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The slightly kinked diagonal line on the main part of the map is known as the surge (or stall) line. Above this line is a region of unstable flow, which is an area best avoided. A compressor surge or compressor stall causes an abrupt reversal of airflow in the compressor. Compressor blades create a pumping action by working as airfoils.
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.
For example, if the static compression ratio is 10:1, and the dynamic compression ratio is 7.5:1, a useful value for cylinder pressure would be 7.5 1.3 × atmospheric pressure, or 13.7 bar (relative to atmospheric pressure). The two corrections for dynamic compression ratio affect cylinder pressure in opposite directions, but not in equal strength.
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.
Sketch of multiphase flow in an oil pipe, where the continuous phase is the liquid (blue) carrying smaller particles. Gas (white) and oil particles (black) are in a disperse phase. In fluid mechanics , multiphase flow is the simultaneous flow of materials with two or more thermodynamic phases . [ 1 ]
In fluid dynamics, the Buckley–Leverett equation is a conservation equation used to model two-phase flow in porous media. [1] The Buckley–Leverett equation or the Buckley–Leverett displacement describes an immiscible displacement process, such as the displacement of oil by water, in a one-dimensional or quasi-one-dimensional reservoir.
Different modes of two-phase flows. In fluid mechanics, two-phase flow is a flow of gas and liquid — a particular example of multiphase flow.Two-phase flow can occur in various forms, such as flows transitioning from pure liquid to vapor as a result of external heating, separated flows, and dispersed two-phase flows where one phase is present in the form of particles, droplets, or bubbles in ...
The Pratt & Whitney TF30 used on the F-111 had a pressure ratio of about 20:1, while newer engines like the General Electric F110 and Pratt & Whitney F135 have improved this to about 30:1. An additional concern is weight. A higher compression ratio implies a heavier engine, which in turn costs fuel to carry around.