In impulse turbines, the working medium has the same static pressure in front of and behind the rotor. The conversion of pressure energy into kinetic energy takes place in the fixed nozzles of the distributor, not at the turbine rotor. This compressed-air driven experimental unit can be used to understand turbines powered by steam or water.
The is a single-stage, axial impulse turbine. The turbine consists of a rotor that is installed inside a transparent housing, a distributor with four nozzles and a band brake for applying a load to the turbine. The number of active nozzles can be adjusted by means of the valves. The compressed air velocity is increased in the nozzles. The air flow that hits the blades generates an impulse that causes the rotor to start moving.
The inlet and outlet pressure at the turbine are indicated on manometers. The turbine torque is determined by measuring the force on the band brake. The speed is measured with an optical speed sensor. Torque, speed and temperatures are digitally displayed. The air flow rate is measured with a rotameter and set by means of a valve.
The turbine is fitted with a solenoid valve as a safety device in case of overspeed. The brake drum on the turbine shaft is cooled by the compressed air.
The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.
Learning Objectives / Experiments
Design and function of an impulse turbine
Determination of torque, power and efficiency
Graphical representation of characteristic curves for torque, power and efficiency
Investigation of the effect of nozzle pressure and number of nozzles
Specification
Investigation of a compressed air driven axial impulse turbine
Transparent front panel for observing the operating area
Distributor with 4 nozzles
Selectable number of nozzles
Applying a load to the turbine by using the band brake
Setting the primary pressure with the pressure reducing valve
Valve and flow meter for setting the flow rate
Solenoid valve as a safety device to prevent overspeed
Determination of the torque on the turbine shaft using a force sensor
Measurement of the turbine speed with an optical speed sensor
Manometer for displaying pressures on the inlet and outlet side