In a gas turbine engine, turbine section
- temperature decreases along with pressure and velocity.
- velocity decreases and pressure increases.
- velocity increases and pressure decreases.
Explanation
In the turbine section the gas expands through convergent nozzle passages, so its velocity increases while pressure falls and energy is extracted to drive the compressor. This expansion, with rising velocity and falling pressure, is the opposite of the compression process in the compressor.
deri asking:
Debate: Does velocity (dynamic pressure) drop across the whole turbine section? Obviously V increases as it passes through the nozzle guide vanes (convergent) but after passing through each turbine stage the velocity overall will decrease.?
Community Comments (2)
J
JD2016 Posts: 54 21.03.2017 / 22:53
This probably needs clarification. DERI is right - the velocity increases locally as the gas passes through the nozzle and decreases as it passes across the turbine blade. It then increases velocity in the next stage nozzle followed by a decrease. Overall though, the velocity increases across the turbine section. Have a look at Fig 2-5-1 on page 15 of the RR Jet Engine book.
It shows a 3 stage turbine. The green line on the graph is velocity and at the inlet to the first stage turbine, the velocity is just UNDER 500ft/sec. At the outlet of the third stage, the velocity is OVER 500ft/sec. Pressure at inlet to first stage is approx 137 psi and at outlet from 3rd stage is about 37 psi - a good 100 psi reduction.
It shows a 3 stage turbine. The green line on the graph is velocity and at the inlet to the first stage turbine, the velocity is just UNDER 500ft/sec. At the outlet of the third stage, the velocity is OVER 500ft/sec. Pressure at inlet to first stage is approx 137 psi and at outlet from 3rd stage is about 37 psi - a good 100 psi reduction.
A
avionics Posts: 9 23.03.2017 / 04:30
please do not forget that the design of the turbine section area is a wholly a divergent per se
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