Researcn On Tne Oil Supply System Of A Certain Type Of Aeroengine Nozzle Test-bed

Nozzle flow test beds are the key equipments used to detect the flow performance of the aeroengine lubricating oil nozzles. Test bench mainly includes measuring system, temperature control system, filtration system, vacuum system, oil supply system, electric control system, pneumatic system, etc. Among them, the oil supply system is one of the core system of test bed, its function is to provide lubricating oil with a certain accuracy, temperature and pressure for nozzles. The stability and reliability of the oil supply system performance directly affects the reliability of nozzle flow measurement results.In nozzle flow rate measurement, there are two main prerequisites:assure ubricating oil temperature within 65℃～75℃ and the nozzle inlet pressure in the range of 250±1 kpa.Due to the low pressure of oil supply system, it is more sensitivity to the stress fluctuation.Because oil supply system flow pulsation, pipeline vibration, oil spills, and high sensitivity to the pressure fluctuation, there are great difficulties about constant pressure control of oil supply system. So the design of the oil supply system become one of the key problems of test bench.In view of the constant pressure control problem of the oil supply system, this paper designed a kind of intelligent pressure regulating oil supply system. In the system, oil supply is carried out by a gear pumpl, the highest pressure is setted by a proportional relief valve, the flow pulsation is absorbed by an accumulator, the nozzle inlet pressure is regulated by a servo valve, a pressure sensor is setted at the nozzle inlet, combined with which the PLC (programmable logic controller) makes up pressure closed loop control.Both the dynamic mathematical model of the oil supply system and the constant pressure control model of the fuzzy self-tuning PID are established. Through MATLAB/Simulink simulation software, the simulation analysis is carried out, the effects, which are exerted by flow leakage, oil pump rotation speed, accumulator gas volume, overflow valve setting pressure, and so on, on both oil supply system dynamic characteristics and the nozzle inlet pressure are obtained. The simulation results show that the constant pressure oil supply system designed in this paper can effectively inhibit the flow pulsation and pressure fluctuation, and is of high reliability and stability.On the basis of the analysis of field test data, the relationship between nozzle flow measurement result and its main influencing factors (nozzle inlet pressure, oil temperature and air pressure) has been obtained by using multiple linear regression model,and the prediction model of nozzle flow metering results has been gained also.By comparing the difference in value between the measured flow rate and the forecast model, the prediction model is proved to be correct.The order from big to small of the influence degree of the there influence factors on the flow metering results has been obtained:nozzle inlet pressure> air pressure> lubricating oil temperature.Verified the importance of the guarantee of the stability of the nozzle inlet pressure and the oil supply system performance. Then experiments are conducted respectively under different supply pump speed, different accumulator volume and different relief valve setting pressure.The test results of nozzle inlet pressure are obtained under different condition.After comparison, the correctness of the simulation model is verified.