Evaluation of Boattail Geometry and Exhaust Plume Temperature Effects on Nozzle Afterbody Drag at Transonic Mach Numbers PDF Download
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Author: L. L. Galigher Publisher: ISBN: Category : Aerodynamics, Transonic Languages : en Pages : 144
Book Description
An experimental program was conducted to investigate the interaction effects which occur between the nozzle exhaust flow and the external flow field associated with isolated nozzle afterbody configurations at transonic Mach numbers. Pressure data were obtained from three afterbody geometries with boattail angles of 10, 15, and 25 deg at Mach numbers from 0.6 to 1.5 at zero angles of attack and sideslip. Cold (High-pressure air) and hot (Air/ethylene combustion) jet test techniques were used to simulate and duplicate, respectively, the nozzle exhaust flow for a sonic jet installation. Nozzle exhaust temperature was varied from 540 to approximately 2,900 R. The most significant results pertain to those effects on boattail pressure drag caused by exhaust plume temperature and flow asymmetry (Model support strut induced). The differences obtained in boattail pressure drag between the cold jet simulation and hot jet duplication results were significant at nozzle pressure ratios representative for turbofan and turbojet engines at subsonic Mach numbers. Adjusting the cold jet nozzle pressure ratio to correct for changes in the exhaust plume specific heat ratio with temperature did not account for the differences observed. Flow asymmetry effects were Mach number and nozzle pressure ratio dependent and increased in severity as the boattail angle was increased.
Author: L. L. Galigher Publisher: ISBN: Category : Aerodynamics, Transonic Languages : en Pages : 144
Book Description
An experimental program was conducted to investigate the interaction effects which occur between the nozzle exhaust flow and the external flow field associated with isolated nozzle afterbody configurations at transonic Mach numbers. Pressure data were obtained from three afterbody geometries with boattail angles of 10, 15, and 25 deg at Mach numbers from 0.6 to 1.5 at zero angles of attack and sideslip. Cold (High-pressure air) and hot (Air/ethylene combustion) jet test techniques were used to simulate and duplicate, respectively, the nozzle exhaust flow for a sonic jet installation. Nozzle exhaust temperature was varied from 540 to approximately 2,900 R. The most significant results pertain to those effects on boattail pressure drag caused by exhaust plume temperature and flow asymmetry (Model support strut induced). The differences obtained in boattail pressure drag between the cold jet simulation and hot jet duplication results were significant at nozzle pressure ratios representative for turbofan and turbojet engines at subsonic Mach numbers. Adjusting the cold jet nozzle pressure ratio to correct for changes in the exhaust plume specific heat ratio with temperature did not account for the differences observed. Flow asymmetry effects were Mach number and nozzle pressure ratio dependent and increased in severity as the boattail angle was increased.
Author: C. E. Robinson Publisher: ISBN: Category : Aerodynamics, Transonic Languages : en Pages : 38
Book Description
An experimental investigation was conducted to study the effects of Reynolds number variation on isolated nozzle afterbody performance. A strut-mounted cone-cylinder model with three separate afterbody configurations for Aerospace Research and Development (AGARD) was used for this investigation. This program was conducted in two phases distinguished by the model size and the wind tunnels used to obtain the experimental results. The effect of tunnel wall porosity on nozzle afterbody (NAB) performance was investigated.
Author: James L. Jacocks Publisher: ISBN: Category : Airplanes Languages : en Pages : 36
Book Description
The development of a computer program for solving the compressible, axisymmetric, mass-averaged Navier-Stokes equations is described. The basic numerical algorithm is the MacCormack explicit predictor-corrector scheme. Turbulence modeling is accomplished using an algebraic, two-layer eddy viscosity model with a novel modification dependent on the streamwise gradient of vorticity. Comparisons of computed results with experimental data are presented for several nozzle-afterbody configurations with either or simulated plumes. (Author).
Author: Earl A. Price (Jr.) Publisher: ISBN: Category : Aerodynamics, Transonic Languages : en Pages : 416
Book Description
A comprehensive experimental program was conducted to provide nozzle-afterbody data with a minimum interference support system on a 1/9-scale F-16 model and to determine the interference induced on the afterbody-nozzle region by a sting, a wingtip, and a strut model support system. The investigation was conducted over the Mach number range from 0.6 to 1.5 and at angles of attack from 0 to 9 deg. Interference was evaluated by comparison of nozzle-afterboy axial and normal forces obtained from integrating pressure data. The results include parametric studies of the efects of various components of the wingtip support system (i.e., the support blade axial position, wingtip boom diameter, boom spacing, and boom-tip axial location). High-pressure air at ambient temperature was utilized for exhaust plume simulation. The results indicate that a sting support passing through the nozzle with the jet effects simulated by an annular jet appears to offer a minimum interference support system for the type of nozzle-afterbody test described in this report.
Author: R. C. Bauer Publisher: ISBN: Category : Airplanes Languages : en Pages : 30
Book Description
A highly simplified analysis was used to derive an expression for estimating the induced afterbody drag caused by the turbulent jet-mixing process. The approach estimates the induced velocity produced by the jet-mixing process and uses small perturbation concepts to estimate the resulting pressure change on the afterbody surface from which the induced afterbody drag coefficient is obtained. The theoretical induced afterbody drag (entrainment drag) is combined with the maximum jet plume diameter blockage condition to form a correlation method that accounts for the effect of jet area ratio, exit angle, total temperature, molecular weight and ratio of specific heats for a given external stream Mach number, Reynolds number, and afterbody geometry. For verification, the correlation method was used to predict the drag of an H2 and C2H4 jet from the measured drag of an N2 jet and to predict the drag of a hot jet from the measured drag of a cold jet for both the 15- and 25-deg AGARD afterbody configurations in the Mach number range from 0.6 to 1.5. The average accuracy of the correlation method is better than 10% for both afterbody configurations and is 40 to 50 % more accurate than a correlation method based only on the blockage parameter. A brief numerical study indicates that the major parameter which correlates the jet entrainment effect is the product of the jet gas constant and total temperature. (Author).
Author: C. E. Robinson Publisher: ISBN: Category : Aerodynamics, Transonic Languages : en Pages : 98
Book Description
Results of an experimental and analytical research investigation on nozzle/afterbody drag are presented. Experimental afterbody (and boattail) drag coefficients and pressure distributions are discussed for an isolated, strut-mounted nozzle/afterbody model for the Mach number range from 0.6 to 1.5. Some data are also given for free-stream unit Reynolds numbers from one million to approximately four million per foot. The experimental data were obtained for the basic model with an air-cooled and a water-cooled Ethylene/air combustor to provide hot-jet duplication as well as cold-jet simulation. The temperature of the nozzle exhaust gas was varied from 530R (burner-off) to approximately 2500R for several nozzle pressure ratios from jet-off to those corresponding to a moderately under-expanded exhaust plum. The initial series of experiments was conducted with the air-cooled combustors, and the effect of jet temperature on afterbody drag was somewhat masked by the effects of the secondary airflow from the cooling air. The general trend, however, shows a decreasing afterbody drag with increasing exhaust gas temperature and with decreasing secondary airflow at a fixed nozzle pressure ratio. (Modified author abstract).
Author: L. L. Galigher
Author: L. L. Galigher
Author: 
Author: C. E. Robinson
Author: James L. Jacocks
Author: Earl A. Price (Jr.)
Author: Earl A. Price (Jr.)
Author: R. C. Bauer
Author: 
Author: Steven F. Yaros
Author: C. E. Robinson