Abstract: Systems and methods are disclosed for controlling a downhole tool by encoding a tool control signal in a fluid flow and obtaining a temperature response downhole. In an example, a system for controlling a downhole tool includes a signal transmitter, a signal receiver, and a controller. The signal transmitter is uphole of the tool to be controlled (e.g., at surface) and encodes the tool control signal by varying one or more fluid flow parameters of a fluid flow down a well. The signal receiver is positionable in the well in fluid communication with the fluid flow. The signal receiver detects a temperature response in the fluid flow resulting from varying the one or more fluid flow parameters. A controller controls the downhole tool according to the temperature response.

Abstract: Systems and methods are disclosed for controlling a downhole tool by encoding a tool control signal in a fluid flow and obtaining a temperature response downhole. In an example, a system for controlling a downhole tool includes a signal transmitter, a signal receiver, and a controller. The signal transmitter is uphole of the tool to be controlled (e.g., at surface) and encodes the tool control signal by varying one or more fluid flow parameters of a fluid flow down a well. The signal receiver is positionable in the well in fluid communication with the fluid flow. The signal receiver detects a temperature response in the fluid flow resulting from varying the one or more fluid flow parameters. A controller controls the downhole tool according to the temperature response.

Abstract: A gas turbine engine with first and second axial flow compressors and an intercooler therebetween is provided with a bend diffuser and a radial flow diffuser to diffuse the air leaving the downstream end of the first axial flow compressor at a first radial distance from the axis to the upstream end of the intercooler at a second radial distance from the axis. The bend diffuser comprises a first radially outer wall and a second radially inner wall. The first wall is elliptical and the second wall has a profile derived from a relationship between the local area ratio and the path length around the arc such there is rapid diffusion in the bend diffuser without fluid flow separation from the first wall.