Question

Which force(s) provide(s) the flow necessary for the mixing action?

• A. Radial only
• B. Radial and longitudinal
• C. Tangential
• D. Rotational

Hint:

To prevent pure tangential swirling (vortexing) and convert it into highly useful radial and longitudinal mixing currents, vertical metal strips called baffles are installed along the walls of the mixing tank.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Agitation and mixing of fluids in processing vessels are achieved by rotating impellers.
The impeller imparts mechanical energy, generating fluid flow in three dimensional directions: radial, axial (longitudinal), and tangential (rotational).

Step 2: Detailed Explanation:
- Tangential flow: Flows parallel to the path of the impeller circle. It causes circular swirling and vortex formation, which does not contribute to efficient mixing.
- Radial flow (perpendicular to the shaft) and Longitudinal/Axial flow (parallel to the shaft): These two flow components generate the bulk turnover, top-to-bottom circulation, and shearing forces necessary to achieve homogeneous mixing of materials.
Therefore, the combined action of radial and longitudinal flows is essential for effective mixing.

Step 3: Final Answer:
The necessary flow for mixing is provided by radial and longitudinal forces, corresponding to option (B).