What is a Crossflow Turbine? | How does a Cross-flow Turbine Work?

Introduction:

In this article, I will explain the crossflow turbine that is a well-known kind of turbine from the category of impulse turbine. I will also explain the cross-flow turbine working principle and components with the help of a diagram. So, Crossflow turbines are special water turbines designed for micro and small hydroelectric power projects with a high flow rate. It is a low-head turbine. Anthony Michelle invented it in the 1903s.

Hydroelectric power is one of the ideal supplies of energy due to its environmental protection. In the current few years, more and more research has been carried out in the field of the small hydropower plant. Different kinds of mini hydroelectric power water turbines include propeller turbines, axial turbines, and radial turbines. There are multiple good places for low-height turbines.

cross flow turbine

The cross-flow water turbine efficiency depends on various parameters or design factors. These factors contain the impeller length, the impeller diameter, the blade bending radius, the turbine power, the impeller speed, the number of buckets, the bucket pitch, the angle of attack, the draft angle, and the bucket angle. A cross-flow turbine is a high-flow and low head turbine. Therefore, it is a special low-speed turbine. Below given diagram shows the cross-flow turbine.

Kaplan turbine is a low head turbine that is an axial outlet and axial inlet. Crossflow turbine is also a low head turbine with radial outlet and inlet. These are the main areas of interest. At present, the cross-flow water turbine is becoming increasingly popular due to its simple design and ease of on-site manufacture in locations with low head and low flow rates.

Crossflow Turbine Working:

The working principle of the cross-flow turbine is very simple.

cross flow turbine working

The Crossflow turbine has a drum-shaped rotor with fixed disks at both ends, and trough-designed buckets connect the two disks. The water is led from the inlet guide to the rotor. The inlet guide guides the water under pressure to the rotor for the first time, transfers the impulse force inside the drum. After this process, the water passes the rotor and leaves the turbine at ambient pressure.

The cross-flow turbine then changes the water pressure and converts it into mechanical energy. This effect reduces the pressure drop in very little amount across the buckets of the turbine and improves efficiency. Most part of the energy extracts from the top buckets (around 75%) and the remaining 25% from the bottom buckets.

The angular momentum of the water flowing through the turbine rotor buckets converts the kinetic energy of the water into torque on the output shaft, with which the generator can be driven in a small hydroelectric system. The cross-flow water turbine then turns the coil of the generator coupled to the electrical load. Depending on the building, the generator supplies electricity to a building or an industrial area.

For a better understanding, watch the below-given video:

Crossflow Turbine Components:

Components of the cross-flow turbine are given below.

cross-flow turbine components

1) Runner:

The runner includes in the most important components of the cross-flow turbine. It makes of two parallel discs in which several curved buckets are used to connect them. The impeller is a hollow circular cross-section of the turbine that supports both ends of the curved buckets.

2) Nozzle:

The nozzle is an integral part of the turbine and can create high-speed water flows. The jet of water hits the impeller buckets and converts potential energy into kinetic energy. The nozzle also includes in the most important components of the cross-flow turbine.

3) Buckets:

The edges of the buckets are sharp to decrease water flow resistance. The cross-sectional area of the bucket metal is circular. The blade’s ends are welded to the disc to make a cage that resembles a hamster cage. This is sometimes referred to as a “squirrel cage turbine“.

4) Housing:

The housing of the cross-flow turbine prevents from the splashing of water in the outside area.

Crossflow Turbine Advantages and Disadvantages:

Advantages:

  1. it has a very low price.
  2. These turbines have good regulation.
  3. It does not require too much maintenance.
  4. Crossflow turbine is more dependable as compared to other types.
  5. The efficiency is high when the water flows through the impeller twice.
  6. These are mainly used in micro and small hydroelectric plants.
  7. The benefit is that it also removes small contaminants and debris from the impeller when the water leaves the impeller.
  8. The annual efficiency generated by the flat efficiency curve is superior to other turbine systems, especially for the mini-run of the water power plants.
  9. The output of belt power can come from both sides of the cross-flow water turbine.

Disadvantages:

  1. Problems for self-starting
  2. It reduces the coefficient of performance.
  3. The maximum efficiency of the cross-flow turbine is slightly lower than the maximum efficiency of Pelton, Francis, and Kaplan turbines.

In this article, I deeply explain to the cross-flow turbine and its working principle. It is the most efficient type of impulse turbine. If you need any more help related to this topic, then feel free and let me know in the comment section.

For more reading about turbines, you should read the below-given articles.

1) Turbine and its types

2) Impulse Turbines

3) Reaction turbines

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