Aerial Refueling System Design Andanalysis For XX Aircraft

Aerial refueling is one of the key technologies to meet the requirements of large flight radius, long retention time in the air, rapid flexible capability and large bomb-carrying capacity for modern combat aircrafts. Based on the task of “technical study on aerial refueling for XX aircraft”, the aerial refueling system was designed and analyzed in detail.The research involves the following aspects:1. The development history and the operating principle of aerial refueling technology were systematically summarized, its research status and application at home and abroad were reviewed, and the major existing problems were analyzed.2. In accordance with the design specification of the ground pressure refueling system and aerial refueling system, the similarities and differences between these two systems were analyzed including: firstly, the structures of ground pressure refueling system and aerial refueling system are almost same and one refueling system should satisfy the capacity of both systems; secondly, the technical index requirements of aerial refueling system is higher than the counterparts of ground pressure refueling system, this is because the average flow rate of the former is higher than the latter that brings some problems such as: shorter refueling time, higher requirements for ventilation ability of vent system, larger surge pressure of pipeline and more complicated barycenter variation law during refueling in the air. Thus, not only the higher refueling flow rate issue should be taken into account, but also the series issues of design, caculation and checking brought by the higher flow rate when converting ground pressure refueling system into aerial refueling system; thirdly, the settings of indication signal, control switch and illumination of aerial refueling system are different from ground pressure refueling system in consequence of the demands of aerial docking and so on. These matters should be paid more attention during the modification of the system; finally, the settings of control attachments, the refueling flow rate control, the requirements of static electricity control and the requirements of working environment of aerial refueling system are the same as those of ground pressure refueling system, so the standards of the latter could be used by the former.3. The design scheme of the aerial refueling system of a certain type aircraft has been proposed, which consists of two sections, one is structure and main devices selection, and the other one is design of pipeline. In the section 2, the refueling time and the flow rate match has been calculated based on commercial software-Flowmaster. The result shows that the design of aerial refueling system meets the previous design demands.4. Based on the design scheme of the aerial refueling system, three problems which are focused on in the system have been calculated including the ventilation ability of vent system, the surge pressure of pipeline and the range of barycenter variation. The results reveal: firstly, the vent system of the design scheme has favorable ability of spilling fuel which could ensure the pressure in all the fuel tanks below the specified value of relevant standard and the availability of vent system; secondly, when shutdown the refuel valves in normal process, 2s and 1.5s, the surge pressure of pipeline are below the inspection pressure of the system. However, when the refuel valves is shutdown in 1s, the surge pressure at the refuel valves of fuel tank No.3 and No.4 exceed the inspection pressure of the system. Therefore, during the refueling process, the switch time of the fuel valves should be controlled strictly to prevent exorbitant surge pressure damage the system; finally, the variation of aircraft barycenter is always in the acceptable limits in the whole aerial refueling process.