Question

Pressure inside the casing of an impulse turbine is

• A. Negative pressure
• B. Positive pressure
• C. Atmospheric pressure
• D. Atmospheric pressure

Hint:

Turbines: \[ \boxed{ \begin{aligned} \text{Impulse Turbine} &\rightarrow \text{Atmospheric pressure at runner}\\ \text{Reaction Turbine} &\rightarrow \text{Pressure changes across runner} \end{aligned} } \]

Answer 1

The Correct Option is C

Step 1: Recall the working principle of an impulse turbine. In an impulse turbine (such as a Pelton wheel), the entire pressure head is converted into kinetic energy in the nozzle before striking the runner.

Step 2: Determine the casing pressure. The runner operates in air, and the casing is maintained at atmospheric pressure. Therefore, \[ \boxed{\text{Atmospheric Pressure}} \] is the correct answer. Hence, \[ \boxed{(C)} \] is the correct answer.