申論題

1. (25%) The jet pump injects water at U₁=40 n/s through a 7.5-cm-pipe and entrains a secondary flow of water U₂=3 m/s in the annular region around the small pipe. The two flows become fully mixed downstream, where U₃ is approximately constant. Let p₁and p₂ =172.4 kPa, and the distance between sections 1 and 3 is 2.032 m. The average wall shear stress between sections 1 and 3 is 335 Pa. Assume that the flow is steady and incompressible. For water, take ρ=998 kg/m³.