Design And Implementation Of An Airborne Optical Fiber Fuel Measurement System

Aircraft airborne fuell measurement system is the most important subsystem of the fuel system.Two types of technologies(float fuel level measurement and the capacitance fuel level measurement)are mainly applied to the present aircraft.Nowadays,ultrasonic fuel level measurement technology has been used on some foreign aircraft.All these fuel level measurement technologies need to introduce electrical signals into the fuel tank,which may result in safety risks.The optical fiber fuel level measurement technology is new development trendency of aircraft fuel gauging technology since it is featured with the advantages such as intrinsic safety,small size,light weight,no electromagnetic interference and so on.The paper presents a new airborne optical fiber fuel level measurement technology and explores the research on application of fiber-optic grating to aircraft fuel measurement based on the theory of fiber-optic grating,the characteristics of aircraft fuel measurement and related content of fuel quantity calculation algorithm.The primary research covers basic deduction of the theory of the Bragg grating measurement technology and introduction to the pressure measurement principle about the fiber grating,which provides the theoretical basis for parameters available for the design of the optical fiber grating fuel level sensor.Also,the qiartz fiber is selected as sample trial production.The paper describes a design proposal concerning liquid level sensor based on the FBG pressure sensor array,undertakes the trial production of the prototype,and presents a basic algorithm of liquid height.It calculates the pressure of sensor based on the acquisition on offset of center wavelength and calculates the wet height of probe immersed in the fuel in accordance with the linear regression theory.It presents design proposal for FBG signal demodulation analyzer based on the principle of wavelength tunable filter and undertakes the trial production of the prototype in order to acheive the high accuracy measurement on the wavelength signal of FBG sensor array.Besides,the basic proposal for design of fuel quantity calculation module which uses dual-redundancy processing module that selects MPC8313 as the core processor is recommended.Regarding software,layout principle and method for fuel liquid sensor is discussed.A typical fuel tank mode is selectedl as the sensor layout.The quality characteristic database has been established according to the layout results and the principle and method of database establishment has been described briefly including the algorithm of calculating the fuel quantity.Mathmatical module is established in aircaraft airframe cpprdomate.Optimum Liquid height data is recommmended to calculate the fuel level angle.If such data is unavailable,such methods as aircraft overload and attitude angle can be used to calculate the fuel level angle.The fuel volume data can be obtained after the fuel level angle is known in conjunction with the liquid level and referrence to the established quality proporty database.In addition,optical fiber liquid sensor test software is prepared,which can test the liquid height measurement accurancy,System test software is also developed.The test condition is established via bus interface and principle verfication test on function of optical fiber liquid measurement system is developed.