 Deshmukh, working as an assistant professor in Department of Mechanical Engineering, Vulture Institute of Technology, Solapur. In this video, we are going to learn the classification of water turbine and efficiencies of turbine. The learning outcome, at the end of this session, the learner will be able to classify different types of turbines and their efficiencies. The content, first we will see the introduction to turbines and pumps, then the simple layout of hydroelectric power plant, then the classification of water turbines, and last the efficiencies of turbine. Now, before introduction to turbine, I want you guys to take a break and think on the difference between the turbines and pumps. So, which points makes the turbines and pumps different? Their use, their energy conversion, just note down the different points that you get in our mind. So, before answering these questions, I want you guys to tell, we can convert the energy by using the fluid dynamic machines. So, we can convert either the hydraulic energy to the mechanical energy or the mechanical energy to the hydraulic energy. Based on this energy conversion, we classify the turbines and pumps. So, the turbines, the turbines are the machines which converts the hydraulic energy to mechanical energy. The typical examples of turbines are Peltonville turbine, Francis turbine, and Kaplan turbine. And the pumps, the pumps are the machines which converts the mechanical energy to hydraulic energy. So, the examples of the pumps are centrifugal pumps and reciprocating pumps. Now, the turbines. The word turbine is actually derived from a Latin word turbo, which means vertex. These three machines extract energy from the fluid and convert it into the useful work. With the help of turbine, we can generate the electric power when combined with generators. This is the typical layout of hydroelectric power plant. We construct a dam across a river bed to increase the potential energy of water by increasing its headrest. So, this water with high potential energy is transferred through the penstock and applied to the veins of turbines with the help of nozzle. So, as the stream strikes to the veins of turbine, the turbine rotates which is mounted on the shaft through which we convert the mechanical energy to the electrical energy. And this electricity can be transferred with the help of cables or wires. Now, we will see the classification of water turbines. The water turbines can be classified into following four categories. The first one is according to the type of energy at inlet. The second one is according to the direction of flow of water through turbines. The third one is according to head at the inlet. And fourth one is with the specific speed. So, according to the type of energy at the inlet, the turbines are classified into two subparts. That is, first one is impulse turbine in which we apply the only kinetic energy at the inlet of turbine. And the second one is reaction turbine in which the kinetic energy as well as pressure energy is applied at the inlet of turbine. Now, according to the direction of flow of water through turbine, we classify turbine into four subtypes. Tangential flow turbine, radial flow turbine, axial flow turbine and mixed flow turbine. So, the tangential flow turbine, in the tangential flow turbine, the water flows along the tangent of runner. The example of tangential flow turbine is Peltonville turbine. In figure one, you can see with the help of nozzle, we apply the water jet to the runner. And the direction of the water is along the tangent to the runner. While in radial flow turbine, the water flows in radial direction of runner. In figure two, you can see the water is applied at the runner of the turbine in the radial direction. And with the help of that, we generate electricity. The third type is axial flow turbine in which water flows in axial direction of the rotation of runner. The example of axial flow turbine is Kaplan turbine. The fourth one is mixed flow turbine in which water flows in radial direction but leaves in direction parallel to the axis of rotation of turbine. The example of mixed flow turbine is modern Francis turbine. Now, I want you guys to think on the difference between the axial flow turbine and radial flow turbine. The head of low head turbine is less than 60 meter. While for medium head turbine, the head changes from 60 to 250 meter. And for high head turbine, the head of the turbine is above 250 meter. Then the turbines are also classified according to the specific speed of turbines as low specific speed turbine which rotates at less than 60 rpm. The medium specific speed turbine which rotates at the speed between 60 to 400 rpm and high specific speed turbine which rotates at the speed greater than 400 rpm. Now, we will see the efficiencies of turbine. The efficiency is nothing but the ratio of output to the input. The output is obviously the work done and the input. So, the first we will see the hydraulic efficiency of the turbine. It is defined as the ratio of power delivered to the runner to the power supplied at the inlet. So, power delivered at the runner is known as the runner power and power supplied at the inlet. We are supplying power by the water jet. So, it is called as water power. So, hydraulic efficiency is nothing but the ratio of runner power to the water power. Then the second efficiency is mechanical efficiency. It is defined as the power at the shaft of the turbine to the power delivered by the water to the runner. So, the power at the shaft turbine is known as shaft power and the power delivered by the water to the runner is known as the runner power. So, the mechanical efficiency is nothing but the ratio of shaft power to the runner power. Now, the third one is volumetric efficiency. The volumetric efficiency of the turbine is defined as the volume of water actually striking to the runner to the volume of water supplied to the turbine. Now, we will see the overall efficiency of the turbine. The overall efficiency of the turbine is defined as the power available at the shaft of turbine to the power supplied at the inlet of the turbine. So, power available at the shaft turbine is known as shaft power and the power supplied at inlet is known as water power. So, it is the ratio of shaft power to the water power. Now, we can divide and multiply this formula by the runner power. So, the shaft power upon runner power multiplied by runner power to the water power. Now, we know that the shaft power to the runner power, this ratio is known as mechanical efficiency and the ratio of runner power to the water power is known as hydraulic efficiency. So, the overall efficiency can also be defined as the multiplication of mechanical efficiency to hydraulic efficiency. These are the references.