Preliminary Assessment of the Boundary Layer Ingestion Benefit for the D8 Aircraft

Speaker: Shishir A. Pandya, NAS Applied Modeling & Simulation Branch
April 3, 2014

Presentation

Abstract

The benefit of boundary layer ingestion (BLI) is quantified with both experimental and computational techniques for the D8 aircraft concept. The D8 is a next-generation subsonic transport concept in the Boeing 737 class that uses various means to improve fuel efficiency and lower environmental impact. A set of tests were carried out in the NASA Langley 14x22 wind tunnel (WT) on 1:11 scale models of the D8 along with a side-by-side computational effort. A 1:20 scale unpowered configuration model was previously used to establish the aircraft behavior and was presented in a previous AMS seminar (June 2012). Further validation is carried out using the 1:11 scale unpowered model test results from the 14x22 WT to establish the validity of the computational approach. The computational approach consists of solutions on overset surface and volume grids using Overflow, a viscous overset RANS CFD solver with an actuator-disk propulsor model.

The validation is followed by a comparison of the performance of two D8 configurations:a traditional, non-BLI configuration, and a configuration that uses BLI propulsors. Mechanical flow power needed to achieve cruise is used as the metric for directly comparing the two powered models. This comparison is used to obtain the BLI benefit.

The BLI configuration is shown to require 6% less electrical power by the experiment and 9% less mechanical flow power by the computations relative to the conventional configuration at the simulated cruise condition. It is shown that the benefit results from reduced entropy generation associated with wake and jet mixing in the BLI configuration.

Biography

Shishir Pandya is a member of the Applied Modeling and Simulation Branch at NASA Ames Research Center. In the field of Computational Fluid Dynamics (CFD) he performs research in overset mesh generation and flow solution methods. His past and current research topics include hyperbolic mesh generation, overset surface mesh generation, prismatic meshes, power boundary conditions, and low-Mach preconditioning. He has also applied inviscid Cartesian methods and viscous overset methods to various aircraft and spacecraft. His application projects have included NASA's Ares-I rocket (stage separation, and booster failure analysis), the SHARP-L1 re-entry vehicle, investigation of rocket launch from the back of an aircraft, the Harrier aircraft, and the Canard Rotor/Wing (CRW) aircraft. During these application investigations, he has looked at various flow phenomena such as jet impinging on ground and in cross flow, proximity aerodynamics of separating vehicles, low-speed flow for aircraft, and high-speed flow for rockets and re-entry vehicles. His current project is to look at the effects of Boundary Layer Ingestion in an engine placed on the rear fuselage of the D8 "Double-Bubble" aircraft.

Shishir received his undergraduate degree in Mechanical and Aeronautical Engineering from UC Davis in 1991 and his Masters and doctorate in Mechanical Engineering from UC Davis in 1993, and 1998 respectively.