Open cooling of turbine blade rows—detailed fluid mechanics and thermodynamics

Open cooling of turbine blade rows—detailed fluid mechanics and thermodynamics 

The preliminary a/s analyses of turbine cooling described above contained two assumptions  

In Chapter 5 (and Appendix A), the detailed fluid mechanics and thermodynamics involved in cooling an individual turbine blade row are discussed, enabling if/ to be 

We concentrate here on open loop cooling in which compressor air mixes with the mainstream after cooling the blade row, the system most widely used in gas turbine plants (but note that a brief reference to closed loop. steam cooling in combined cycles is made later, in Chapter 7). For a gas turbine blade row, such as the stationary entry nozzle guide vane row where most of the cooling is required, the approach first described here (called the simple approach) involves the following  

From (a) and (b), the stagnation pressure and temperature can thus be calculated at exit from the cooled row they can then be used to study the flow through the next (rotor) row. From there on a similar procedure may be followed (for a rotating row the relative (7 o)r, i and (po)k replace the absolute stagnation properties). In this way, the work output from the complete cooled turbine can be obtained for use within the cycle calculation, given the cooling quantities ip. 

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