Research On Fuel Flow Measurement And Fuel Supply Law Of The Transient State For Micro Turbine Engine

Two major problems have to be solved in the developing process of micro turbine engine controlsystem. First, the real-time performance and the accuracy of fuel measurement need to be improved aswell as the lack of effective fuel metering means. Second, the unreasonable fuel supply law of thetransient state induces long starting time with some phenomena such as tail gas overheating, largeovershoot of acceleration and deceleration process with long settling time, and high sensitivity of fuelsupply law to external environment. To solve the above problem, the paper carried out the followingresearch.On the area of the fuel metering, a fuel metering controller was developed to meet the need ofresearch on the flow measurement based on turbine flow meter and differential pressure. The demandsof the fuel metering controller were analyzed at first, then an ARM-based fuel metering controllerwith intelligent color terminal as human-computer interface was proposed, and the design methods ofeach software and hardware modules were discussed in detail. The controller can measure and displaythe fuel flow, back pressure, temperature and achieve the real-time communication with the hostcomputer. In addition, it can control the electric pump and meet the requirement of the research on thefuel flow.To carry out research on the real-time performance and the accuracy of fuel measurement basedon turbine flow meter. The problem of the method of frequency measurement, cycle measurement,F/V conversion and frequency multiplication was analyzed through theory and experiments at first,then the dynamic flow measurement based on number of cycles was proposed to obtain dynamic flowsignal with good precision. Experiments had been carried out to test the new measurement methodand results showed that real-time performance and accuracy was improved significantly by using themethod of dynamic flow measurement based on number of cycles, compared to normal measurementmethods, and it can meet the requirement of rig test of micro turbine engine and the development ofmicro turbine engine control system.The fuel supply law of the transient state for micro turbine engine was studied. For the start-upprocess, the fuel supply law was explored through hardware-in-loop simulation and rig test, then thefuel supply law of start-up process was re-designed, and the start-up time is greatly reduced. For theacceleration and deceleration process, the paper first proposed PI with feed forward compensationcontrol algorithm, open-loop and PI control algorithm, open-loop and variable PI control parametersalgorithm in turn which did not achieve good control effect, then the open-loop and variable PI control parameters with delay algorithm was proposed based on the analysis of the engine controlstate mechanism. Experiments had been carried out to test the new method and results showed that theovershoot and settling time is significantly reduced, and it can eliminate the impact of the externalenvironment to the fuel supply law.