10.1 Name TWO types of reaction turbines - NSC Mechanical Technology Fitting and Machining - Question 10 - 2018 - Paper 1

The impulse turbine operates by changing the velocity of a water jet.

• The jet flows onto the turbine's curved blades, altering the flow direction and generating a force.
• As the turbine spins, the momentum of the water provides the force, causing a rotation.
• Prior to contact with the blades, the water's pressure is converted to kinetic energy through a nozzle.
• Importantly, there is no pressure drop at the turbine blades, ensuring an efficient operation.

Controlling the speed of a steam turbine is crucial to prevent the rotor from achieving an uncontrollable speed, which may lead to mechanical failure or an accident.

• Speed regulation ensures optimal performance and safety of the turbine.

Three advantages of a gas turbine include:

1. Smooth operation due to the absence of reciprocating parts, which reduces vibrations and wear.
2. Greater fuel efficiency, as it can use various fuels effectively.
3. Less maintenance needed over time due to fewer moving parts compared to traditional engines.

The waste gate serves to divert exhaust gases away from the turbine wheel, regulating boost pressure.

• This ensures that the turbocharger operates efficiently without over-boosting the engine.

At high altitude, the performance of a motor vehicle engine decreases due to reduced air density.

• This leads to less oxygen available for combustion, resulting in lower power output.

One advantage of a turbocharger over a supercharger is that a turbocharger is powered by exhaust gases, which means it does not draw power from the engine crankshaft.

• This enhances overall efficiency as it utilizes otherwise wasted energy.

The type of blower depicted in FIGURE 10.8 is a Roots blower, which is commonly utilized as a supercharger in internal combustion engines.