Some Performance Characteristics of a Gas Tribune Engine with Enhanced Torque Amplification at Part Speed

A novel gas turbine engine, the Co-Turbo-shaft Engine, featuring a co-rotating compressor casing geared to the output shaft, has been proposed as a powerplant for heavy equipment applications because of its steep torque-speed curve. To evaluate the performance of this engine, it was modelled on a hybrid computer.

The οutput power and torque at fixed gas generator speed and reducing output speed was of main interest. It was found that the stall torque was about 3 times the design torque, while peak power was achieved at about 60% of design output shaft speed, and was up to 1157% of design power. A surprising result for a fixed geometry engine was that this increase in power was achieved with almost constant turbine inlet temperature.

A simplified analysis showed that turbine inlet temperature is controlled by three factors, two tending to increase the temperature and one decreasing it, as shaft speed drops.