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Supersonic Aircraft Impact on Environment

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Supersonic Civil Aircraft Impact on Environment

Tech Area / Field

  • ENV-APC/Air Pollution and Control/Environment
  • ENV-MIN/Monitoring and Instrumentation/Environment
  • SAT-AER/Aeronautics/Space, Aircraft and Surface Transportation

Status
8 Project completed

Registration date
03.07.2001

Completion date
10.10.2006

Senior Project Manager
Tyurin I A

Leading Institute
Central Aerodynamic Institute, Russia, Moscow reg., Zhukovsky

Project summary

Further development of supersonic civil transports calls for solutions to a number of ecology problems, of which the more important will be considered here:
- community noise;
- sonic boom;
- air pollution.
Task А. Community noise reduction.
The engine jets are the main source of the noise produced by SST-2. Only one logical solution suggests itself: a combination of noise suppressing techniques with simultaneous optimization of all the vital aircraft parameters. Noise suppressing nozzle (NSN) is a crucial component of the foregoing system since it is mainly the jet that produces noise. A multicomponent NSN with lobes or iris jet nozzle and ejector whose inner surface is coated with sound absorbers appears the most feasible among all the NSNs so far considered. Besides a study into the SST-2 nozzle, we are going to analyse aeroacoustic jets issuing from noise suppressors of various layouts to conclude on their acoustic efficiency and expediency for the SST-2 engines.
Task В. A stusy into the effect of atmospheric condition on the sonic boom. The sonic boom minimization.
The sonic booms produced by supersonic aircraft, SST-2 in particular, are among the most serious environmental impacts. There are essential differences in the experimental (obtained from supersonic flight tests) and theoretical values of the sonic boom levels. The task is to find correlation between probabilistic characteristics of the sonic boom and the turbulent atmosphere parameters. The secondary booms are of much current interest for they propagate much further than the primary sonic boom audibility areas. There is a set of algorithms and programs for computation of the secondary sonic boom, however they all have sufficient disadvantages and require their following development. SST-2 and business supersonic airplane will need a special navigation system to analyze current atmospheric status. It appears that we should make it our first step to develop the onboard computer software for calculation of the sonic boom with regard for the weather conditions along the route and in the vicinity of the flight path. The sonic boom propagation beneath the sea surface make us think of its impact on the sea animals. Being insufficiently explored these issues call for development of methods and programs to calculate the sonic boom diagram deformation as a function of sea depth.
Task С. SST-2 atmospheric impact.
Consideration of the supersonic aviation environmental effects, such as physics-chemical impact of the exhaust jets on the clouds, their formation, ozone layer and upper atmosphere requires comprehension of the nature of vortex jets left by aircraft. Further studies (involving jet washing, jet-tip vortex interaction, modeling for the condensate droplet coagulation rate, heterogeneous processes of the engine-blown solid particles or those formed through condensation and coagulation, effects of aerosol electrification on particles coagulation in the air) are quite necessary for adequate quantitative modeling of aircraft wake in its vortex phase and its impact on the upper atmosphere. Moreover without a profound investigation we cannot make recommendations on the vortex wake control and minimize its harmful environmental effect. Besides methods employed today to determine the jet gas concentrations required the following development, Now we propose studying properties of vortex jets left by subsonic and supersonic aircraft both under and above the tropopause in different environments.Besides, we propose development of a database on the Russian air traffic existing now and anticipated in a while, specification of the space-time tropopause model over Russia and search for reasonable flight routes to minimize harmful environmental impact.

Expected Results


During the course of studying fundamental and applied problems of the Project it is expected to obtain a more complete knowledge on fundamental aspects of acoustic and aerodynamic phenomena attending the appearance of aircraft community noise, sonic boom and impact on atmosphere as well as knowledge which is necessary for determination of means helping to reduce environmental impact of advanced air vehicles.
Task A. Community noise reduction
New schemes of axisymmetrical and plane nozzles with noise suppression and a new method of organizing the main jet separation into a series of small jets will be proposed for accelerating the flow mixing in ejector. Thrust characteristics of nozzles with new schemes of noise suppression will be determined. A universal software for computer (mathematical model of nozzle) will be developed. Complete prediction models describing the processes of noise generation by supersonic jets of complex geometry will be developed and built. Nozzle models simulating all the essential features of real nozzle geometry will be fabricated and these models will be tested on the stand with a heated jet and in the anechoic chamber with an isothermal jet in the co-current flow. Noise spectra will be measured during the tests in different directions and different planes for the nozzle models nonsymmetrical relative to the axis. New ways of jet noise reduction with the help of soundabsorbing structures (SAS) in the ejector duct will be developed which will allow obtaining essential noise reduction in the frequency range determining the aircraft community noisiness.
Task B. Studies of atmosphere conditions influences on sonic boom and possibilities of its reduction.

Critical research about weather conditions effect on sonic boom will be produced. Establishment of relationships between parameters of probabilistic sonic boom amplitude and time-rise distributions and turbulence characteristics for isotropic model of turbulent atmosphere will be done. Mathematical model for calculating sonic boom propagation through singular points (return points, jumps of atmospheric parameters etc Diagrams for estimating influences of various aircraft and flight parameters at aircraft flight Mach numbers including low supersonic values will be created. Development of high speed code for airborne computer allowing for calculating sonic boom influence regions in a real time scale on the base of the weather data along and around the flight path. Developing the method for prediction of sonic boom signature deformation due to underwater penetration and propagation.


Task С. SST-2 atmospheric impact.
During experimental studies the possibility of mixing enhancement of two parallel co-flowing jets with the help of longitudinal vortices artificially created in external flow near nozzles will be evaluated. Visualization and determination of averaged and pulsating characteristics of jet-vortex mixing will be performed experimentally and possibility and effectiveness of jet-vortex mixing control methods will be evaluated as well. New models of nucleation and water vapor condensation will be formulated as well as the models for the growth of metastable droplets because of their collisions due to fluctuations of air flow behind an aircraft. The dependence of effective surfaces of porous particles on the gas properties, porosity and other properties of particles and characteristics of reaction will be determined for various physical and chemical heterogeneous processes (condensation/evaporation, chemical reactions of various order) by the theoretical and numerical investigations. Also the estimation of aerosol particles charging in aircraft trail on its coagulation will be done. The recommendations will be formulated on using of the most suitable method for the chemical composition measurement of the airplane wake. The data base will be created for existing and advanced aircraft flying above Russia. The analysis will be done for aircraft wake creation in various air paths (Mach number, flight altitudes, tropopause altitude, etc.). The aircraft paths will be drawn that minimize harmful influence on the atmosphere.
Meeting ISTC Goals and Objectives. Commercial meaning
The Project completely corresponds to ISTC goals since the given elaboration: supports fundamental and applied research in the field of environment protection; assists to solve national and international technical problems related with creation of ecologically pure air vehicles. the result of this Project possesses the commercial potential and, therefore, undoubtedly assists to the transition to market economics. directly uses fundamental scientific potential and experience of TsAGI research groups which were previously employed in scientific military programs and thus provides alternative activity for highly qualified specialists and assists to incorporate them to international scientific community.

Role of Foreign Collaborators:
It is expected the following participation of collaborators: information exchange during the Project execution; analysis of results obtained during the Project execution; the assistance in the estimation of possibilities of commercial use of Project results; conducting of joint symposia and workshops.

Technical Approach and Methodology:
The tasks of the Project are grouped into 3 Tasks. The main methodological directions during the solving of each problem are: analysis of the problem; construction of theoretical or/and computational model of the process and computer code creation; elaboration of experimental program, method and instrumentation, data storage by numerical or/and physical experiment. By the specificity of solving problems the relationship between theoretical and experimental approaches to research and elaboration differs at different directions.


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