Development Of Flow Separation Research Articles

Improvement of Wall-Corrections at the National Research Council’s Trisonic Wind Tunnel

The development of flow separation on a model tested at subsonic flow conditions reaching stall is not currently accounted for by the wall-correction methodology used at the National Research Council’s (NRC’s) 5 ft trisonic wind tunnel. Consequently, although this method provides accurate wall corrections during tests in prestall conditions, it is unable to generate reliable corrections in stall. The present paper investigates the possible improvements to the singularity representation of the model, which are paramount to the “one-variable” wall-correction methodology. This revision of the model representation is based on high-fidelity free-air computational fluid dynamics solutions for the NASA Common Research Model (CRM), which are validated by experimental datasets obtained from a semispan version of the CRM tested at the NRC’s 5 ft trisonic wind tunnel. The improved potential representation is tested on solid-wall experimental wind-tunnel data to present more reliable behavior of the wall interference correction estimates when substantial wing stalling is encountered.

Numerical Simulation for Engine/Airframe Interaction Effects of the BWB300 on Aerodynamic Performances

The engine/airframe interaction effects of the BWB300 on aerodynamic performances were analyzed by using the numerical simulation method. The BWB300 is a 300-seat Blended Wing Body airplane designed by the Airplane Concept Design Institute of Northwestern Polytechnical University. The engine model used for simulation was simplified as a powered nacelle. The results indicated the following: at high speed, although the engine/airframe interaction effects on the aerodynamic forces were not significant, the airframe’s upper surface flow was greatly changed; at low speed, the airframe’s aerodynamic forces (of the airplane with/without the engine) were greatly different, especially at high attack angles, i.e., the effect of the engine suction caused the engine configuration aerodynamic forces of the airframe to be bigger than those without the engine; and the engine’s installation resulting in the different development of flow separation at the airframe’s upper surface caused greater obvious differences between the 2 configurations at high angles and low speed. Moreover, at low-speed high attack angles, the separated flow from the blended area caused serious distortion at the fan inlet of the engine.

Experimental and Numerical Modelling of Turbulent Flow over an Inclined Backward-Facing Step in an Open Channel

The contribution deals with the experimental and numerical modelling of the turbulent flow over an inclined backward-facing step in an open water channel. The modelling was carried out in the wide range of the Froude number covering the subcritical, supercritical and near critical regimes as well. The study was concentrated particularly on the development of flow separation and on changes of free surface. Numerical results obtained using the commercial software ANSYS CFX 12.0 for the two-equation SST model and the EARSM model were compared with experimental data obtained by means of PIV and LDA measuring techniques.