FAA Powerplant Written Practice Test

What is referred to as the blade profile of a turbine engine compressor blade?

1. A cutout that reduces blade tip thickness

2. The angle of attack

3. The overall blade height

4. A measure of blade stiffness

The correct answer is: A cutout that reduces blade tip thickness

The blade profile of a turbine engine compressor blade refers specifically to the shape and aerodynamic characteristics of the blade along its length and across its height. This includes features such as the curvature, thickness, and contour that affect the airflow over the blade surface. A cutout that reduces blade tip thickness can significantly influence performance aspects like minimizing drag, improving efficiency, and managing separation of airflow at the blade tip, all of which are critical for optimal compressor operation. In contrast, factors like the angle of attack pertain to the orientation of the blade relative to the incoming airflow, which affects lift but is not the defining characteristic referred to as the blade profile. Similarly, the overall blade height is a physical dimension that does not provide a complete picture of the blade's aerodynamic shape. A measure of blade stiffness focuses on the material properties and structural integrity of the blade rather than its aerodynamic profile. Each of these other aspects contributes to the performance of compressor blades but does not specifically define what constitutes the blade profile.