A fuel system for a gas turbine engine includes a main fuel pump generating a main fuel flow into a main fuel passage and a secondary pump generating a secondary fuel flow into a secondary flow passage. A first control valve is disposed in a passage between the main fuel passage and the secondary flow passage. The first control valve selectively directs an excess portion of the main fuel flow to the secondary flow passage to provide at least a portion of the secondary fuel flow.

A fuel system for a gas turbine engine includes a main fuel pump generating a main fuel flow into a main fuel passage and a secondary pump generating a secondary fuel flow into a secondary flow passage. A first control valve is disposed in a passage between the main fuel passage and the secondary flow passage. The first control valve selectively directs an excess portion of the main fuel flow to the secondary flow passage to provide at least a portion of the secondary fuel flow.

A heat exchange system for an aircraft engine includes a heat exchanger, a main conduit directing fuel to a combustion chamber of the aircraft engine, and a pump connected to the main conduit. A return conduit receives excess fuel outputted by the pump and exceeding a fuel requirement of the combustion chamber. The return conduit, which is connected to a fuel conduit of the heat exchanger, has an inlet connected to the main conduit downstream of the pump and an outlet connected to the main conduit upstream of the pump. An actuator has an inlet connected to the main conduit downstream of the pump and an outlet connected to the main conduit upstream of the pump while bypassing the heat exchanger, wherein a pressure differential between the actuator inlet and the actuator outlet remains substantially unchanged with variations of a fuel flow through the heat exchanger.

A hydraulic motor-driven fuel boost pump includes redundant safeguards against overspeeding the impellers. A flow limiter limits the amount of hydraulic fluid that can be supplied to the hydraulic motor, thereby limiting the torque that can be applied to the impellers. A control valve also transitions between a non-restrictive operating state and a restrictive operating state. In the restrictive operating state the control valve regulates the displacement of the swash plate when in the non-restrictive operating state. The control valve does not counter the bias of the swash plate control spring when in the restrictive operating state.

A pumping system includes a first variable displacement pump having a first inlet and a first outlet. The first outlet is fluidically connected to a system outlet. A first actuator is mechanically coupled to a first displacement mechanism of the first variable displacement pump A second variable displacement pump includes a second inlet and a second outlet. The second outlet is fluidically connected to the system outlet. The pumping system also includes a second actuator mechanically coupled to a second displacement mechanism of the second variable displacement pump. An electrohydraulic servo valve is hydraulically connected to the first and second actuators. An electronic engine controller is in communication with the electrohydraulic servo valve and is configured to send electrical current to the electrohydraulic servo valve to drive the first actuator and the second actuator.

A pump system for a gas turbine engine including a first pump connected to a fluid flow demand line for delivering fluid to a fluid flow demand and a second pump connected, in parallel to the first pump, to the fluid flow demand line and supplementing fluid to the actuation or burner system based on the fluid flow demand. A pressure regulating valve (PRV) is fluidly connected to the flow demand line for bypassing flow to a pump inlet pressure of the first pump and second pump, and controlling a modulated pressure flow signal to a bypass valve, wherein the bypass valve is in fluid communication with the second pump and the PRV for receiving modulated pressure from the PRV and regulating delivery of fluid from the second pump to a bypass flow line.

A pump system for a gas turbine engine including a first pump connected to a fluid flow demand line for delivering fluid to a fluid flow demand and a second pump connected, in parallel to the first pump, to the fluid flow demand line and supplementing fluid to the actuation or burner system based on the fluid flow demand. A pressure regulating valve (PRV) is fluidly connected to the flow demand line for bypassing flow to a pump inlet pressure of the first pump and second pump, and controlling a modulated pressure flow signal to a bypass valve, wherein the bypass valve is in fluid communication with the second pump and the PRV for receiving modulated pressure from the PRV and regulating delivery of fluid from the second pump to a bypass flow line.

A multi-stage fluid pump system can include a first stage configured to provide a first pressure and a second stage configured to provide a second pressure. The pump system can be configured to prevent output of the second stage in a first stage mode such that only the first pressure is output from the first stage and second stage and to allow output of the second stage in a multi-stage mode such that there is a combined pressure output from the first stage and the second stage.

A multi-stage fluid pump system can include a first stage configured to provide a first pressure and a second stage configured to provide a second pressure. The pump system can be configured to prevent output of the second stage in a first stage mode such that only the first pressure is output from the first stage and second stage and to allow output of the second stage in a multi-stage mode such that there is a combined pressure output from the first stage and the second stage.

In a one embodiment, a gas turbine system that includes a first pump that supplies distillate fuel to a combustor. A second pump that supplies fuel oil to the combustor. A fuel selection unit that controls a first flow of distillate fuel and a second flow of fuel oil to the combustor. A controller that receives feedback from a sensor and in response to the feedback from the sensor controls the fuel selection unit to start the gas turbine system on the fuel oil.