Experimental Study On Icing Of Fuel Pipeline

When airplanes operate in a cold temperature environment,the water in the fuel will freeze.As the ice break off from the pipe wall,it may clog filters,valves,pumps and other components of the fuel supply system or cause system malfunction.As a result,fuel flow to engines can be insufficient or engines occurs to stop,which is one of the important factors of threatening flight safety.In this paper,the key technical problems and approaches that need to be solved in aircraft fuel system icing test are studied,including fuel preparation saturated with water,fuel recycling method and constant fuel temperature controlling measure.On these bases,a test platform for fuel pipe icing test is established,providing important technical support for fuel icing airworthiness certification.In this paper,the water characteristics in the fuel,the principle and effective factors of fuel pipe icing were studied theoretically.Besides,the water characteristics,water configuration methods and icing test methods in the fuel were studied experimentally.Specifically,it includes:(1)The research on the effective factors of dissolved water content in the fuel determined the choice of test conditions and fuel type.By using high-low temperature test chamber,the water characteristics in the domestic fuel(No.3 aviation kerosene)based on different temperature conditions were studied,and the functional relationships between temperature and saturated water content in the fuel and fuel density,respectively,were obtained.(2)A new type of electrical impulse atomizer was used to optimize water configuration methods at room temperature,which achieved uniform mixing of a small amount of water(0.6-3.2ml/min)and fuel.As a result,the water content in the fuel was controllable in the range of 60-320 ppm.On this basis,a small water configuration and circulation test system of fuel at normal temperature was established and carried out water configuration tests in the fuel of different water content under different environmental conditions.Karl Fischer method was used to analyze water content of samples from multiple sampling points.The results suggested that the modified water configuration method in the fuel,by contrast,was simpler to operate and had better stability.The fuel saturated with water can be prepared in the temperature range of 0-30℃.The error rate of water content in supersaturated fuel measured by Karl Fischer method was less than 6%.(3)The experimental method of fuel pipe icing system was studied,of which matching tank was modified,and water configuration in the fuel below 0℃ was accomplished.The experiment of fuel pipe icing was launched,and the phenomenon of fuel pipe icing recurred.The corresponding curves between the ice weight of in the test pipe and fuel temperature,water content and flow velocity,respectively,were obtained.