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Contemporary high speed diesel engines require a compromise regarding the size of fuel nozzle orifices which should be small enough to assure a good fuel atomization at low engine speed, and large enough to provide the engine with high fuel dose at maximum power. Calculations were made to predict the dynamic response of a closed diesel injector within its unstable operation range. The pressure in the seat chamber under the needle was established as the key factor to simulate the injector's behaviour. It was measured at different flow conditions and used in calculations. After applying an optimization method, it was possible to predict how the design parameters of an injector should be changed in order to obtain the best dimentional configuration which improves the fuel atomization at low engine speed.

A new family of low cost electronic fuel control units is being proposed for small gas turbine engines of remotely piloted vehicles and auxiliary power units. It has a modular design incorporating an electronically actuated metering valve which can be matched with various types of differential pressure valves controlling the pressure drop across the metering valve. Four different configurations are proposed: metering valve only, metering valve with diaphragm type differential pressure valve, metering valve with bypass valve and double valve configuration, the latter with a back-up capability. These configurations can satisfy various demands from gas turbine engine producers. Some components of automotive fuel injection system could be used to reduce the cost of these units as well as components from the DP-F2 fuel control which has been in production for a long time. This adds to the confidence of the reliability and durability of this new design.

Optimization of diesel injection system using computer aided design involves complex high speed, high pressure hydraulic transient process calculation. To find the fuel discharge characteristic from injector, the fuel pumping process is first computed based on the design parameters of the injection pump. Then, knowing the forward propagating pressure wave, the dynamic response of the injector is calculated resulting in the fuel discharge process. However, if the forward pressure wave could be precisely measured instead of being calculated, and then substituted into the computer program the total calculation procedure would be substantially reduced. In this paper, a computer controlled data acquisition system with high sampling rate was used to record the fuel pumping process in a specially made long pipe to avoid distortion by the reflected pressure wave. This method is convenient, quite accurate and can save the time of computer simulation.

The potential benefits of digital electronic controls, including increased flexibility and lower cost, have not yet been fully applied to the small gas turbine engines of remotely piloted vehicles. For these applications, the need for low cost is a strong factor in design. To address this situation, a new, simple and inexpensive electronically controlled metering system for small gas turbine engines is proposed. The system incorporates a diaphragm type valve keeping a constant differential pressure across a stepper motor actuated metering valve. To optimize the design, mathematical models were created for computer simulation. Experimental tests performed on a prototype showed that it can adequately meet the fuel schedules of small gas turbines. The simulation models were validated against the test results and were used in design optimization.