Analytical and numerical predictions of boundary layer blockage in dual thrust motors

Chandrasekaran, N and Sankar, V and Sulthan Ariff Rahman, M and Murugesh, P and Ajith, S and Mohammed Niyasdeen, N and Kumaresh, S and Kumar, VRS (2018) Analytical and numerical predictions of boundary layer blockage in dual thrust motors. In: 54th AIAA/SAE/ASEE Joint Propulsion Conference, 2018, 9 - 11 July 2018, Cincinnati.

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Abstract

In this paper analytical and numerical predictions of boundary layer blockage at the Sanal flow choking condition for diabatic flows have been carried out. The Sanal flow choking 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. The analytical modeling effort for Sanal flow choking for diabatic flow is critically reviewed herein. Numerical simulations have been carried out using a validated unsteady, double precision, density-based, coupled second-order implicit, SST k-ω turbulence model. The CFD code is validated using the exact solution obtained from the closed-form analytical of V.R. Sanal Kumar [1] (AIP Advances, 8, 025315, 2018) at the Sanal flow choking condition with dynamic mesh. In the numerical study, we employed a fully implicit finite volume scheme of the compressible, Reynolds-averaged, Navier Stokes equations. We have obtained very good agreement between the analytically predicted and the numerically computed boundary layer displacement thickness at the sonic-fluid-throat of the dual-thrust motor. We found from the exact solutions that at the identical inflow conditions the analytically predicted 3D boundary layer blockage at the sonic-fluid-throat is 45.12 % lower than the 2D boundary layer blockage of a cylindrical port system with air as the working fluid obeying the compressible diabatic viscous flows theory. The results presented herein corroborated that any fluid flow solver, with an appropriate turbulence model, a best fit law of viscosity and wall-friction coefficient, calibrated using the proposed closed-form analytical model at the Sanal flow choking condition for diabatic flows with state-of-the-art is considered as credible for the grain design optimization of dual-thrust SRMs with the highest promising propellant loading density within the given envelope without manifestation of any internal flow choking leading to possible shock waves causing catastrophic failures.

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, AIAA.
Keywords:	Air; Analytical models; Atmospheric thermodynamics; Boundary layers; Friction; Navier Stokes equations; Propulsion; Shock waves; Turbulence models; Viscous flow, Analytical and numerical prediction; Catastrophic failures; Displacement thickness; Finite volume schemes; Inflow conditions; K-Omega turbulence model; Propellant loading; Reynolds averaged, Computational fluid dynamics
Department/Centre:	Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited:	10 Aug 2022 05:06
Last Modified:	10 Aug 2022 05:06
URI:	https://eprints.iisc.ac.in/id/eprint/75757

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