NUMERICAL CALCULATION OF CONJUGATE HEAT TRANSFER IN END SEALS OF STEAM TURBINES

The results of the operation of some steam turbines showed that the cracks in the zone of end seals of the high-pressure cylinder arise after long-term operation. The defects could be caused by the cyclic changes of thermal stresses in rotor material, so it is very important to have detailed information about heat transfer conditions in those elements for the following numerical thermal stress calculations. The purpose of this work is the development of effective numerical methodology of definition of the heat exchange conditions in the end seals with thermal compensating grooves by modeling of thermal processes on the basis of solving conjugate heat transfer problems. The heat transfer coefficients on surfaces of the ledges, cavities, and thermal compensating grooves in the zone of the end seal were calculated based on the results of the conjugate heat transfer problem solving. The range of usage of the empirical dependence for the calculation of the heat transfer coefficients on surfaces of the end stepping seals was expanded. The influence of the frequency of rotor rotation on the value of the heat transfer coefficients on its surface was detected. The distribution of the heat transfer coefficients on the rotor surfaces in the zone of end seal during turbine startup was detected. The obtained results could be used for estimation of the service life of a steam turbine.