Computational Prediction of Isolated Performance of an Axisymmetric Nozzle at Mach Number 0.90 PDF Download
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Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781722119850 Category : Languages : en Pages : 30
Book Description
An improved ability to predict external propulsive performance was incorporated into the three-dimensional Navier-Stokes code PAB3D. The improvements are the ability to account for skin friction and external pressure forces. Performance parameters for two axisymmetric supersonic cruise nozzle configurations were calculated to test the improved methodology. Internal and external flow-field regions were computed using a two-equation kappa-epsilon turbulent viscous-stress model. The computed thrust-minus-drag ratios were within 1 percent of the absolute level of experimental data and the trends of data were predicted accurately. The predicted trend of integrated nozzle pressure drag matched the trend of the integrated experimental pressure drag over a range of nozzle pressure ratios, but absolute drag levels were not accurately predicted. Carlson, John R. Langley Research Center RTOP 505-62-30-01...
Author: Edsel R. Glasgow Publisher: ISBN: Category : Airframes Languages : en Pages : 714
Book Description
An experimental and analytical investigation of the installed thrust and drag of various isolated nozzle and twin-nozzle/aftbody configurations indicated that empirical correlations provide the best means of predicting aft- end performance, especially for the early stages of the aircraft design. Both subsonic and transonic isolated nozzle drag data were correlated using IMS (integral mean slope) as the geometric parameter. A correlation of twin-nozzle/aftbody drag data at subsonic and transonic speeds was developed by combining Spreiter's transonic similarity parameters with the IMS of the equivalent body of revolution. A correlation of inviscid MOC pressure drag, achieved through use of IMS combined with similarity parameters obtained from linearized supersonic flow theory, provided an accurate and rapid means of estimating drag for arbitrary axisymmetric boattail contours at supersonic speeds. Twin-nozzle/aftbody drag data at supersonic speeds was correlated with the equivalent body drag obtained from the axisymmetric MOC correlation. Improved thrust and drag performance was obtained by modifying the aft-end design of five selected aircraft configurations. The rationale for these modifications was derived from design guidelines and criteria developed during the program. Improvements in mission radius for a fixed takeoff gross weight aircraft were obtained, in general, by utilizing convergent-divergent nozzles, a horizontal wedge interfairing with the trailing edge terminating at the exit plane of the nozzles, a single vertical stabilizer, and a narrow lateral nozzle spacing.