Combustion Chambers Questions and Answers

Answer: A

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason explains the first. When every design exceeds 99 per cent, the differences between them lie in the last fraction of a per cent and are within the scatter of measurement, so the parameter cannot rank them. Development effort therefore concentrates on pressure loss, pattern factor, stability and emissions, where real differences remain.

Answer: B

Correct answer: 1 and 2 only

Statements 1 and 2 describe the two zones correctly. Statement 3 confuses the local mixture with the overall one: the primary zone is near stoichiometric, but the chamber as a whole runs at about 60 to 1, roughly four times leaner than a flame can sustain. The zoning of the air is precisely what reconciles the two.

Answer: C

Correct answer: 1 and 2 only

Statements 1 and 2 describe the two opposing trends correctly. Statement 3 contradicts them - since nitrogen oxides rise with power while carbon monoxide and hydrocarbons fall, no single condition minimises all of them, which is why emissions are certified over a defined landing and take-off cycle rather than at one point.

Answer: D

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: annular chambers are the shortest and lightest, and can chambers the easiest to develop because a single tube can be tested alone. Statement 3 is wrong - the continuous annulus gives the most uniform exit temperature, not the poorest, which is one of the reasons it is preferred.

Answer: A

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: three to six per cent pressure loss is typical, and pattern factor governs turbine blade life through the temperature the hottest blade sees. Statement 3 is wrong for the reason the topic returns to repeatedly - every serious design exceeds 99 per cent at cruise, so the parameter discriminates between none of them.

Answer: B

The four regions are encountered in the order listed and each solves a different problem. The last is upstream of the flame tube entirely, which is why it is easily forgotten when the chamber is described by its zones alone.

Answer: C

Correct answer: A-1, B-2, C-3, D-4

Four emissions from four distinct mechanisms. Nitrogen oxides form thermally at the high flame temperature of the primary zone. Carbon monoxide is the product of oxidation that did not go to completion, which happens at low power. Smoke is soot formed in locally rich pockets. And unburnt hydrocarbons are fuel that escaped combustion altogether, worst at idle.

Answer: D

Correct answer: A-1, B-2, C-3, D-4

Four components with four purposes. The swirler creates the recirculation that anchors the flame. The dilution holes set the exit temperature and its pattern, which is why they are the ones moved during development. Effusion holes protect the wall using far less air than older slots. And the igniter starts combustion at light-up and at relight.

Answer: A

Correct answer: A-1, B-2, C-3, D-4

Each parameter has a consequence outside the chamber. Combustion efficiency shows up as fuel consumption. Pressure loss is total pressure the turbine never sees, so it costs thrust. Pattern factor sets turbine blade life through the hottest blade. And the weak extinction limit sets how rapidly the engine may be decelerated without the flame going out.

Answer: B

Correct answer: The diffuser

The flame tube has three zones - primary, intermediate and dilution - each with its own air supply and its own job. The diffuser sits upstream of the flame tube altogether, slowing the compressor delivery air before it arrives, and is a separate component rather than a zone within the tube.