Steam turbine classifications Steam turbines can be classified on multiple bases. Which grouping below correctly lists common classification criteria?

Introduction / Context:
Correctly classifying turbines helps in selecting the right machine for a duty and in understanding performance maps. Steam turbines are grouped by how steam moves, how many stages share the total enthalpy drop, and whether expansion occurs only in stators (impulse) or in both stators and rotors (reaction).

Given Data / Assumptions:

• Industrial and utility steam-turbine practice.
• Standard terminology in turbomachinery.
• Single- or multi-cylinder configurations may exist under each category.

Concept / Approach:
Common classification axes include: (1) direction of flow (axial, radial-inflow, mixed), (2) number of stages (affecting speed and efficiency), and (3) mode of action (impulse versus reaction). Many real machines are axial multi-stage with mixed impulse–reaction blading, but the categories remain foundational for study and specification.

Step-by-Step Solution:
Review flow direction: axial is most common; radial-inflow is used in small stages; mixed combines components.Review staging: single-stage for small drops and controls; multi-stage for large pressure ratios and high efficiency.Review mode of action: impulse stages expand in nozzles only; reaction stages expand in both rows.Hence, all listed criteria are valid classification bases.

Verification / Alternative check:
Manufacturers’ catalogs and standards specify turbines by these axes (e.g., axial multi-stage reaction machine for condensing service).

Why Other Options Are Wrong:
Picking a single axis omits other equally standard bases used in engineering documentation.

Common Pitfalls:
Assuming “impulse” or “reaction” refers to flow direction; they are independent concepts.

Final Answer:
All of these