Turbins assginmen
Review Questions:
1. Why does the state-line-end-point (SLEP) vary with changes in turbine load? What do these changes represent?
A. The position of the SLEP will vary with different loads to represent the decreased efficiency at loads away from max turbine efficiency.
2. Why do most propulsion turbines use multiple control valves instead of a single throttle valve?
A. The multiple control valves allow for a less energy loss than using the throttle valve.
3. How are control valves adjusted to obtain a smooth linear response over the turbine operating range when using a bar-lift operating mechanism?
A. The stems of the various nozzle disks are at different lengths in order have different lengths in order to make turbine operation linear.
4. How do bypass valves increase the efficient operating range of a turbine?
A. Bypassing the first stage, Curtis wheel, and going into the Rateau stages that are more efficient but less power improves efficiency.
5. How does the operation of an additional cruising turbine improve overall propulsion turbine efficiency at low speed?
A. The cruising turbine adds more stages at low power to reduce nozzle exit velocity and improve efficiency.
6. What is the function of the astern guarding valve?
A. Prevents steam leakage into astern elements during ahead operation.
7. Why are rate limiters incorporated in some throttle control systems to regulate the rate at which the throttle valve opens or closes?
A. The rate limiter minimizes pressure excursions while maneuvering. Allowing the boiler to keep up with the changes and not using up too much steam.
8. Identify the safety features, which may be incorporated into an electro-hydraulic propulsion control system. Describe the function of each.
A. Overspeed; Low boiler pressure; Boiler drum level; Turbine vibrations; in the event of one of the alarms the throttle would either cut the speed or slow it down.
9. What is the function of a backpressure trip on
1. Why does the state-line-end-point (SLEP) vary with changes in turbine load? What do these changes represent?
A. The position of the SLEP will vary with different loads to represent the decreased efficiency at loads away from max turbine efficiency.
2. Why do most propulsion turbines use multiple control valves instead of a single throttle valve?
A. The multiple control valves allow for a less energy loss than using the throttle valve.
3. How are control valves adjusted to obtain a smooth linear response over the turbine operating range when using a bar-lift operating mechanism?
A. The stems of the various nozzle disks are at different lengths in order have different lengths in order to make turbine operation linear.
4. How do bypass valves increase the efficient operating range of a turbine?
A. Bypassing the first stage, Curtis wheel, and going into the Rateau stages that are more efficient but less power improves efficiency.
5. How does the operation of an additional cruising turbine improve overall propulsion turbine efficiency at low speed?
A. The cruising turbine adds more stages at low power to reduce nozzle exit velocity and improve efficiency.
6. What is the function of the astern guarding valve?
A. Prevents steam leakage into astern elements during ahead operation.
7. Why are rate limiters incorporated in some throttle control systems to regulate the rate at which the throttle valve opens or closes?
A. The rate limiter minimizes pressure excursions while maneuvering. Allowing the boiler to keep up with the changes and not using up too much steam.
8. Identify the safety features, which may be incorporated into an electro-hydraulic propulsion control system. Describe the function of each.
A. Overspeed; Low boiler pressure; Boiler drum level; Turbine vibrations; in the event of one of the alarms the throttle would either cut the speed or slow it down.
9. What is the function of a backpressure trip on