1. Draft tube is also called_______
a) Straight divergent tube
b) Simple elbow tube
c) Thermal tube
d) Elbow tube with varying cross section
Explanation: Draft tube is one of the most commonly used in the Kaplan turbine. It works as an outlet at the Kaplan turbine. Draft tube is also called straight divergent tube.
2. A draft tube helps in converting kinetic energy into________
a) Electrical work
b) Mechanical work
c) Chemical work
d) Thermal work
Explanation: Turbine extracts energy and converts it into useful work. Turbine is a vortex related device. It means turbulence. Steam turbine converts energy into mechanical work by extracting thermal energy from pressurized steam.
3. Most common application of the draft tube is ______
a) Rotor
b) Motor
c) Pump
d) Filter
Explanation: Most common application of the draft tube is different types of pumps. It plays an important role in the putlet of the pump and the turbine.
4. Draft tube consists of conical diffuser with angles of______
a) 10 deg
b) 20 deg
c) 30 deg
d) 40 deg
Explanation: Draft tube consists of conical diffuser with angles of 10 degrees with respect to its position, Draft tubes are situated in the outlet of the turbine.
5. What is the purpose of a Draft tube?
a) To prevent flow separation
b) To avoid Pressure drag
c) To prevent rejection of heat
d) To increase efficiency
Explanation: Draft tube in a turbine and pumps helps to prevent flow separation in order to increase the turbine efficiency and increase its performance.
6.What is the maximum value of efficiency in a draft tube?
a) 100
b) 50
c) 90
d) 40
Explanation:The maximum value of efficiency in a draft tube is 90 percent. It cannot exceed more than 90 percent because of the heat losses due to flow of fluid.
7. The simple elbow draft tube is placed close to the_______
a) Head race
b) Tail race
c) Tank
d) Nozzle
Explanation: The simple elbow draft tube is placed close to the tail race. It consists of an extended elbow type tube. It is mainly used in the Kaplan turbine. It is placed close to the tail race of the turbine.
8. Turbine that consists of draft tubes is called as__________
a) Impulse turbine
b) Curtis turbine
c) Rateau turbine
d) Reaction turbine
Explanation: A turbine that consists of draft tubes is called as a reaction turbine. Reaction turbines make maximum use of the draft tubes for improving its performance characteristics.
9. Which of the following is a 50 percent reaction turbine?
a) Parsons turbine
b) Curtis turbine
c) Rateau turbine
d) Pelton wheel
Explanation: A turbine that consists of moving nozzles which are alternating with the fixed nozzles is called as a reaction turbine. When the steam hits the nozzle, the pressure is decreased and the temperature is increased. It is also called as Parson’s turbine.
10.The simple elbow draft tube helps to cut down the cost of excavation.
a) True
b) False
Explanation: The simple elbow draft tube helps to cut down the cost of excavation. The simple elbow draft tube is placed close to the tail race. It consists of an extended elbow type tube. It is mainly used in the Kaplan turbine. It is placed close to the tail race of the turbine.