L16_Efficiency_Implications

L16_Efficiency_Implications - Figure 1 shows a propeller...

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For fighter aircraft that need high thrust/weight and fly at high speed, it is typical to employ engines with smaller inlet areas and higher thrust per unit mass flow, The small inlet of one of the F-22 Raptor's two engines is visible just below the cockpit . The F-22 Raptor (Copyright 1999 by Lockheed Martin). However, transport aircraft that require higher efficiency and fly at lower speeds usually employ engines with relatively larger inlet areas and lower thrust per unit mass flow, The large inlets of a Boeing 777-200's engines are shown below. The Boeing 777-200
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At low flight velocities, the highest propulsive efficiency is typically obtained with a propeller or an unducted fan.
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Unformatted text preview: Figure 1 shows a propeller craft, and Figure 2 shows a sketch of a jet engine with an unducted fan. Figure 3 shows propulsive efficiency as a function of airspeed for different engine bypass ratios. Figure 1: A propeller gives a relatively small impulse ( ) to a relatively large mass flow (Boeing, 2000) Figure 1 2 : An advanced, contour-rotating, unducted fan concept (Rolls-Royce, 1992) Figure 3 : Propulsive efficiency comparison for various gas turbine engine configurations (Rolls-Royce, 1992)...
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This note was uploaded on 04/11/2008 for the course AEM 4203 taught by Professor Schwartzentruber during the Spring '08 term at Minnesota.

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L16_Efficiency_Implications - Figure 1 shows a propeller...

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