Numerical and Experimental Investigations of Steam Condensation in LP Part of a Large Power Turbine

Abstract

This paper presents the experimental investigations of steam flow with condensation in the blading system of the low-pressure (LP) part of a 360 MW turbine. To this end, special probes were used, which provided flow visualization opportunities including localization of the front of condensation, determining distributions of pressure, temperature, velocity, and flow angle in the inter-row gaps, measurements of water droplet concentration and sizes. The measurements have proved that the condensation process in the LP turbine might be of heterogeneous nature, depending on the concentration of chemical impurities in steam. The measurement results constituted the basis for computational fluid dynamics (CFD) flow calculations, which were performed using the time-dependent 3D Reynolds averaged Navier–Stokes equations coupled with two-equation turbulence model (k-ω SST) and additional conservation equations for the liquid phase. The set of governing equations has been closed by a “local” real gas equation of state. The condensation phenomena were modeled on the basis of the classical nucleation theory. The heterogeneous condensation model on the insoluble and soluble impurities was implemented into presented CFD code. The system of governing equations was solved by means of a finite volume method on a multiblock structured grid. The obtained numerical results and experimental data were compared and discussed.

Numerical modelling of steam condensing flow in low and high-pressure nozzles

“…The flow governing equations are formulated for the vapour/liquid mixture (single-fluid model). The validation of the code was made for both the nozzle flow and the steam turbine cascade many times, showing applicability in a practical analysis [4,11,12]. Since the boundary layers for most condensing flows in nozzles working under normal conditions are very thin and have no impact on the flow in the middle section, in our calculations the flow was considered as laminar.…”

Wetness loss prediction for a low pressure steam turbine using computational fluid dynamics

“…6 Investigations using Reynolds-averaged Navier-Stokes solvers were conducted by Heiler,7 who also spent much work in validation of the specific wet steam models. Three-dimensional investigations have been realised by Wroblewski et al 8 and, especially, Gerber et al, 9,10 whose Euler-Euler method is used for the present work. A more detailed overview about theoretical treatments of wet steam flows is given by Bakhtar et al 11 Knowledge about the behaviour of losses is a precondition for any kind of flow efficiency improvement.…”

A Study of Spontaneous Condensation in an LP Test Turbine

“…Comparisons between numerical predictions and measured data for model or full-size turbines have been presented for a limited number of operating conditions [4,[6][7][8]. Of particular relevance to this work is the study performed by Eberle et al [9] that compared experimental and numerical results for different inlet Information contained in this document is indicative only.…”