# Question 7.18: It is proposed to use high pressure water in the design of a...

It is proposed to use high pressure water in the design of a power unit for a rotary cleaning brush. As sketched in Figure 7.30, water enters the inlet of the power unit and exits through N jets. If friction in the inlet bearing and aerodynamic drag are negligible, what is the torque available to rotate the brush at a given angular velocity? How many jets should be employed?

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Question: 7.17

## Water ﬂows steadily at 3 m/s through the vertical offset pipe bend shown in Figure 7.29. The pipe diameter is 10 cm, the upstream gage pressure is 275 kPa, and the pressure drop through the bend is estimated to be 50 kPa. Find the forces that must be exerted by each ﬂange on the pipe bend to keep ...

We are asked to determine the forces applied to an...
Question: 7.16

## A small air compressor is running steadily at an inlet ﬂowrate of Q1 = 4 ft³/min. The inlet conditions for the air are p1 = 14.7 psia, T1 = 70°F, A1 = 2 in.²; and the outlet conditions are p2 = 100 psig = 114.7 psia, T2 = 200°F, A2 = 0.05 in.². If the power required to run the compressor is 2 hp, ...

We must determine the heat transfer rate for a com...
Question: 7.15

## A water pump runs steadily at a ﬂowrate of Q = 80 gal/min with a pressure rise of Δp = 40 psi. The inlet and outlet areas are the same. (1) Determine the minimum power input necessary to run the pump assuming an ideal pumping process. You may assume that this ideal process involves no heat transfer ...

This problem is concerned with the power input to ...
Question: 7.13

## An insulated air tank, initially at a pressure of 0 MPa (gage) and 20°C, is connected by a valve to an air supply that provides air at a constant pressure of 0.5 MPa (gage) and the same temperature. When the valve is opened, the initial mass ﬂowrate into the tank is found to be ...

We are asked to determine the initial rate of chan...
Question: 7.14

## Use an energy balance to analyze the steady, fully developed ﬂow of constant density ﬂuid in a round pipe shown in Figure 7.26. Consider laminar and turbulent ﬂow, and assume that the internal energy and pressure are uniform on any cross section of the pipe. ...

As discussed in Example 7.7, the laminar ﬂow veloc...
Question: 7.12

## Water is pumped steadily through a 90° reducing elbow welded onto the end of a pipe and exits to the atmosphere as shown in Figure 7.21A. What is the force applied to the elbow at the weld joint? Assume uniform conditions at the elbow inlet and exit and neglect gravity. ...

We are asked for the structural force applied to t...
Question: 7.11

## What is the horizontal force required to hold the thin sluice gate of height H and length L in the position shown in Figure 7.20A? You may assume 2D steady ﬂow under the gate, with uniform velocities and hydrostatic pressure distributions at the indicated locations. What is the horizontal ...

This question asks for the horizontal component of...
Question: 7.10

## A liquid-fueled rocket is in steady operation on a test stand at sea level as shown in Figure 7.18A. What is the force acting on the support pylon at the rocket attachment point? What is the thrust produced by the rocket? Assume the velocity, pressure, and temperature of the exhaust ...

Figure 7.18A shows the physical arrangement, and F...
Question: 7.8