Question

After reading the textbooks and supplemental material on turbine engine theory and construction, you learned about pressure waves and their ability to change the speed and static pressure of the air stream. Define the three types of pressure waves and explain which type of pressure wave you think is commonly found in a turbine engine and why.

Three types- normal shock wave, oblique shock wave, & expansion wave. Not sure which one is for turbine engines. Thanks in advance!

Answer 1

Normal shock wave: In a flow passage, when there is an abrupt pressure rise within and at the exit across a thin discontinuity s called as normal shock wave. Oblique shock wa Similarly, if there is less abrupt pressure rise or drop of pressure while exiting the duct, such a type of wave is called oblique shock wave or expansion waveS ve Two cases can be considered here Overexpanded: The flow is called overexpanded, if the pressure rises down stream of the duct exit Underexpanded: The flow is called underexpanded, if the pressure drops downstream of the duct exit. In a turbine, the pressure drops due to expansion of steam as it passes through the blades. When the compressed flow tries to decelerate upon hitting the turbine blades, shock wave is formed. These affect the blade structural performance and aerodvnamics of the blade. So, generally we find oblique shock waves/ expansion waves in a turbine.

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