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Prediction of 3d boundary layer blockage and the grain design optimization of hvt dual-thrust hybrid rockets

Sanal Kumar, VR and Sankar, V and Chandrasekaran, N and Murugesh, P and M, SAR (2018) Prediction of 3d boundary layer blockage and the grain design optimization of hvt dual-thrust hybrid rockets. In: 54th AIAA/SAE/ASEE Joint Propulsion Conference, 2018, 9 - 11 July 2018, Cincinnati, Ohio.

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Official URL: https://doi.org/10.2514/6.2018-4446


An innovative and powerful closed-form analytical model is developed for predicting the 3D boundary layer blockage in high-velocity transient (HVT) dual-thrust hybrid rockets obeying the compressible diabatic viscous flow theory. This is the continuation of our previous connected paper pertaining to the boundary layer blockage prediction at the Sanal flow choking condition for adiabatic flows (V. R. Sanal Kumar et al. [1], AIP Advances, 8, 025315, 2018). The Sanal flow choking for diabatic flow is a unique condition of any internal flow system at which both the thermal choking (Rayleigh flow effect) and the wall-friction induced flow choking (Fanno flow effect) occur at a single sonic-fluid-throat location. A dual-thrust hybrid rocket with constant upstream cylindrical port having large length-to-diameter ratio (l/d > 27) is selected as a three-dimensional physical model. During the numerical simulation, for achieving the Sanal flow choking effect the igniter jet Mach number is selected based on the thermal choking condition and the average wall friction coefficient of the cylindrical port is selected based on the Fanno flow model. The beauty and novelty of the Sanal flow choking condition for diabatic flow is that, without missing the real flow physics we could exactly predict the 3D boundary layer blockage of the dual-thrust hybrid rocket motors with different liquid fuel and liquid oxidizer combinations aiming for achieving the highest possible solid fuel or solid oxidizer loading density coupled with high ΔV benefits without creating any internal flow choking effect within the given envelop during the entire period of its operation. We concluded that, though the boundary layer blockage is relatively higher, the liquid oxidizer or liquid fuel with the highest heat capacity ratio is the best choice for increasing the propellant loading density without inviting any undesirable internal flow choking phenomenon leading to catastrophic failures of the rocket motor due to the formation of pressure overshoot as a result of the internal shock waves. Note that the pressure ratio for choking will increase while increasing the heat capacity ratio of the gas. The closed-form analytical model presented herein is a brilliant tool for the validation of 3D Navier-Stokes solvers for the design optimization of any HVT internal flow system involving the transfer of heat with confidence. Furthermore, using the closed-form analytical model at the Sanal flow choking condition for diabatic flows, the HVT rocket designers can accurately predict the possibilities of the internal flow choking in the dual-thrust hybrid rockets at the given jet flow Mach number for a credible decision making for improving its propellant loading density within the given envelope lucratively.

Item Type: Conference Paper
Publication: 2018 Joint Propulsion Conference
Publisher: American Institute of Aeronautics and Astronautics Inc, AIAA
Additional Information: The copyright for this article belongs to the American Institute of Aeronautics and Astronautics, Inc.
Keywords: Aerodynamics; Analytical models; Decision making; Forecasting; Friction; Liquid fuels; Liquids; Mach number; Navier Stokes equations; Propellants; Propulsion; Rockets; Shock waves; Specific heat, Catastrophic failures; Design optimization; Hybrid rocket motors; Length to diameter ratio; Liquid oxidizers; Navier-Stokes solver; Propellant loading; Solid oxidizers, Boundary layers
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited: 14 Aug 2022 06:18
Last Modified: 14 Aug 2022 06:18
URI: https://eprints.iisc.ac.in/id/eprint/75752

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