Exhaust jet mixing - aircraft design, Other Engineering

Exhaust Jet Mixing:

Figure shows that the noise from the exhaust jet is the main contributor to the total noise generated by a low by-pass ratio turbo-fan. For a turbo-jet the noise from the exhaust is an even greater contributor to the whole. Fortunately it is comparatively easy to reduce the noise by increasing the mixture rate of the exhaust gases with the atmosphere. This can be achieved by increasing the contact area of the atmosphere with the gas stream by incorporating a corrugated or lobe-type suppresser in the propelling nozzle.

The addition of a corrugate nozzle gives the effect shown in figure 7.16. In the corrugated nozzle, atmospheric air flows down the outside corrugations and into the exhaust jet to promote rapid mixing. In the lobe-type nozzle, the exhaust gases are divided to flow through the lobes and a small central nozzle. This forms a number of separate exhaust jets which rapidly mix with the air entrained by the suppresser lobes. Deep corrugations or lobes give a greater noise reduction, but the penalties incurred limit the size of the suppressers, eg. to achieve the required nozzle area, the overall diameter of the suppresser may have to be so large that excessive drag results.

A nozzle may be designed to give a large reduction in noise level, but this could incur a considerable weight penalty due to the additional strengthening required. A compromise that gives a noticeable reduction in noise level with the minimum sacrifice of engine thrust or increase in weight is, therefore, the designer's aim.

 

 

1979_Exhaust Jet Mixing.png

Posted Date: 9/12/2012 2:08:05 AM | Location : United States







Related Discussions:- Exhaust jet mixing - aircraft design, Assignment Help, Ask Question on Exhaust jet mixing - aircraft design, Get Answer, Expert's Help, Exhaust jet mixing - aircraft design Discussions

Write discussion on Exhaust jet mixing - aircraft design
Your posts are moderated
Related Questions
software development cycle for 8086

PROPELLER TORQUE Propeller torque is produced by the aerodynamic drag on the blades when in motion. Propeller torque acts in the plane of rotation and opposes engine torque.

FLUID (LIQUID) ICE PROTECTION SYSTEMS: Liquid ice protection systems can be used as either anti-ice or de-ice systems.  The system is designed to project a film or fluid over t

main() { int i; i=i+2*i++; printf("%d",i); }

Derive an expression for electron concentration in conduction band and hole concentration in valance band

We will need to use several different flow models as we go along. It is crucial to understand the simplifications used to obtain these models because these limit the validity of th

Process of fire risk assessment: In the UK, the process for  the FRA came out of the process for a general risk assessment. In a general risk assessment hazards are identif


ceramics under heat

Allowances for pattern : A pattern is always made larger than the required size of the casting in order to allow for various factor, such as shrinkage, machining, distortion and r