🔍 Key Concepts

• Dummy piston function in a reaction turbine (what problem is it solving?) • How axial thrust is produced in a reaction turbine and what affects its magnitude • Which factors are design parameters for thrust balancing versus secondary/less critical factors

💭 Think About

• Ask yourself: What is the main purpose of a dummy piston in a reaction turbine, and which variable must it primarily balance? • Which of the listed choices directly affects the amount of thrust acting along the shaft rather than temperature, speed, or volumes? • Think about which factors would be most important to the designer when choosing the piston’s diameter, not just any part of the system.

✅ Before You Answer

• Identify which choice mentions thrust or something that clearly controls axial force on the rotor • Eliminate any options that deal mainly with temperature, RPM, or volumes/pressures that are only indirectly related to thrust balancing • Confirm that the factor you pick would logically be used to size (set the diameter of) a balancing or dummy piston.