Category: Steam Engine, Steam And Gas Turbines

The velocity diagram for 50% reaction turbine is shown in Figure 5.15. Since, Also, β1 ≠ β2, the blades are unsymmetrical and ΔVa = 0. There is no axial thrust in 50% reaction turbine. However, there will be considerable tangential thrust produced due to the pressure difference across the blades in each rotor disc since there is pressure…

It is ratio of cumulative heat drops and isentropic heat drops in multistage turbine. The line which joins the actual points at the end of expansion in each stage is known as condition line (Figure 5.14). Figure 5.14 Enthalpy Drops in Multistage Turbine

If steam expands both in nozzle as well as in blades of turbine, i.e., pressure at inlet of the turbine is more than that of outlet, it is known as impulse-reaction turbine. In this case, expansion of steam in nozzle creates impulse on blades and reaction due to minor expansion of steam during passing through…

It is combination of pressure compounding and velocity compounding as shown in Figure 5.9a. There are two rotors and only two rows of moving blades are attached on each rotor because two row wheels are more efficient than three row wheels. The steam on passing through each row of moving blades reduces its velocity, but pressure remains…

In this compounding, whole pressure drop takes place in nozzle (only one row) and remains constant in fixed and moving blades. Velocity of steam remains constant in fixed blades and decreases in moving blades. Figure 5.12a shows a two rows Curtis or velocity staging having two rows of moving blades and one row of fixed blade…

Pressure compounding is splitting of whole pressure drop of steam from steam chest pressure to condenser pressure into series of small pressure drops across several stages of impulse turbine. The whole pressure drops occur in series of nozzles and there is no pressure drop in fixed blades as shown in Figure 5.11. The kinetic energy of steam…

Single row of nozzle with single row of blade is called one stage of turbine. If steam at very high pressure is allowed to expand in single stage of turbine, the blade velocity will be too high. Such a high rotational speed cannot be used properly and also there will be velocity loss at the…

In the impulse turbine, all the pressure drops occur in nozzle and there is no pressure drop of steam passing through blades. Let us consider steam enters the nozzle with pressure of P0 and velocity of V0, after expansion of steam in nozzle pressure drops to P1 and velocity increases to V1. High velocity jet of steam impinges on the blades…

If torque produced on the shaft of the turbine is only due to change in momentum of steam and pressure of steam at inlet and outlet of the turbine being same, it is known as impulse turbine. In this turbine, the expansion of high-pressure steam occurs only in nozzle as shown in Figure 5.8a, b. During…

Broadly, steam turbine can be classified into two categories as follows: Pure reaction turbine cannot be used for practical purpose; therefore, impulse-reaction turbine is referred as reaction turbine.