This set of Mechanical Operations written test Questions & Answers focuses on “Flow Patterns”.
1. How can pitch be defined with respect to flow patterns during mixing?
a) Distance covered by liquid due to any chosen component
b) Distance covered by liquid during axial flow
c) Distance covered by liquid during tangential flow
d) Distance covered by liquid during radial flow
Explanation: Axial flow is the flow that takes place along the axis of rotation and is also known as longitudinal flow. Radial flow is towards the center and can also be called centripetal flow. Tangential or the circular component, is the flow along the tangent at point.
2. The given diagram represents which type of flow?
a) Radial flow
b) Rotational flow
c) Axial flow
d) Tangential flow
Explanation: The arrows depict a top to bottom motion of the fluid which indicates axial flow. Axial flow is employed when thorough top to bottom mixing in tanks is necessary. Axial impellers are suitable when stratification or solid suspension is needed.
3. Which of the following is not an example of axial flow impellers?
b) Low level mixing impeller
c) Pitched blade
Explanation: Propellers are axial flow impellers that are used in small and portable mixers. Pitched blades are also axial flow impellers that are used when a balance between flow and shear is required. Hydrofoil is an axial flow impeller used when low turbulence is required.
4. Which of the following statements is true about radial flow impellers?
a) They are typically available with 4 or 6 blades
b) They provide lower shear when compared to axial flow impellers
c) They provide greater flow per unit of horsepower supplied, when compared to axial flow impellers
d) They are not sensitive to viscosity
Explanation: Radial flow impellers provide higher shear force and lower flow per unit when compared to axial flow impellers. For the same power supplied, radial impellers have a lower tank turnover flow when compared to axial impellers. They are also sensitive to viscosity.
Sanfoundry Global Education & Learning Series – Mechanical Operations.
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