Abstract: A machine having a plurality of sub-assemblies, having a geometric computational model is generated for the machine, including the sub-assemblies and one or more module of machine readable code defining how vibration is communicated through said geometric model. First and second instances of the computational model are run to generate outputs of loading throughout the machine geometry as a result of the vibration of the geometric model under a simulated machine operating condition. The first and second instances respectively includes the computational model with and without inclusion of vibration induced by a control system for one or more sub-assembly of the machine. A maximum loading threshold is determined for the machine. A threshold for one or more control parameter in the control system is set based on the contribution of the vibration induced by the control system to the maximum loading threshold.

Abstract: A heat exchanger for a ducted fan gas turbine engine has a low temperature side and plural high temperature sides. The heat exchanger is configured such that heat is extracted from respective engine fluids flowing through the high temperature sides and is received by a portion of a bypass airflow of the engine which, on passing through the fan duct, is diverted through the low temperature side of the heat exchanger thereby cooling the engine fluids.

Abstract: A machine having a plurality of sub-assemblies, having a geometric computational model is generated for the machine, including the sub-assemblies and one or more module of machine readable code defining how vibration is communicated through said geometric model. First and second instances of the computational model are run to generate outputs of loading throughout the machine geometry as a result of the vibration of the geometric model under a simulated machine operating condition. The first and second instances respectively includes the computational model with and without inclusion of vibration induced by a control system for one or more sub-assembly of the machine. A maximum loading threshold is determined for the machine. A threshold for one or more control parameter in the control system is set based on the contribution of the vibration induced by the control system to the maximum loading threshold.

Abstract: A heat exchanger for a ducted fan gas turbine engine has a low temperature side and plural high temperature sides. The heat exchanger is configured such that heat is extracted from respective engine fluids flowing through the high temperature sides and is received by a portion of a bypass airflow of the engine which, on passing through the fan duct, is diverted through the low temperature side of the heat exchanger thereby cooling the engine fluids.