The research on ditching is indispensable for civil airplanes made in China to obtain the airworthiness certificates.The suction force effect in the ditching process is a hot and difficult research topic.In this paper...The research on ditching is indispensable for civil airplanes made in China to obtain the airworthiness certificates.The suction force effect in the ditching process is a hot and difficult research topic.In this paper,the explicit method is employed to solve the discrete Lagrangian finite element equations.The Eulerian finite volume method(FVM) is used to solve the Eulerian control equations;the fluid-solid coupling is realized through the general coupling method.The model of large civil airplane ditching is simulated by Dytran and the model test in tank is carried out in the same condition.Based on the analysis on the impacts and generation of the suction force and a numerical example,we obtain the accurate ditching pressure and pitch angle,as well as the results from the simulation and test.The estimated pressure and pitch angles are consistent with the results in the test.In the simulation,where the suction force is considered,the attitude-time history curve is very similar to the one of the tests,whereas the attitudes in the calculation without suction force is far different from the test.It can be concluded from the results that the suction force is the key impact in ditching calculation and can be simulated by general coupling method.In addition,different weight characteristics and different initial pitch angles both result in different pressures of ditching.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 10772013)the National Technology Research and Development Program of China (Grant No. 2012AA112201)the Aeronautical Science Foundation of China (Grant No. 20100251007)
文摘The research on ditching is indispensable for civil airplanes made in China to obtain the airworthiness certificates.The suction force effect in the ditching process is a hot and difficult research topic.In this paper,the explicit method is employed to solve the discrete Lagrangian finite element equations.The Eulerian finite volume method(FVM) is used to solve the Eulerian control equations;the fluid-solid coupling is realized through the general coupling method.The model of large civil airplane ditching is simulated by Dytran and the model test in tank is carried out in the same condition.Based on the analysis on the impacts and generation of the suction force and a numerical example,we obtain the accurate ditching pressure and pitch angle,as well as the results from the simulation and test.The estimated pressure and pitch angles are consistent with the results in the test.In the simulation,where the suction force is considered,the attitude-time history curve is very similar to the one of the tests,whereas the attitudes in the calculation without suction force is far different from the test.It can be concluded from the results that the suction force is the key impact in ditching calculation and can be simulated by general coupling method.In addition,different weight characteristics and different initial pitch angles both result in different pressures of ditching.
