Flow field characteristics and dynamics of internal supply chamber separating from UAV considering effect of deceleration parachutes

The supply chamber can be internally carried in the Unmanned Aerial Vehicle (UAV), and be separated in the target area by deploying a deceleration parachute swiftly. The agilityand cost-effectiveness ratio of the airdropping can be improved significantly with this concept. However, the supply chamber is snugly assembled in the internal bay of UAVand has comparable mass with the UAV, which leads to stronger aerodynamic interference in the separation flow field. This is different from the separation of internal weapons from the combat aircraft. During the separation, the inflationand deployment of the deceleration parachute will cause highly unsteady flow fieldsand aerodynamic interference with the supply chamberand UAV. This makes it difficult for traditional methods based on the Arbitrary Lagrangian-Eulerian (ALE) method to analyze the impact of deployment of the deceleration parachute on the separation dynamic characteristics. In this paper, a parachute deployment equivalent method combining the inflation time methodand wall assumption is proposed. By combining with Computational Fluid Dynamics (CFD) coupled with the 6 Degree Of Freedom (6DOF) equation method, an equivalent model of multi body separation accompanied by parachute deployment with Eulerian description is constructed. An integrated simulation analysis of the internal separation with the parachute deployment process for the supply chamber is achieved, and the impact of separation trajectory parametersand aerodynamic interference for the supply chamber is explored. Result shows that the proposed equivalent method can effectively analyze the deployment of the deceleration parachute. The trajectory of the supply chamber is relatively stable, while the UAV is affected by significant pitching interference during separationand parachute deployment. The impact of the analyzed variables on separation dynamics is nonlinear, and it is necessary to optimize the separation scheme further. Works in this paper can be the foundation for the design of UAV systemsand separation schemes.