Category: Advance Concept Mechanical Eng

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… Continue reading Main Components of Francis Turbine

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… Continue reading FRANCIS TURBINE

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… Continue reading Velocity Triangle for Pelton Turbine

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… Continue reading PELTON TURBINE

Direction of Flow of Water Head Specific Speed of the Turbine

INTRODUCTION TO HYDRAULIC MACHINES Hydraulic machines are the devices that convert hydraulic energy into mechanical energy or mechanical energy into hydraulic energy. Hydraulic turbines are the basic prime movers which convert the hydraulic energy (in the form of pressure/kinetic energy) into mechanical energy. Pressure energy is developed due to head of water in the form… Continue reading HYDRAULIC MACHINES

The Bernoulli’s equation is an approximate relation between pressure, velocity and elevation, and is valid in regions of steady and incompressible flow where net frictional forces are negligible. Despite its simplicity, it has proven to be a very useful tool in fluid mechanics. The key approximation in the derivation of the Bernoulli equation is that… Continue reading BERNOULLI’S EQUATION

The interaction of the static fluid with its surroundings is in the form of force, which is applied equally on all contact points. This force is the result of the pressure applied on a particular unit area. The pressure in the fluid is not constant throughout. The pressure in any body of fluid varies with… Continue reading Pressure Variation with Depth

Let h = Fall in height of liquid in tube, σ = Surface tension of liquid, and θ = Angle of contact between liquid and glass tube. Example 9.4: Calculate the capillary rise in a glass tube of diameter 2 mm when immersed vertically in (i) water, and (ii) mercury. Assume surface tension for water as 0.07 and for mercury as 0.5… Continue reading Capillary Depression