How Much You Know About Gas Turbine? Trivia Quiz

Hydrodynamic journal bearing is a bearing operating with hydrodynamic lubrication, in which the bearing surface is separated from the journal surface by the lubricant film generated by the journal rotation.

The bleed valve is a crucial component in a compressor system as it helps to protect the compressor from surging. Surging occurs when the airflow through the compressor becomes unstable, leading to a decrease in efficiency and potential damage to the compressor. By opening the bleed valve, excess air is released from the system, preventing surging and ensuring the compressor operates smoothly and efficiently. Therefore, the statement that the bleed valve is used to protect the compressor from surging is true.

The statement "The gas turbine needs no starting device" is false. Gas turbines require a starting device to initiate their operation. This is typically achieved through the use of an electric motor or a small auxiliary gas turbine known as a starter motor. The starting device helps to spin the main turbine rotor until it reaches a sufficient speed for the combustion process to begin. Without a starting device, the gas turbine would not be able to start and operate effectively.

The fire hazard valve is designed to ensure safety by automatically shutting off the gas supply in emergency situations or during regular shutdowns. This helps prevent potential accidents or fires caused by gas leaks or other hazards. Therefore, the statement that the fire hazard valve is a safety device that shuts the gas supply in case of emergency or during normal shutdown is true.

The Brayton cycle is a thermodynamic cycle that describes the workings of the gas turbine engine, basis of the jet engine and others. It is named after George Brayton (1830–1892), the American engineer who developed it,

High shaft speeds and low bearing loads result in hydrodynamic friction because hydrodynamic friction occurs when there is a sufficient fluid film between the surfaces of the shaft and the bearing to create a lubricating effect. This film is created when there is relative motion between the surfaces and a pressure gradient is established, which is more likely to occur at high speeds and low loads. Therefore, the statement is true.

Separators designed for use in the gas industry are mechanical devices, which remove liquids from the natural gas stream.

Boundary friction occurs during starting and coast down of a machine. This is because during these phases, there is a decrease in speed and an increase in load on the machine. Boundary friction is a type of friction that occurs when two surfaces are in direct contact with each other, and it is influenced by factors such as surface roughness and lubrication. In high speed and low load conditions, other types of friction, such as fluid friction, may dominate over boundary friction.

it detects low oil pressure in the bearing header
it will alarm if pressure attained pre set value
it will trip the turbine if again pressure reduced further value

in lead wire there is spring back

The explanation for the given correct answer, which is False, is that the bleed valve is not used for bleeding compressed air for cooling compressor liners. The bleed valve is actually used to release excess air pressure from the compressor system. It helps maintain the optimal pressure levels within the system and prevent any damage or malfunctioning due to excessive pressure. Cooling compressor liners is typically achieved through other means, such as using cooling air or coolant circulation systems.

The gas turbine starting device serves multiple functions. It supplies high torque at zero speed, allowing the turbine to start from a standstill. It also drives the unfired gas turbine to an acceptable firing speed, ensuring that it reaches the necessary speed for combustion. Additionally, it assists the fired turbine to a self-sustaining speed, maintaining the turbine's operation once it has started. Therefore, the correct answer is "all the above" as it encompasses all the mentioned functions of the gas turbine starting device.

Tin base white metal is the most commonly used journal bearing material in gas turbines. This material offers excellent anti-seizure properties, high load-carrying capacity, and good corrosion resistance. It also has low friction characteristics and is able to withstand high temperatures and pressures typically found in gas turbine applications. Additionally, tin base white metal has good conformability, allowing it to adapt to minor misalignments or surface imperfections, ensuring smooth operation and reducing wear.

Journal bearing clearance cannot be measured using a feeler gauge. Journal bearing clearance is the gap between the journal (rotating part) and the bearing (stationary part) in a machine. It is typically measured using specialized tools such as dial indicators or micrometers, which provide more accurate and precise measurements than a feeler gauge. A feeler gauge is commonly used to measure gaps and clearances in other applications, but it is not suitable for measuring journal bearing clearance.

Journal bearings are designed to support only radial loads, not axial loads. The axial load is supported by thrust bearings, which are specifically designed for this purpose. Therefore, the statement that journal bearings support both radial and axial loads is false.

When a rotor undergoes differential contraction, it means that different parts of the rotor contract at different rates. This can cause the rotor to bend or deform. In the case of upward bending, it is referred to as "shaft hog". This term is commonly used in the context of turbines and generators, where the upward bending of the rotor shaft can cause misalignment and other operational issues.