Table of Contents
What is specific speed in pump?
The specific speed (ns) is a characteristic coefficient derived from the similarity conditions which allows a comparison of impellers of various pump sizes even when their operating data differ (flow rate and head at best efficiency point, rotational speed).
What is the effect of pump speed on the performance of the pumps?
Pump Performance Pump efficiency also increases with pump rotational speed, especially high speeds. The increase is not as pronounced at 3,600 rpm and below. Specific speed also affects head-capacity curve shape. Low specific speeds (500 to 1,500) produce flat curves.
What is specific speed of reaction turbine?
Explanation: specific turbines of reaction turbines such as francis and kaplan lie under the range 10-100.
How is turbine selection based on specific speed?
Turbine types can be classified by their specific speed, N, which always applies at the point of maximum efficiency. If N ranges from one to 20, corresponding to high heads and low rotational speeds, impulse turbines are appropriate.
Why is specific speed important?
Specific speed is an index used to predict desired pump or turbine performance. i.e. it predicts the general shape of a pump’s impeller. It is this impeller’s “shape” that predicts its flow and head characteristics so that the designer can then select a pump or turbine most appropriate for a particular application.
How does the specific speed of a centrifugal pump differ from that of a turbine?
The effect of the shape of rotor on specific speed is also similar to that for turbines. That is, radial flow (centrifugal) impellers have the lower values of compared to those of axial-flow designs. Similar to turbines, the higher is the specific speed, the more compact is the machine for given requirements.
What is the importance of the specific speed?
Why is it used in a reaction turbine?
Applications. It is most widely used turbine in hydro-power plants, to generate electricity. It is the only turbine to get maximum power output from a low available water head and high velocity other than cross-flow turbine which not that efficient.
Why is turbine selection important?
When the specific speed of the selected turbine is not up to the required range, then the rotational speed of turbine reduces thus the capacity of plant reduces….2. Specific speed.
| Type of Turbine | Specific speed range |
|---|---|
| Kaplan turbine | 300 – 1000 |
| Bulb turbine | 1000 – 1200 |
Which turbine has high specific speed?
Kaplan turbine
Explanation: The specific speed of Kaplan turbine ranges from 600 to 1000 rpm. It is a low head axial flow turbine. From the table, we can conclude that the Kaplan turbine has the highest specific speed.
Which turbine is low specific speed turbine?
Low specific speed of turbine implies it is. propeller turbine.
What do you understand by specific speed of centrifugal pump?
Specific speed is defined as “the speed of an ideal pump geometrically similar to the actual pump, which when running at this speed will raise a unit of volume, in a unit of time through a unit of head”.