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
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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
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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:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 104
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Book Description
Author: C. E. Robinson
Publisher:
ISBN:
Category : Aerodynamics, Transonic
Languages : en
Pages : 38
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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
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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
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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: Earl A. Price (Jr.)
Publisher:
ISBN:
Category : Drag (Aerodynamics)
Languages : en
Pages : 182
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Book Description
Author: R. C. Bauer
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 30
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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:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1074
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Book Description
Author: Steven F. Yaros
Publisher:
ISBN:
Category : Aerodynamic load
Languages : en
Pages : 178
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Book Description
Author: C. E. Robinson
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 102
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Book Description
An experimental investigation was conducted to determine the effect of exhaust plume thermodynamic properties on a nonaxisymmetric nozzle afterbody. The model consisted of a strut-mounted cone-cylinder with an isolated nozzle afterbody. The shape of the nozzle afterbody was generally based on the early configurations of the ADEN design. An ethylene/air combustor was used to vary the thermodynamic properties by varying fuel-to-air ratio. Data were obtained at four fuel-to-air ratios representing exhaust plume temperatures of approximately 500 F (cold flow, fuel-to-air = 0), 1,200, 1,500, and 1,900 R. Pressure measurements of the nozzle afterbody surface were obtained from which drag coefficients along the rows of pressure orifices were calculated. The investigation was conducted over a range of Mach numbers from 0.6 to 1.4 at a Reynolds number per foot of 2.5 million. Generally, the nozzle afterbody drag decreased with increasing exhaust plume temperature over the entire Mach number range.
