scholarly journals Crow instability effects on the exhaust plume mixing and condensation

1999 ◽  
Vol 7 ◽  
pp. 66-79 ◽  
Author(s):  
S. Brunet ◽  
F. Garnier ◽  
P. Sagaut
Keyword(s):  
Exhaust Plume ◽  
Crow Instability

Large eddy simulation of aircraft wake vortices within homogeneous turbulence - Crow instability

AIAA Journal ◽  
2000 ◽  
Vol 38 ◽  
pp. 292-300 ◽  
Author(s):  
Jongil Han ◽  
Yuh-Lang Lin ◽  
David G. Schowalter ◽  
S. P. Arya ◽  
Fred H. Proctor
Keyword(s):  
Large Eddy Simulation ◽  
Homogeneous Turbulence ◽  
Wake Vortices ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Aircraft Wake ◽  
Crow Instability

Analysis of three-dimensional ducted and exhaust plume flowfields

AIAA Journal ◽  
1978 ◽  
Vol 16 (8) ◽  
pp. 823-830 ◽  
Author(s):  
Sanford M. Dash ◽  
Paul D. DelGuidice
Keyword(s):  
Three Dimensional ◽  
Exhaust Plume

Calculation of exhaust plume structure and emissions of the ER 2 aircraft in the stratosphere

1996 ◽  
Vol 101 (D2) ◽  
pp. 4025-4032 ◽  
Author(s):  
M. R. Anderson ◽  
R. C. Miake-Lye ◽  
R. C. Brown ◽  
C. E. Kolb
Keyword(s):  
Exhaust Plume ◽  
Plume Structure

Thrust Measurements using Acoustic Sensing on a Turbofan Engine Exhaust Plume

2021 ◽  
Author(s):  
John Gillespie ◽  
Kevin T. Lowe ◽  
Wing Ng ◽  
Loren Crook ◽  
Victor Oechsle
Keyword(s):  
Engine Exhaust ◽  
Turbofan Engine ◽  
Acoustic Sensing ◽  
Exhaust Plume

Numerical evaluation of the exhaust-direction effects on plume flow and helicopter infrared radiation under hover and cruise statuses

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Zongyao Yang ◽  
Yong Shan ◽  
Jingzhou Zhang
Keyword(s):  
Radiation Intensity ◽  
Infrared Radiation ◽  
Design Methodology ◽  
Main Rotor ◽  
Content Type ◽  
Exhaust Plume ◽  
Ir Signature ◽  
Plume Flow ◽  
The Impact ◽  
Rotational Direction

Purpose This study aims to investigate the effects of exhaust direction on exhaust plume and helicopter infrared radiation in hover and cruise status. Design/methodology/approach Four exhaust modes are concerned, and the external flow field and fuselage temperature field are calculated by numerical simulation. The infrared radiation intensity distributions of the four models in hovering and cruising states are computed by the ray-tracing method. Findings Under the hover status, the exhaust plume is deflected to flow downward after it exhausts from the nozzle exit, upon the impact of the main-rotor downwash. Besides, the exhaust plume shows a “swirling” movement following the main-rotor rotational direction. The forward-flight flow helps prevent the hot exhaust plume from a collision with the helicopter fuselage generally for the cruise status. In general, the oblique-upward exhaust mode provides moderate infrared radiation intensities in all of the viewing directions, either under the hover or the cruise status. Compared with the hover status, the infrared radiation intensity distribution alters somewhat in cruise. Originality/value Illustrating the influences of exhaust direction on plume flow and helicopter infrared radiation and the differences of helicopter infrared radiation under hover and cruise statuses are identified. Finally, an appropriate exhaust mode is proposed to provide a better IR signature distribution.

scholarly journals Transmittance and Radiance Computations for Rocket Engine Plume Environments

2003 ◽  
Author(s):  
Gopal D. Tejwani
Keyword(s):  
Molecular Species ◽  
Space Shuttle ◽  
Rocket Engine ◽  
Line Of Sight ◽  
Layer By Layer ◽  
Atmospheric Conditions ◽  
Combustion Gas ◽  
Exhaust Plume ◽  
Temperature And Pressure ◽  
High Degree

Rocket engine exhaust plume is generally thermal in character arising from changes in the internal energy of constituent molecules. Radiation from the plume is attenuated in its passage through the atmosphere. In the visible and the infrared region of the spectrum for clear-sky conditions, this is caused mainly through absorption by atmospheric molecular species. The most important combustion-product molecules giving rise to emission in the IR are water vapor, carbon dioxide, and carbon monoxide. In addition, the high temperature plume reacting with the surrounding atmosphere may produce nitrogen oxides, in the boundary layer, all of which are strongly emitting molecules. Important absorbing species in the atmosphere in the engine plume environment are H2O, CO, CO2, CH4, N2O, NO, and NO2. Under normal atmospheric conditions, the concentrations of O3, SO2, and NH3 are too small to produce any significant absorption. Essentially the problem comprises of the propagation of radiation from a hot gas source through a long cool absorbing atmosphere thus combining aspects of atmospheric and combustion gas methods. Since many of the same molecular species are responsible for both emission and absorption, the high degree of line position correlation between the emission and absorption spectra precludes the decoupling of the optical path into isolated emitter and absorber regions and multiplying the source band radiance by the absorber band transmittance in order to arrive at the transmitted radiance spectrum. Also, very strong thermal gradients may be encountered. All this suggests that a layer-by-layer computation is called for. The pathlength through the plume and the atmosphere is assumed to go through a certain number of layers, each of which is considered to have all molecular species in local thermodynamic equilibrium at constant temperature and pressure within the layer. Radiative transfer problems can be visualized as a set of parallel layers orthogonal to the line of sight, each with an input radiance from the previous layer and an output radiance to the subsequent layer. The MODTRAN (MODerate resolution TRANsmission) code is ideally suited for layer-by-layer absorption/emission calculations for atmospheric molecular species. We have utilized MODTRAN 4.0 computer code, implemented on a Power Mac G3, for the radiance and transmittance computations. The MODTRAN code has been adapted for the engine plume radiance computations. If the plume composition and flowfield parameters such as the temperature and pressure values are known along the line of sight by means of the experimental measurements or (more likely) CFD simulations, one can compute the radiance from any plume with high degree of accuracy at any desired point in space. Emission and absorption characteristics of several atmospheric and combustion species have been studied and presented in this paper with reference to the rocket engine plume environments at the Stennis Space Center. In general transmittance losses can not be neglected for any pathlength of 2 m or more. We have also studied the effect of clouds, rain, and fog on the plume radiance/transmittance. The transmittance losses are severe if any of these occur along the line of sight. Preliminary results for the radiance from the exhaust plume of the space shuttle main engine are shown and discussed.

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