SP 2: GT Materials & Damage Mechanisms

What is the highest thermal efficiency of the latest Simple Cycle & Combined Cycle GT power plant?

• ~25% & ~30%

• ~30% & ~40%

• ~35% & ~50%

• ~44% & ~64%

Name the component of the rotating section in a gas turbine which experienced highest temperature.

• Combustor

• Turbine

• Compressors

• Exhaust

Based on the thermal cycle, name two (2) parameters that will determine the thermal efficiency of a gas turbine.

• Turbine inlet temperature & exhaust temperature

• Compressor pressure ratio & turbine inlet temperature

• Combustor temperature & compressor inlet temperature

• Compressor pressure ratio & compressor inlet temperature

In a gas turbine which components experience the highest temperature and stress?

• Stage 1 turbine rotating blade

• Stage 1 compressor blade

• Stage 5 compressor blade

• Stage 1 turbine stationary vane

Select types of inspection interval calculations (formula) used by certain OEMs to determine the maintenance cycles.

• Equivalent Operating Hours (EOH)

• Factored Fired Hours (FFH) and Factored Starts (FS)

• Equivalent Based Hours (EBH) and Equivalent Starts (ES)

• All above

Select the correct sequence of inspections and approximate durations to perform the work scopes on a GE Frame 6B gas turbine.

• Hot Gas Path Inspection (7 days), Combustion Inspection (14 days) and Major Inspection (30 days)

• Combustion Inspection (7days), Hot Gas Path Inspection (14 days) and Major Inspection (30 days)

• Combustion Inspection (14 days), Hot Gas Path Inspection (7 days) and Major Inspection (30 days)

• Major Inspection (14 days), Combustion Inspection (7 days) and Hot Gas Path Inspection (30 days)

Below are among the important properties of a superalloy used in gas turbine.

• High temperature strength and low oxidation resistance

• High temperature strength and high oxidation resistance

• High fatigue cracking resistance

• a & c

• b & c

Among the fabrication methods used for fabrication of gas turbine blades below, which is the best material to use for Stage 1 turbine rotating blades for a latest model GT?

• Conventional Cast

• Directional Solidified

• Single Crystal

• Wrought Alloys

Coarsening of gamma-prime (ɣ') in superalloys will cause degradation of the materials and this will increase the creep strength and tensile strength.

• True

• False

TBCs typically consist of a Yttria Stabilized Zirconia (YSZ) ceramic coating layer that is applied over a metallic MCrAlY bond coat. The primary function of YSZ is oxidation resistant and MCrAlY is to reduce the transfer of heat into the underlying base material.

• True

• False