Category: Fluid Mechanics And Hydraulic Machines

Area of flow at inlet = , where D0 is outer diameter of runner and Db is hub diameter. Velocity triangle is similar to velocity triangle of Francis turbine. Only difference is that the velocity of flow at inlet and outlet in Kaplan turbine is same as shown in Figure 9.15. Figure 9.15 Velocity Triangle for Kaplan Turbine Velocity of flow at…

Kaplan turbine is an axial flow, low head, high specific speed, reaction type turbine. There is a similar turbine known as propeller turbine having fixed vane in place of adjustable vane as in Kaplan turbine. Kaplan turbine has the following components (Figures 9.13 and 9.14): Figure 9.13 Main Components of Kaplan Turbine Figure 9.14 Kaplan Turbine Scroll Casing: Its function…

Velocity triangle for Francis turbine is shown in Figure 9.12. Figure 9.12 Velocity Triangle for Francis Turbine Here, The work done per second on runner by water, The work done per second per unit weight of water =  where +ve sign is taken if β < 90; −ve sign is taken if β > 90, and Vω2 = 0, if β = 90. In case…

Figure 9.11 shows the different shapes for draft tubes. Figure 9.11 Different Types of Draft Tubes

Following are the components of Francis turbine (Figure 9.9) Figure 9.9 Francis Turbine Penstock: Penstock is a waterway to carry water from the reservoir to the turbine casing. It is very similar to all types of turbines. Spiral or Scroll Casing: In a spiral casing, the cross-sectional area decreases around the periphery of guide wheel from the entrance…

Initially, Francis turbine was designed as a pure radial flow reaction turbine by an American engineer James B. Francis. Modern Francis turbine is mixed flow reaction turbine as water enters the turbine in radial direction and exits in axial direction. It operates under medium heads and also requires medium quantity of water. It is employed…

Here, In the case of Pelton wheel, α = 0, θ = 0, u1 = u2 = u = πDN/60, V1 = Vω1, Vr1 = V1 − u1 = V1 − u where D is diameter of wheel and N is rpm. where H is net head equals to Hg − Hf. Hg and Hf is gross and friction heads, respectively, Cv is co-efficient of velocity. From Velocity Triangle (in Figure 9.8b) Figure 9.8 (a) Velocity Triangle for Series of Radial Vane, and (b) Velocity Triangle for Pelton Turbine For maximum efficency,       Example 9.6: A Pelton…

Specific speed of the Pelton turbine ranges from 10 to 35. If the speed of the turbine is made higher, following changes may be required: Hydraulic Brake: To stop the turbine quickly in short interval of time, some smaller nozzles are fixed in such a way that water jets strike the bucket from back side.

Pelton turbine is named after L. A. Pelton an American engineer; it is a high head, tangential flow and low specific speed turbine. This turbine is most suitable for high head. In the case of low head, flow is to be increased and for increased flow a bigger jet diameter is required. The bigger jet…

Direction of Flow of Water Head Specific Speed of the Turbine