Which of the following is true regarding surge in a centrifugal compressor?

• A. It occurs at maximum flow conditions
• B. It leads to compressor efficiency improvement
• C. It indicates aerodynamically unstable operation
• D. It is a desirable operating condition

Answer: (C)

In centrifugal compressors, surge is a phenomenon that signifies a loss of aerodynamic stability. During surge, the flow through the compressor reverses, causing fluctuations in pressure and flow rates. This is typically associated with operating conditions where flow becomes too low, leading to the compressor operating outside its designed performance range. The occurrence of surge indicates that the compressor is in an unstable operating regime, which can cause severe mechanical stress and potential damage to the equipment.

Understanding surge is crucial for proper compressor operation, as it can drastically affect the performance and efficiency of the compressor. Therefore, recognizing surge as an indication of aerodynamically unstable operation is vital for maintaining the reliability and longevity of the system.