Research On The Air Content Measurement System Of Aircraft Hydraulics

The air content in hydraulic oil has an aggressive influence on the aircraft hydraulic system.In this thesis,the measurement methods and principles of air content in hydraulic oil are analyzed.The measurement system is developed to measure the air contect in the aircraft hydraulic system.The measurement errors and its influencing factors are discussed by simulation and experimental.The main contents include the following parts:Chapterl:Introduction.The theory of air content and its influence on the aircraft hydraulic system are introduced.Research status of the air content measurement methods and measurement devices are given.The background,purpose and significance of the research are outlined.Chapter2:The general requirements of the system and the properties of the testing oil are given.The composition and principle of the measurement system are proposed.Mathematical models of the measurement system are built for measuring the air content value.The key parts of the measurement system are developed in detail,including the capacity of the glass chamber and the transmission mechanism.Chapter3:The measurement errors of the measurement system are analyzed by Matlab in detail.According to the error transfer theory,the comprehensive measurement errors are obtained to validate the working principle.Also the key parts of the measurement system are analyzed by FEA to demonstrate the correctness of structural parameters and the strength reliability of the system.Chapter4:The test rig is built to demonstrate the air content measurement system.The principle of the test rig is proposed.The method of determining the structural parameters of the pressurized tank is presented.The analysis of the strength and reliability based on Hypermesh are carried out.Chapter5:The experiments are carried out in the test rig of the air content measurement system.Through a series of preparatory experiments,like sensor tests,air state test and seal test,the correctness of the theoretical system design are verified.During the air content tests,repeatability test and temperature test,the measurement errors and its factors are analyzed.The test is consistent with the theory to meet the requirements.Chapter6:The research progress and achievement of this research are summarized.The future research and improvements are pointed out.