10.22 Experimental test data for an aircraft engine fuel pump are presented below. This gear pump is required to supply jet fuel at 450 pounds per hour and 150 psig to the engine fuel controller. Tests were conducted at 10, 96, and 100 percent of the rated pump speed of 4536 rpm. At each constant speed, the back pressure on the pump was set, and the flow rate was measured. On one graph, plot curves of pressure versus delivery at the three constant speeds. Estimate the pump displacement volume per revolution. Calculate the volumetric efficiency at each test point and sketch contours of constant ηυ. Evaluate the energy loss caused by valve throttling at 100 percent speed and full delivery to the engine.

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Pump Back Fuel Fuel Pump Back Fuel Pump Back Fuel Speed Pressure Flow Speed Pressure Flow Speed Pressure Flow (rpm) (psig) (pph) (rpm) (psig) (pph) (rpm) (psig) (pph) 200 1810 200 1730 200 89 4536 (100%) 400 300 1810 4355 300 1750 453 250 73 1810 (96%) 400 1735 (10%) 300 58.5 500 1790 500 1720 350 45 900 1720 900 1635 400 30 * Fuel flow rate measured in pounds per hour (pph).