When vanes are fixed to hub and they are not adjustable then the turbine is?

Explanation:

• In a propeller turbine, the vanes or blades are indeed fixed to the hub and they are not adjustable. This makes them distinct from Kaplan turbines, which also have propeller-like blades, but these blades can be adjusted to maximize efficiency at different flow rates or heads.
• A propeller turbine has a relatively simple design, consisting of a propeller attached to a rotating shaft. When fluid (like air or water) flows over these fixed blades, it causes the rotor to spin, which turns the turbine and generates energy.
• The angle of attack, or the angle at which fluid meets the blades, is fixed, making the turbine more efficient under consistent flow conditions.
• Because the angle of the blades in a propeller turbine cannot be adjusted in response to changes in flow or load, the efficiency of a propeller turbine can decrease under varying operating conditions.
• However, despite this potential loss of efficiency, propeller turbines see substantial use due to their simplified design, lower manufacturing cost, and ease of maintenance compared to variable-pitch turbines.