Which condition commonly leads to compressor stall in a turbine engine?

Which condition commonly leads to compressor stall in a turbine engine?

• A. A lower angle of attack airflow through the first stages of compression
• B. Rapid engine deceleration
• C. A high angle of attack airflow through the first stages of compression
• D. Normal steady-state operation

Answer: (C)

The main idea is that compressor stall happens when the air entering the compressor cannot stay attached to the blade profile because the flow angle is excessive. When the inflow angle is too high, the air can’t follow the contour of the first-stage blades, causing flow separation on the blade surfaces. This disrupts the orderly, high-pressure-rise flow through the early stages and can trigger a cascade of instabilities that lead to stall or surge. A high angle of attack airflow through the first stages pushes the flow past the blades’ designed incidence. The result is a breakdown of the pressure gradient that keeps the flow attached, producing local reversals and turbulent pockets that propagate backward through the compressor. Because the first stages set the stage for the rest of the compressor, disturbance here readily leads to overall instability, making high inlet incidence a common trigger for stall. Lowering the inlet incidence reduces the likelihood of separation, so it’s less prone to stall. Normal steady-state operation implies a balanced, attached flow and does not induce stall. While rapid deceleration can contribute to stall in certain transient conditions, the direct, typical cause among the options is excessive flow angle at the compressor inlet.

The main idea is that compressor stall happens when the air entering the compressor cannot stay attached to the blade profile because the flow angle is excessive. When the inflow angle is too high, the air can’t follow the contour of the first-stage blades, causing flow separation on the blade surfaces. This disrupts the orderly, high-pressure-rise flow through the early stages and can trigger a cascade of instabilities that lead to stall or surge.

A high angle of attack airflow through the first stages pushes the flow past the blades’ designed incidence. The result is a breakdown of the pressure gradient that keeps the flow attached, producing local reversals and turbulent pockets that propagate backward through the compressor. Because the first stages set the stage for the rest of the compressor, disturbance here readily leads to overall instability, making high inlet incidence a common trigger for stall.

Lowering the inlet incidence reduces the likelihood of separation, so it’s less prone to stall. Normal steady-state operation implies a balanced, attached flow and does not induce stall. While rapid deceleration can contribute to stall in certain transient conditions, the direct, typical cause among the options is excessive flow angle at the compressor inlet.