Nucleation Phenomena in Flowing High-Pressure Steam: Experimental Results

Author(s):  
F Bakhtar ◽  
K Zidi

The paper describes the results of an experimental investigation of limiting supersaturation in high-pressure steam. It follows an earlier investigation and to avoid the uncertainties associated with leakage past sliding profiles, the test section has been redesigned and the measurements taken with fixed nozzles. Three convergent-divergent nozzles with nominal rates of expansion of 3000, 5000 and 10000 per second have been used and the inlet stagnation pressures cover the range 25–35 bar. The data consist mainly of axial pressure distributions but some droplet measurements have also been recorded.

Author(s):  
Minel J. Braun ◽  
Hazel M. Pierson ◽  
Hongmin Li

Finger seals (FS) are compliant seal configurations. Unlike brush seals, they exhibit hydrodynamic lifting capabilities which allow non-contact sealing between stationary and rotating members. The compliance combined with the non-contacting feature allows both axial and radial adjustment of the seal to the rotor excursions without endangering the integrity of the former. The embodiment of a two-layer finger seal with high pressure (1c) and low pressure (1b) laminates is shown in Figure1. In this paper we shall analyze the thermo-hydraulic and mechanical performance (axial and radial deformations and displacements) of a representative repetitive cell that contains four high pressure and four low-pressure fingers arranged axially in a staggered configuration, and subject to rotation and an axial pressure drop. We shall also present experimental results pertaining to the seal deformation under axial pressure differential and rotation.


Author(s):  
Juri Bellucci ◽  
Federica Sazzini ◽  
Filippo Rubechini ◽  
Andrea Arnone ◽  
Lorenzo Arcangeli ◽  
...  

This paper focuses on the use of the CFD for improving a steam turbine preliminary design tool. Three-dimensional RANS analyses were carried out in order to independently investigate the effects of profile, secondary flow and tip clearance losses, on the efficiency of two high-pressure steam turbine stages. The parametric study included geometrical features such as stagger angle, aspect ratio and radius ratio, and was conducted for a wide range of flow coefficients to cover the whole operating envelope. The results are reported in terms of stage performance curves, enthalpy loss coefficients and span-wise distribution of the blade-to-blade exit angles. A detailed discussion of these results is provided in order to highlight the different aerodynamic behavior of the two geometries. Once the analysis was concluded, the tuning of a preliminary steam turbine design tool was carried out, based on a correlative approach. Due to the lack of a large set of experimental data, the information obtained from the post-processing of the CFD computations were applied to update the current correlations, in order to improve the accuracy of the efficiency evaluation for both stages. Finally, the predictions of the tuned preliminary design tool were compared with the results of the CFD computations, in terms of stage efficiency, in a broad range of flow coefficients and in different real machine layouts.


2001 ◽  
Vol 71 (12) ◽  
pp. 1063-1067 ◽  
Author(s):  
Jui-Chin Chen ◽  
Wei-Hua Yao ◽  
Chien-Hsin Chen ◽  
Cheng-Chi Chen

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