Axial-flow turbines reaction turbine

The degree of reaction in an axial-flow turbine is the ratio of change in the static enthalpy to the change in total enthalpy... 

An example of a typical turboexpander is shown in Fig. 29-46. Radial-flow turbines are normally single-stage and have combination impulse-reaction blades, and the rotor resembles a centrifugal-pump impeller. The gas is jetted tangentially into the outer periphery of the rotor and flows radially inward to the eye, from which the gas is jetted backward by the angle of the rotor blades so that it leaves the rotor without spin and flows axially away. 

The two types of turbines—axial-flow and radial-inflow turbines—can be divided further into impulse or reaction type units. Impulse turbines take their entire enthalpy drop through the nozzles, while the reaction turbine takes a partial drop through both the nozzles and the impeller blades. 

TTiere are two main types of expansion turbines axial flow and radial flow. Axial flow expansion turbines are like conventional steam turbines. They may be single-stage or multistage with impulse or reaction blading, or some combination of the two. Turbines of this type are used as power recovery turbines. They are used where flow rates, inlet temperatures, or total energy drops are very high. 

In certain cases, the primary process objective is to keep solid particles in suspension. Areas of application involve catalytic reactions, crystallization, precipitation, ion exchange, and adsorption. Axial flow and pitched-blade turbines are best suited in providing the essential flow patterns in a tank to keep the solids in suspension. The suspended solid is characterized by two parameters ... 

From an internal design perspective, the steam turbine is either an impulse-or a reaction-type design. In the United States, almost all turbine designs are of the axial flow variety, and only a small number are of the tangential flow variety. In Europe, a significant number of turbines are of the radial flow... 

In Figure 15.6 the flow patterns in a baffled tank, generated by an axial-flow propeller and a radial-flow turbine stirrer, are shown. A large variety of stirrers is available (Figure 15.7). The selection is made initially based on the viscosity of the reaction mixture [54]. 

In the reaction design, approximately equal pressure drop occurs in the nozzles and buckets. To reduce the associated axial thrust on the rotor, a drum construction is used with the reaction design, as shown in Fig. 6.80. Even with a drum rotor, it is usually necessary to build a balance piston into the rotor to balance the stage thrust, unless the turbine section is double-flowed. 

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