Question

If the turbine nozzle operates at a higher pressure ratio than the design value, then it is called as

• A. super critical condition
• B. critical condition
• C. subcritical condition
• D. abnormal condition

Hint:

Supercritical flow means operating beyond critical pressure ratios.

Answer 1

The Correct Option is A

In aerospace engineering, the operation of a turbine nozzle is crucial as it impacts the performance of the turbine and the overall engine. The nozzle operates by expanding gases to provide thrust or power extraction.

The concept of pressure ratio is important here. It is defined as the ratio of the pressure at the nozzle entry to the pressure at the nozzle exit. The design condition for a nozzle is typically optimized for a specific pressure ratio, known as the design pressure ratio. Operating beyond this ratio has specific implications:

• Critical condition: This is when the nozzle operates exactly at the design pressure ratio. It is the condition for optimal performance.
• Supercritical condition: This occurs when the nozzle operates at a pressure ratio higher than the design value. This can lead to improved performance under specific circumstances by allowing more expansion of the working fluid.
• Subcritical condition: This is when the pressure ratio is less than the design value, typically resulting in underperformance.
• Abnormal condition: This is not a specific technical term but can refer to any operation outside the expected or safe performance parameters.

In this context, when the turbine nozzle operates at a higher pressure ratio than the design value, it is termed as operating under a supercritical condition.