24 Questions
In terms of flow pattern analysis, which component is perpendicular to the impeller shaft?
Radial
Which term describes a flow component parallel to the impeller shaft?
Axial
Which component of flow pattern analysis is typically parallel to the circle of rotation around the impeller shaft?
Axial
What type of flow component is tangential to the circle of rotation around the impeller shaft?
Tangential
What flow pattern component is perpendicular to both the axial and tangential components?
Radial
What type of flow is desired when using turbines with blades set at a 90-degree angle to their shaft?
Radial-tangential flow
In what direction are the blades set in turbines that are designed for radial-tangential flow?
At a 90-degree angle to the shaft
What is the main characteristic of turbines designed for radial-tangential flow?
Blades set at 90-degree angle to their shaft
Which flow type is least likely to be achieved with turbines having blades set at a 90-degree angle to their shaft?
Vertical flow
How are the blades oriented in turbines to achieve radial-tangential flow?
At an oblique angle to the shaft
What is the primary direction of circulation in this type of mixer?
Tangential
Which concentration gradients may persist even after prolonged operation?
Both axial and radial concentration gradients
What happens to the concentration gradients in the tangential direction over time?
They may persist
Which statement best describes the persistence of concentration gradients in this type of mixer?
The gradients may persist even after prolonged operation
How do jets differ from propellers?
Jets themselves do not generate tangential flow like propellers.
What is a common method of operating jets, as described in the text?
Pumping liquid through the jet back into the tank
Why is the process of continuous mixing often desirable?
It ensures freshly mixed material without interruptions
What is a key advantage of continuous mixing over batch mixing?
Uninterrupted supply of freshly mixed material
In the context of mixers, what role do jets play?
Operating by pumping liquid through them back into the tank
What type of flow do these impellers tend to induce?
Tangential flow
Where does the tangential flow induced by these impellers primarily occur?
Near the tank walls
What effect does the tangential flow induced by the impellers have on mixing?
Reduces mixing capabilities
Under what conditions might some mixing occur due to tangential flow?
Near the tank walls where shear forces exist
What is primarily formed due to swirl and vortex formation caused by these impellers?
Vortexes
Study Notes
Circulation in Mixers
- Circulation in mixers is primarily tangential, leading to persistent concentration gradients in axial and radial directions even after prolonged operation.
Flow Pattern Analysis
- The flow pattern in mixers can be broken down into three components:
- Radial (perpendicular to the impeller shaft)
- Axial or longitudinal (parallel to the impeller shaft)
- Tangential (tangential to the circle of rotation around the impeller shaft)
Jet Operation
- Jets can be operated by pumping liquid from the tank through the jet back into the tank.
Continuous Mixers
- Continuous mixing produces an uninterrupted supply of freshly mixed material, making it desirable for handling large volumes of materials.
Impeller Characteristics
- Impellers tend to induce tangential flow, which does not produce mixing, except possibly near tank walls where shear forces exist.
- Turbines with blades set at a 90-degree angle to their shaft are used to achieve radial-tangential flow.
Learn about the three components used to analyze flow patterns: radial, axial or longitudinal, and tangential. Understand how each component relates to the impeller shaft orientation and circle of rotation.
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