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When the compressor’s operation approaches the surge point the controller modulates either a flow control valve (FCV) in the recycle line or adjusts the speed (SC) of the compressor driver. The FCV allows cooled gas from the discharge to spill back to the suction of the compressor, thereby maintaining the forward flow of gas through the machine.
EGR valve the top of box on top of the inlet manifold of a Saab H engine in a 1987 Saab 90. In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide (NO x) emissions reduction technique used in petrol/gasoline, diesel engines and some hydrogen engines. [1]
The former makes the IP compressor surge line shallower, swinging it away from the shallow working line, thus improving IP compressor surge margin. At a given IP compressor pressure ratio, opening the blow-off valve forces the IP compressor entry corrected flow to increase, to a point where the IP compressor surge margin tends to be better.
The simplest inlet to a centrifugal compressor is typically a simple pipe. Depending upon its use/application inlets can be very complex. They may include other components such as an inlet throttle valve, a shrouded port, an annular duct (see Figure 1.1), a bifurcated duct, stationary guide vanes/airfoils used to straight or swirl flow (see Figure 1.1), movable guide vanes (used to vary pre ...
The normally closed valves will not permit flow from the inlet port of the valve to the outlet port, normally the flow will be permitted only by changing the position of the valve. In general, valves are designated as 2/2 DCV, 3/2 DCV, 5/2 DCV, 5/3 DCV etc., in which the first number indicates number of ports and second number indicates number ...
On civil turbofans, the first stage of the LP compressor is often a single-stage fan. If the HP compressor pressure ratio exceeds about 4.5:1, then the unit will probably have variable geometry (i.e. variable stators) on the first few stages, to make the surge line on the compressor map more shallow, to accommodate the shallow working line.
Compressor characteristic is a mathematical curve that shows the behaviour of a fluid going through a dynamic compressor.It shows changes in fluid pressure, temperature, entropy, flow rate etc.) with the compressor operating at different speeds.
The following explanation for surging refers to running a compressor at a constant speed on a rig and gradually reducing the exit area by closing a valve. What happens, i.e. crossing the surge line, is caused by the compressor trying to deliver air, still running at the same speed, to a higher exit pressure.