Computational fluid dynamics challenges for hybrid air vehicle applications

Abstract

This paper begins by comparing turbulence models for the prediction of hybrid air vehicle (HAV) §ows. A 6 : 1 prolate spheroid is employed for validation of the computational §uid dynamics (CFD) method. An analysis of turbulent quantities is presented and the Shear Stress Transport (SST) kω model is compared against a kω Explicit Algebraic Stress model (EASM) within the unsteady Reynolds-Averaged NavierStokes (RANS) framework. Further comparisons involve Scale Adaptative Simulation models and a local transition transport model. The results show that the §ow around the vehicle at low pitch angles is sensitive to transition e¨ects. At high pitch angles, the vortices generated on the suction side provide substantial lift augmentation and are better resolved by EASMs. The validated CFD method is employed for the §ow around a shape similar to the Airlander aircraft of Hybrid Air Vehicles Ltd. The sensitivity of the transition location to the Reynolds number is demonstrated and the role of each vehicle£s component is analyzed. It was found that the ¦ns contributed the most to increase the lift and drag.

Variational Method-Based Trajectory Optimization for Hybrid Airships

“…Several research aspects [10][11][12][13][14] of hybrid airships, consisting of conceptual design, stability analysis, and trajectory optimization, must consider the strong coupling with environmental factors due to its power source and unique lift source. Regarding conceptual design [15], the most widely studied aspect of hybrid airships, multi-disciplinary models [16][17][18], have often been adopted to consider the coupling between the environment and airships.…”