Identify the pump type: which class of pumps is designed for primarily axial flow through the impeller passage?

Introduction / Context:
Pumps are categorized by predominant flow direction: radial, mixed, or axial. Recognizing axial-flow pumps is essential for low head–high flow applications such as circulation, flood control, and condenser water systems.

Given Data / Assumptions:

• Axial-flow geometry implies flow essentially parallel to the pump shaft.
• Applications demand high volumetric throughput at relatively low heads.
• Terminology aligns with common industry usage (propeller, axial-flow, tubular pumps).

Concept / Approach:

Propeller pumps are classic axial-flow pumps. The impeller resembles a boat propeller; energy addition primarily increases the liquid’s axial momentum. By contrast, turbine (radial) pumps develop head via centrifugal action, and diffuser is a stationary component used to recover pressure, not a standalone pump type.

Step-by-Step Solution:

Verification / Alternative check:

Manufacturer catalogs and pump handbooks list “propeller pumps” under axial-flow family, often supplied as vertical mixed/axial variants for cooling water and irrigation services.

Why Other Options Are Wrong:

Turbine pump: Primarily radial flow. Diffuser pump: Diffuser is a pressure-recovery component; not the axial-flow category name. None of these: Incorrect because propeller pump is the standard axial-flow type.

Common Pitfalls:

Confusing mixed-flow with axial-flow; assuming “turbine” implies axial (it does not in pump context).

Final Answer:

Propeller pump