   (iv) positioning the heat exchanger module in fluid communication with the fan assembly by the inlet duct; and   (v) operating the aircraft such that the aircraft maintains a sustained airspeed V and the airflow passing over a surface of the heat transfer elements has a temperature;   (vi) if the airflow temperature is less than the first fluid temperature, directing the first fluid through the first heat transfer elements; and   (vii) if the airflow temperature is equal to or greater than the first fluid temperature, directing the first fluid through the second heat transfer elements.