Lecture 9
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This document discusses several topics related to fluid mechanics including: 1. Airfoil theory explains how providing curvature to the bottom of a flat plate and a sharp edge at the end can increase the ratio of lift to drag force compared to a flat plate at an angle of attack. 2. Reciprocating pumps work by using the length and area of the piston stroke along with revolutions per minute to calculate discharge, with double acting pumps discharging twice as much water. 3. The difference between actual and theoretical discharge of a pump is known as slip, and pump performance is affected by factors like suction head, delivery head, and piston acceleration.
Lecture 9
- 1. Fluid Mechanics II Lecture 9 Muhammad Usman
- 2. Airfoil Theory • Angle of inclination depends on the geometerical position of the body with respect to motion. • Flat plate inclined at 4 the ratio of lift to drag force is about 6. To increase this ratio • The plate is given a slight curvature in its bottom • By nicely rounding off the front end of the plate • Providing sharpe edge in the end.
- 3. Reciprocating Pump • L=Length of the stroke • A= Cross sectional Area • N= No. Of revolutions per mint. • Discharge of Water= LAN/60. • Discarge of water for double acting pump.=2LAN/60.
- 4. Slip of Pump • The difference between actual and theoretical discharge is known as slip of the pump. • Force on the piston during suction stroke=wHsA • Force on the piston during delivery stroke= wHdA • Power= wQ(Hs+Hd)
- 6. Variation of Pressure In section and Delivery pipes due to acceleration of the piston
- 7. Effect of Acceleration on the Indicator Diagram
- 8. Example 1 • A single acting reciprocating pump has a plunger of diameter 300mm and stroke of 200 mm. If the speed of the pump is 30 r.p.m. and its delivers 6.5 litres/sec of water find the coefficient of discharge and the percentage slip of the pump.
- 9. Example 2 • A single acting reciprocating pump, having plunger diameter 125 mm and stroke length 300 mm is drawing water from a depth of 4 meters from the axis of the cylinder at 24 r.p.m The length and diameter of suction pipe is 9 meters and 75 mm respectively. Find the pressure head on the piston at the begining and end of the suction stroke, if the barometer reads 10.3 m of water.