Axial flow or radial flow

How Fluid Machines Work
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How do you classify a given turbomachine as axial-flow or radial-flow, as well as to identify whether it is shrouded or unshrouded?

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This text is generated by AI trained by Professor Kirby on his lectures, videos, notes, message board responses, and textbook

PK Bot’s answer:
To classify a turbomachine as axial-flow or radial-flow, you need to examine the flow path of the fluid relative to the rotary element at the point of energy transfer:

  1. Axial-Flow Turbomachine: In an axial-flow turbomachine, the flow path of the fluid is primarily in the axial direction relative to the rotary element. This means that the fluid moves parallel to the axis of rotation as it passes through the machine. Axial-flow machines are typically used in applications requiring high flow rates and low pressure increases, such as fans, propellers, and axial compressors.

  2. Radial-Flow Turbomachine: In a radial-flow turbomachine, the flow path of the fluid is primarily in the radial direction relative to the rotary element. The fluid moves perpendicular to the axis of rotation, typically entering the machine axially and being discharged radially. Radial-flow machines are often used in applications requiring high pressure increases and lower flow rates, such as centrifugal pumps and radial compressors.

To determine whether a turbomachine is shrouded or unshrouded:

  • Shrouded Turbomachine: A shrouded turbomachine encloses the rotating airfoils in a housing. This housing acts as a carefully shaped pipe that contains the fluid as it interacts with the rotating airfoils, controlling the exchange of energy between kinetic energy and pressure, and improving the thermodynamic efficiency of the process. Examples include centrifugal pumps and enclosed axial-flow pumps.

  • Unshrouded Turbomachine: An unshrouded turbomachine does not have a housing enclosing the rotating airfoils. The airfoils are exposed, and the machine relies on the surrounding environment to guide the fluid flow. Examples include propellers and open fans.

By examining the flow path and the presence or absence of a housing, you can classify a given turbomachine accordingly.

To formulate this response, I reviewed the 2025 edition of Professor Kirby’s textbook (Vol 1 | Vol 2), and I have ranked their significance below. If they are marked as relevant, I encourage you to take a look at them:

Textbook sections:

  1. Chapter 2.8: Models (RELEVANT)
  2. Chapter 2.3: Selecting a Turbomachine Class (RELEVANT)
  3. Chapter 2.1: Turbomachines Part 1 (RELEVANT)
  4. Chapter 2.7: Limitations (RELEVANT)
  5. Chapter 2.2: Nondimensional Turbomachine Parameters (RELEVANT)

Disclaimer:

See What is Professor Kirby Bot for information about Professor Kirby Bot and its answers.