May-Fun Liou

Mail-Slot Nacelle Shape Design for N3-X Hybrid Wing-Body Configuration

System studies show that NASA’s N3–X hybrid wing-body aircraft with a turboelectric distributed propulsion system using a mail-slot inlet/nozzle nacelle can meet the environmental and performance goals for N+3 generation transports (three generations beyond the current air transport technology level). In this paper, we present Navier-Stokes flow simulations of N3–X on hybrid unstructured meshes, including the mail-slot propulsor. A novel body force model generation approach is suggested for a realistic and efficient representation of flow turning, pressure rise and losses resulting from the fan blades and the inlet-fan interactions. A new version of mail-slot installation on the N3-X configuration was tested. An optimal shape design of the mail-slot nacelle surface was conducted to reduce the strength of shock waves and flow separations on the cowl surface.

Mesh-Based Microstructure Representation Algorithm for Simulating Pore-scale Transport Phenomena in Porous Media

In the conventional CFD approach, a prescribed physical domain of porous medium with existing fluid-solid interface is mapped onto a computational domain, which is then geometrically discretized by mesh generation. This would be formidable task if hundreds or thousands of pores of irregular shapes are to be mapped. In the new approach developed here, the geometry discretization is made easy by taking the reverse sequence of conventional steps. First, the outline of the computational domain is selected to represent the physical domain of interest.

Pore Scale Simulation of Combustion in Porous Media

This paper describes an improved methodology for studying combustion in porous media in pore scale. Porous media combustion is one technology having advantages over the conventional combustion system. Examples of combustion in porous media are presented to show the potential application of the present mesh-based microstructure representation algorithm (MBMRA).

Aerodynamic Design of the Hybrid Wing Body with Nacelle: N3-X Propulsion-Airframe Configuration

The Hybrid Wing Body (HWB) aircraft is of great interest for future transport concepts due to its promises of reduced aircraft noise, nitrous-oxide emissions, and fuel consumption. A design parameterization method for HWB configurations with mail slot nacelle has been developed for a fast exploration of design space in conceptual and preliminary design phases of a HWB configuration. A HWB planform model by Laughlin was implemented, and the Class Shape Transformation (CST) airfoil generation method by Kulfan was utilized to construct the needed geometry for computational high fidelity aerodynamic simulations. Geometric constraints for the parameterization such as internal cabin and cargo hold layouts were imposed on the geometry generation. A CFD simulation was performed for a HWB configuration generated by the current geometric modeler, clearly showing a significant effect of the installed nacelle on the flowfield.

Mitigation of Adverse Effects Caused by Shock Wave Boundary Layer Interactions Through Optimal Wall Shaping

Abstract: It is known that the adverse effects of shock wave boundary layer interactions in high speed inlets include reduced total pressure recovery and highly distorted flow at the aerodynamic interface plane (AIP). This paper presents a design method for flow control which creates perturbations in geometry. These perturbations are tailored to change the flow structures in order to minimize shock wave boundary layer interactions (SWBLI) inside supersonic inlets. Optimizing the shape of two dimensional micro-size bumps is shown to be a very effective flow control method for two-dimensional SWBLI. In investigating the three dimensional SWBLI, a square duct is employed as a baseline. To investigate the mechanism whereby the geometric elements of the baseline, i.e. the bottom wall, the sidewall and the corner, exert influence on the flow’s aerodynamic characteristics, each element is studied and optimized separately. It is found that arrays of micro-size bumps on the bottom wall of the duct have little effect in improving total pressure recovery though they are useful in suppressing the incipient separation in three-dimensional problems. Shaping sidewall geometry is effective in re-distributing flow on the side wall and results in a less distorted flow at the exit. Subsequently, a near 50% reduction in distortion is achieved. A simple change in corner geometry resulted in a 2.4% improvement in total pressure recovery.