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Chou, D. C.

Publications and source records attributed to Chou, D. C..

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Boundary layer transition effects on flow separation around V/STOL engine inlets at high incidence

Numerical methods for calculating laminar and turbulent boundary layer development around vertical-short take off and landing engine inlets at high incidence angles are investigated. Various transition models were compared and evaluated in calculations off flow separation bound inside the inlet. Results of the transition effects on the boundary layer characteristics at onset of separation for two types of engine inlet geometries are presented. Some of the numerical results are compared with existing wind-tunnel test data for scaled inlet models to demonstrate the effects of transition models in the numerical scheme. The effects of transition modeling on the boundary layer development are illustrated for typical engine operating conditions.

Chou, D. C.↗
NASA NTRS1981

Scale effects on turbulent boundary layer development and flow separation around V/STOL inlets at high incidence

Numerical methods for calculating laminar and turbulent boundary layers development around V/STOL engine inlets at high incidence angles, along with the procedures for predicting flow separation, are presented. Results of scale-effects, which are obtained by a numerical scaling procedure on the boundary layer characteristics and incidence angles at onset of separation are discussed. The interesting 'cross-over' phenomena, where the full-scale models actually exhibit earlier separation than the scaled-models, is illustrated for a typical V/STOL inlet at a certain operating condition. Some of the numerical results are compared with the existing wind-tunnel test data for a 1/6 scale inlet model to demonstrate the validity of the numerical approach.

Chou, D. C.↗
NASA NTRS1981

Three-dimensional turbulent boundary layer development and separation in V/STOL engine inlets at incidence with small-cross flow and curvature influences

The study concerns the influence of the three-dimensional cross flows on the compressible turbulent boundary layer development and flow separation prediction around V/STOL engine inlets at high incidence. The governing equations for the three-dimensional boundary layer flow with small-cross approximation are solved numerically on an intrinsic streamline coordinate system. Results are presented to illustrate the effects of small cross-flow, compressibility and streamline curvatures on the flow. Comparisons of the results with the wind tunnel data for scaled model and with data obtained from another existing compressible axisymmetric turbulent boundary layer scheme are included in the analysis.

Chou, D. C.↗
NASA NTRS1978

Methods for calculating the transonic boundary layer separation for V/STOL inlets at high incidence angles

A semi-empirical scheme for the prediction of transonic pressure distribution on the surface of V/STOL inlets at high incidence angles has been developed. The investigation is intended to improve the boundary layer calculation and separation prediction by including the effects of shock wave-boundary layer interaction into the Lewis Inlet Viscous Computer Program. Wind-tunnel results and theoretical pressure calculation for critical cases are used in constructing the transonic pressure distribution. The program, which describes the development of the boundary layer and predicts the possible flow separation, can handle the cases of inlets at high incidence angles where local supersonic region may occur in the flow.

Chou, D. C.↗
NASA NTRS1977

Prediction of Laminar and Turbulent Boundary Layer Flow Separation in V/STOL Engine Inlets

A description is presented of the development of the boundary layer on the lip and diffuser surface of a subsonic inlet at arbitrary operating conditions of mass flow rate, free stream velocity and incidence angle. Both laminar separation on the lip and turbulent separation in the diffuser are discussed. The agreement of the theoretical results with model experimental data illustrates the capability of the theory to predict separation. The effects of throat Mach number, inlet size, and surface roughness on boundary layer development and separation are illustrated.

Chou, D. C.↗
NASA NTRS1977

Prediction of laminar and turbulent boundary layer flow separation in V/STOL engine inlets

The paper provides a theoretical description of the development of the boundary layer on the lip and diffuser surface of a subsonic inlet at arbitrary operating conditions of mass flow rate, freestream velocity and incidence angle. Both laminar separation on the lip and turbulent separation in the diffuser are discussed. The agreement of the theoretical results with model experimental data illustrates the capability of the theory to predict separation. The effects of throat Mach number, inlet size, and surface roughness on boundary-layer development and separation are illustrated.

Chou, D. C.↗