Numerical simulation of raindrops distribution on canopy surface of hemispherical parachute in heavy rain via two-phase flow approach

Abstract

The descent of parachute and re-entry capsule in heavy rain has been rarely researched yet. Study of raindrops distribution on canopy surface in heavy rain environment is a key step in the whole research. In this paper, the discrete phase model of two-phase flow approach is applied to simulate the raindrop trajectories in order to research the problem of raindrops distribution on canopy surface when parachute and re-entry capsule are descending in heavy rain. Numerous cases based on different rainfall rates and vertically descending velocities of a simple hemispherical parachute and re-entry capsule are numerically calculated preliminarily. The simulation results are presented, and it is found that the raindrops trapped by the canopy surface are not even-distributed, and raindrops are concentrated near the bottom edges of canopy surface as a result of high-pressure zone enclosed by the parachute; there is a corresponding critical value of descending velocity of parachute and re-entry capsule which determines whether the raindrops will be trapped by the canopy surface for one particular rainfall rate; only above the critical value of descending velocity of parachute and re-entry capsule the raindrops can be trapped by the canopy surface. The conclusions will be of great significance to the further research of the problem of descent of parachute and re-entry capsule in heavy rain.