Combustion process, Other Engineering

Combustion process:

Air from the engine compressor enters the combustion chamber at a velocity up to 500 feet per second, but because at this velocity the air speed is far too high for combustion, the first thing that the chamber must do is to diffuse it, i.e. decelerate it and raise its static pressure. Because the speed of burning kerosene at normal mixture ratios is only a few feet per second, any fuel lit even in the diffused air stream, which now has a velocity of about 80 feet per second, would be blown away. A region of low axial velocity has therefore to be created in the chamber, so that the flame will remain alight throughout the range of engine operating conditions.

In normal operation, the overall air/fuel ratio of a combustion chamber can vary between 45:1 and 130:1. Kerosene, however, will only burn efficiently at, or close to, a ratio of 15:1, so the fuel must be burned with only part of the air entering the chamber, in what is called a primary combustion zone. This is achieved by means of a flame tube (combustion liner) that has various devices for metering the airflow distribution along the chamber.

 

834_combustion proces.png

Approximately 20 per cent of the air mass flow is taken in by the snout or entry section. Immediately downstream of the snout are swirl vanes and a perforated flare, through which air passes into the primary combustion zone. The swirling air induces a flow upstream of the centre of the flame tube and promotes the desired recirculation. The air not picked up by the snout flows into the annular space between the flame tube and the air casing.

Through the wall of the flame tube body, adjacent to the combustion zone, are a selected number of holes through which a further 20 per cent of the main flow of air passes into the primary zone. The air from the swirl vanes and that from the primary air holes interacts and creates a region of low velocity recirculation. This takes the form of a toroidal vortex similar to a smoke ring, and has the effect of stabilising and anchoring the flame. The recirculating gases hasten the burning of freshly injected fuel droplets by rapidly bringing them to ignition temperature.

Posted Date: 9/11/2012 9:31:35 AM | Location : United States







Related Discussions:- Combustion process, Assignment Help, Ask Question on Combustion process, Get Answer, Expert's Help, Combustion process Discussions

Write discussion on Combustion process
Your posts are moderated
Related Questions
flag manipulation instruction

1) An investment project requires a net investment of $100,000. The project is expected to generate annual net cash flows of $28,000 for the next 5 years. The firm''''s cost of cap

HOW WOULD YOU JUDGE THE POTENTIAL PROFIT OF BAJAJ ELECTRONICS ON THE FIRST YEAR OF SALES TO BOOTH PLASTICS AND GIVE YOUR VIEWS TO INCREASE THE PROFIT?

Fire prevention - fire risk assessment: Fire prevention measures include: Reducing the combustible materials, Reducing the risk of ignition, Reducing

Calculatethe tax disadvantage to organizing a U.S. business today, after passage of the Jobs and growth Tax relief reconciliation act of 2003, as a corporation versus a partnership

Q. What are the secondary operations we apply in powder metallurgy methods. Give their use also. Ans. Secondary Processes of Manufacture : In addition to the basic proce

Say that a buyer of bonds values good bonds at $500 and values bad bonds at $250. Sellers of both good and bad bonds value them at $350. If the fraction of good sellers and bad s

hysteresis loss least epends on

the real risk free rate of interest is 3 percent. Inflation is expected to be 3 percent for 2 years. What is nominal rate of interest for the 2 years bond?

INVALIDATION OF CERTIFICATE OF AIRWORTHINESS Listed below are the four major reasons why a Certificate of Airworthiness could become invalid. There may be other specific reason