Experimental and Numerical Investigation of the Flow in a LP Industrial Steam Turbine With Part-Span Connectors

Abstract

An experimental and numerical study on the flow in a three stage low pressure (LP) industrial steam turbine is presented and analyzed. The investigated LP section features conical friction bolts in the last and a lacing wire in the penultimate rotor blade row. These part-span connectors (PSC) allow safe turbine operation over an extremely wide range and even in blade resonance condition. However, additional losses are generated which affect the performance of the turbine. In order to capture their impact on the flow field, extensive measurements with pneumatic multi-hole probes in an industrial steam turbine test rig have been carried out. State-of-the-art three-dimensional CFD applying a non-equilibrium steam (NES) model is used to examine the aero-thermodynamic effects of the PSC on the wet steam flow. A detailed comparison between measurement data and CFD results is performed for several operating conditions. The investigation shows that the applied CFD model is able to capture the three-dimensional flow field in LP steam turbine blading with PSC and the total pressure reduction due to the PSC with a generally good agreement to measured values and is therefore sufficient for engineering practice.

Experimental research on the flow at the last stage of a 1090 MW steam turbine

“…However, ventilation regimes have not occurred yet, and angles of the flow still indicate the flow in the direction out from blades along the entire blade length (see Figure 12). In all cases, approximately 0.55 along the length the flow oscillation caused by the tie-boss is noted, which is also proved in Ha¨fele et al 7 For 1090 MW there are stated error bars with the confidence interval 95.5%. The maximum value of estimation of relative uncertainty is AE 1.2% of the measured value.…”

“…Measurements of the effects of steam wetness on the efficiency of the flow passage or individual stages are continuously carried out for example in Starzmann et al 5 and Bosdas et al 6 Much of the work focuses on the effects of continuous binding of blades, 7 on the suction of water films from the surface of blades, 8 and possibly on the development of a measurement system for determining the distribution of fine or coarse water droplets and wetness. [9][10][11] In the 1980s and 1990s, several results from measurements on the parts 12-14 were published.…”

Numerical and experimental study on aerodynamic optimization of part-span connectors in the last stage of a low-pressure industrial steam turbine

“…It has to be noted that this is not a model turbine but instead a full-scale build of the last three stages of a multi-stage industrial steam turbine. A description of the main characteristics of the facility, which is operated with live steam supplied by the combined heat and power plant of the University of Stuttgart, as well as details of the measurement equipment are given in the works of Ha¨fele et al 1,7 Figure 2. Industrial steam turbine test rig at ITSM.…”

“…It has to be noted that this is not a model turbine but instead a full-scale build of the last three stages of a multi-stage industrial steam turbine. A description of the main characteristics of the facility, which is operated with live steam supplied by the combined heat and power plant of the University of Stuttgart, as well as details of the measurement equipment are given in the works of Ha¨fele et al 1,7 In Figure 2, the probe traversing planes and wall pressure measurement locations used for this investigation are indicated. Planes E30 and E32 are equipped with probe traversing systems upstream of stator S3 (E30) and downstream of rotor R3 (E32), allowing the thermodynamic states at any radial location to be evaluated.…”

Fast Traveling Pneumatic Probes for Turbomachinery Applications

“…In addition to the potentially damaging effect of condensate on the Fig. 7 Cross sectional view of the investigated industrial steam turbine test rig with possible measurement locations E30 and E32 for pneumatic probes [12] Fig. 8 Results of the continuous measuring method recorded with a set of three different measurement parameters compared to a reference measurement from an axial diffuser test rig Fig.…”