No abstract

Realization of numerous tests on the droplet size measurement with extinction probe, in a 200 MW low-pressure steam turbine, provides necessary experimental data for testing the theoretical models of the droplet nucleation process in steam turbines. The earlier computational model accounting for the unsteady and viscous effects given by Bakhtar and Heaton and by Guha and Young, where the steam particles follow randomly chosen different streamlines within the blade rows with prescribed polytropic efficiency distribution in the pitchwise direction, thus undergoing various nucleation conditions, has been extended in this paper to consider to some extent two-dimensional effects. Because several uncertainties still exist in the inversion methods, predicting the size distribution of droplets, this contribution is aimed at direct comparison of the computed and measured transmittance data I/I 0 .

The results of geomagnetic soundings in the West Carpathians are presented. The number of observation sites in this region was approximately 90. The data treatment included the calculation of single-station transfer functions and the separation of the fields into external and internal parts on some profiles. The interpretation was based on the construction of twodimensional models explaining the observed features. The observed distribution of geomagnetic induction vectors is very regular and the axis of the anomaly runs in the contact region between the outer and inner Carpathians.The thickness of the well-conducting rock complex exceeds 10 km. The wellconducting rocks seem to be the sediments which accumulated in the contact region of the platform. The asymmetry in the distribution of induction vector amplitudes on some profiles can be accounted for by asymmetrical geometry, which is characteristic of the underthrusting of rocks.

This paper presents the results of a computational analysis of the wet steam energy loss occurring in a 210 MW fossilfired and a 1000 MW nuclear LP steam turbine. The turbines operate under considerably different conditions as regards pressure level in the droplet nucleation zone, exit moisture level and droplet size spectra determined from optical extinction measurements. An evaluation of the basic wetness energy losses has been carried out including the thermodynamic loss, drag loss of the fine and coarse droplets, impact loss, collected water loss, centrifuging loss and exit loss. A statistical 2D evaluation method has been employed for the computational simulation of the loss. The objective of the analysis was to determine whether an equilibrium based Baumann factor of order 0.6 can be used for predicting the wet steam loss.

Linear wave equations for equilibrium and subcooled wet steam are introduced in the paper, accounting for thermal and inertial relaxation processes between the vapour and droplets. Relations for sonic velocity and absorption were found to be frequency dependent. Analysis of propagation of a step pressure disturbance suggests that the frozen speed of sound should be used to define, for example, the direction of characteristics and conditions for choking of a wet steam flow. It is concluded further that in a near-equilibrium approximation the non-linear wave phenomena in a wet steam can be analysed by the Korteweg-deVries-Burger equation, accounting for non-linear, dispersive and dissipative effects.