External flow choking at the landing phase of aircraft and re-entry vehicles

Dhanalakshmi, K and Deepak, N and Amrith, M and Kiridharan, R and Sanal Kumar, VR (2019) External flow choking at the landing phase of aircraft and re-entry vehicles. In: AIAA Propulsion and Energy Forum and Exposition, 2019, 19-22 August 2019, Indianapolis; United States.

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Abstract

In this paper 3D numerical studies have been carried out for improving the aerodynamic performance of aerospace vehicles at ground effect during takeoff and landing through a prudent design modification of the conventional fuselage. In this pilot work, using a validated 3D double precision density-based implicit standard k-ε turbulence model, the parametric analytical studies have been carried out to examine the external flow features of aircraft and re-entry spacecraft at ground effect. In the numerical study, a fully implicit finite volume scheme of the compressible, Navier�Stokes equations is employed. The validation and calibration of the 3D k-ε model is carried out based on the unique exact solution of boundary layer displacement thickness at the Sanal flow choking condition for 3D adiabatic flows (V.R.Sanal Kumar et al., AIP Advances, 8, 025315, 2018). We observed that facilitating a divergent channel effect at the bottom surface of the fuselage will be more beneficial for negating the external flow choking at ground effect during the close proximity flying. We inferred that under the identical flying conditions the chances of external flow choking at craft-in-ground (CIG) effect is less while comparing with the similar flying vehicles having the convectional fuselage. The fact is that if the ground clearance height to the chord length of the craft is too small, the developing boundary layers from either side of the surface (ground and the moving wing) can interact and develop a transient fluid-throat, leading to a choked flow, which will be delayed or negated for aircraft and re-entry space craft having fuselage bottom surface facilitated with diffuser channel shape. This study is a pointer towards for the fuselage and wings integrated geometry optimization for improving the overall aerodynamic performance of any flying craft at ground effect.

Item Type:	Conference Paper
Publication:	AIAA Propulsion and Energy Forum and Exposition, 2019
Publisher:	American Institute of Aeronautics and Astronautics Inc, AIAA
Additional Information:	Copyright of this article belongs to AIAA
Keywords:	Aircraft; Boundary layer flow; Boundary layers; Fuselages; Ground effect; Navier Stokes equations; Propulsion; Reentry; Turbulence models; Wings, Aero-dynamic performance; Analytical studies; Design modifications; Displacement thickness; Divergent channel; Finite volume schemes; Geometry optimization; Standard k epsilons, Air cushion vehicles
Department/Centre:	Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited:	28 Feb 2020 10:29
Last Modified:	28 Feb 2020 10:29
URI:	http://eprints.iisc.ac.in/id/eprint/64622

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