Comparison of High-Fidelity Computational Tools for Wing Design of a Distributed Electric Propulsion Aircraft

Abstract

A variety of tools, from fundamental to high order, have been used to better understand applications of distributed electric propulsion to aid the wing and propulsion system design of the Leading Edge Asynchronous Propulsion Technology (LEAPTech) project and the X-57 Maxwell airplane. Three highfidelity, Navier-Stokes computational fluid dynamics codes used during the project with results presented here are FUN3D, STAR-CCM+, and OVERFLOW. These codes employ various turbulence models to predict fully turbulent and transitional flow. Results from these codes are compared for two distributed electric propulsion configurations: the wing tested at NASA Armstrong on the Hybrid-Electric Integrated Systems Testbed truck, and the wing designed for the X-57 Maxwell airplane. Results from these computational tools for the high-lift wing tested on the Hybrid-Electric Integrated Systems Testbed truck and the X-57 high-lift wing presented compare reasonably well. The goal of the X-57 wing and distributed electric propulsion system design achieving or exceeding the required " = 3.95 for stall speed was confirmed with all of the computational codes. Nomenclature Symbols # drag coefficient a angle of attack, degrees #,%&'()* drag coefficient, pylons contribution Δ delta #,,-). drag coefficient, wing contribution #,/0 drag coefficient, tip nacelles contribution Acronyms #,10" drag coefficient, high-lift nacelles contribution BSL Menter kbasic turbulence model " lift coefficient CFL pseudo time advancement Courant-Friedrichs-Lewy ",344 effective lift coefficient: " + ",%5(% DEP distributed electric propulsion ",678 maximum lift coefficient HLN high-lift nacelles ",%5(% lift coefficient from the contribution of propeller thrust in lift direction KCAS KEAS knots calibrated airspeed knots equivalent airspeed 6

Large-scale multidisciplinary optimization of an electric aircraft for on-demand mobility

“…As stated previously, the camber is adjusted to match the lift coefficient at zero angle of attack. For the cruise configuration with no high-lift nacelles, we find that the lift curve slope matches well and the drag polar falls in between the predictions with fully turbulent and transition models [30]. For the high-lift configuration, we include the propeller force components, and we find that the lift curve slope is under-predicted at low angles of attack.…”

“…We validate the aerodynamics model (minus the C D0 term) against RANS CFD predictions [29,30] using OVER-FLOW, STAR-CCM+, and FUN3D in Fig. 4.…”

“…The propeller-wing aerodynamics model shows good agreement with CFD data except for the drag at high angles of attack. The cruise data is from Borer et al[29] and the high-lift data is from Deere et al[30].…”

Modeling hybrid polymer–nanometal lightweight structures

“…With respect to propulsion, open rotor engines [3] or boundary-layer ingestion [10] is promising options that significantly increase fuel efficiency. Electric propulsion [6], which may be distributed [5], is also attractive options. Biofuels are certain to be an important contributor to the sustainability of any propulsion system that continues to use hydrocarbons [11].…”

Exploring the Effects of Installation Geometry in High-Lift Propeller Systems

“…Consisting of an array of propellers installed upstream of the wing leading edge, a HLPS accelerates the flow observed by the wing, thereby increasing the wing's effective lift coefficient. In the case of the X-57, lift coefficients of 4.5 or greater are possible during takeoff, approach, and landing with moderate blowing of a flapped wing [11][12][13]. The propeller blades (of the HLPS) then conformally fold away against their nacelles during cruise to reduce drag [14].…”