Flow Simulation in Interference Region of Multiple Slender Bodies with Inclined Strap-Ons at Subsonic Speed

Abstract

The Launch vehicles often incorporate multiple strap-on boosters as a design feature to achieve enhanced performance goals. The analysis of pressure distributions are very important for designing the multiple slender bodies with strap-ons which are important for different trajectory paths, performance of mathematical analysis and design of typical launch vehicle. During atmospheric flight, the launch vehicle like as PSLV & GSLV with strap-ons moves at subsonic speed, for which aerodynamic interference in the form of pressure waves can occur between multiple slender bodies placed in close proximity. In the present work, experiment as well as computational analysis were done over the model of launch vehicle with two strap-ons at free stream flow velocity V∞ of 20 metre/secod and at 4°angle of attack by varying the the strap-on incidences ranging from 0° to 6°. Measurements of surface pressure distribution in the interference region were done with the help of open circuit subsonic wind tunnel. Computational analysis have been done with FLUENT software along with the turbulence modeling i.e. (SST) k- ω model to understand the complex flow pattern over the model. The computations involve choice of discretization, grid generation, solution technique and analysis of results. A finite volume approach was used for discretization. The 3-D structured grid has been generated by using the software GAMBIT over the multiple slender bodies with two strap-ons to validate the obtained results from the experiments. Results are compared which shows a good agreement between numerical and experimental values.