Numerical simulation of the aerial drop of water for fixed-wing airtankers

To evaluate the effectiveness of water dropping by fixed-wing airtanker, CFD simulation based on Eulerian multiphase flow model is employed to simulate the dumping process. First, the numerical method is validated by wind tunnel test of airtanker. Results show a satisfied agreement in water precipitation and transient local velocity distribution with test data. Secondly, the full scale water dump model of AG-600 amphibian is developed using sliding mesh technique. Working conditions such as drop height, flight speed, cross wind velocity, atmosphere temperature, released mode and volume are tested. The precipitation area, shape, location and density distribution are compared and analyzed. Compared to the real-scale drop tests of comparable aircraft, the coverage area of water is reasonable, satisfying the designed requirement. Finally, the layout of the water cups in the measurement are inferred from the CFD results. The research of this paper helps to assess the water dumping performance of airtankers and to optimize working conditions.