1.

Segment V12.1: Windmills
(Related to Textbook Section 12.2 - Basic Energy Considerations)

Windmills are unducted, axial-flow turbomachines that extract energy from the moving air.

The windmill blades are shaped so that the absolute velocity of the air upstream of the windmill is different than that downstream. For this to occur, the blades must push on the air (or equal and opposite, the air must push on the blades), thereby producing a torque. Although the child's pin-wheel, the farm windmill, and the modern wind turbine are quite different in details, size, and purpose, their basic operating principles are the same.

2.

Segment V12.2: Self-Propelled Lawn Sprinkler
(Related to Textbook Section 12.3 - Basic Angular Momentum Considerations)

Turbomachine shaft work can be calculated from the moment-of-momentum equation which expresses the relationship between angular momentum of a fluid about an axis of rotation and torque.

Although water enters the lawn sprinkler in the axial direction with zero angular momentum about the axis of rotation, the water exits with angular momentum about that axis (the exiting jets are not in the radial direction). The sprinkler arm, which is connected to the drive wheels through a set of gears, does not rotate until the flowrate is increased to provide sufficient torque. Some of the torque is used to power the sprinkler across the yard. The device is a turbine.

3.

Segment V12.3: Windshield Washer Pump
(Related to Textbook Section 12.4 - The Centrifugal Pump)

For each revolution or cycle of a positive displacement pump, a given amount of fluid is pumped. Except for leakage, the volume flowrate is independent of the operating pressure differential.

Although the impeller for a windshield washer pump looks like that for a centrifugal pump (a turbomachine), it is a positive displacement pump. The shaft of the flexibleblade impeller is off-set from the center of the chamber in which it is housed. As the impeller rotates, each blade deforms, causing the fluid to alternately enter or leave the variable-volume cavity between successive impeller blades, thereby causing a pumping action.

4.

Segment V12.4: Pelton Wheel Lawn Sprinkler
(Related to Textbook Section 12.8.1 - Impulse Turbine)

A Pelton wheel is a simple type of impulse turbine which uses a jet (or jets) of water that is deflected by a series of buckets attached to the wheel.

The deflection causes a change in angular momentum of the fluid about the axis of rotation, resulting in a torque on the turbine wheel. The power output equals the torque times the angular velocity. Power generated by a small Pelton wheel in the sprinkler is used to drive the oscillating arm on the sprinkler. By using an appropriate set of gears and a cam, the desired oscillating motion is obtained.

5.

Segment V12.5: Dental Drill
(Related to Textbook Section 12.8.1 - Impulse Turbine)

In an impulse turbine, there is essentially no pressure drop across the turbine rotor. The pressure drop occurs in the nozzles just upstream of the rotor and produces the high speed jet that impinges upon the rotor.

A dental drill is driven by a small diameter, high speed impulse turbine. Because of the small diameter of the rotor, the angular velocity must be very large (i.e., 300,000 rpm) if the blade speed is to be of the same order as the air speed from the nozzles. Small, precision ball bearings and precise machining of the rotor are needed.