Effects of Non-Equilibrium Condensation on Deviation Angle and Performance Losses in Wet Steam Turbines

Abstract

In this paper, effects of non-equilibrium condensation on deviation angle and performance losses of wet stages of steam turbines are investigated. The AUSM-van Leer hybrid scheme is used to solve the two-phase turbulent transonic steam flow around a turbine rotor tip section. The dominant solver of the computational domain is the non-diffusive AUSM scheme (1993), while a smooth transition from AUSM in regions with large gradients (e.g. in and around condensation-and aerodynamic-shocks) to the diffusive scheme by van Leer (1979) guarantees a robust hybrid scheme throughout the domain. The steam is assumed to obey nonequilibrium thermodynamic model, in which abrupt formation of liquid droplets produces a condensation shock. To validate the results, the experimental data by Bakhtar et al. (1995) has been used. It is observed that as a result of condensation, the aerothermodymics of the flow field changes. For example for supersonic wet case with back pressure Pb=30 kPa, the deviation angle and total pressure loss coefficient change by 65% and 200%, respectively, with respect to that in dry case.

Effect of Wet Steam on Aerodynamic Performance of Low-Pressure Exhaust Passage with Last Stage Blade

“…Entropy of the flow field increases during the non-equilibrium condensation due to the thermodynamic losses (Bagheri-Esfe et al 2016b). Then, the condensation of superheated steam in the LSB has important effects on the behavior of the flow field, which not only produces the additional loss due to a deviation from the on-design condition but also increases the stagnation pressure loss and total entropy generation to decrease the turbine efficiency (Bagheri-Esfe et al 2016a). Although an increase in wetness can improve the flow field uniformity and reduce the aerodynamic resistance as wetness enhances, excessive steam humidity also increases the loss in the steam turbine and increases the water droplet erosion on the LSB (Starzmann et al 2013, Grübel et al 2015and Ilieva 2017.…”

Pembuatan Media Pembelajaran Pengujian Koefisien Loss pada Valve di Bidang Mekanik

“…Gambar 2. Sistem Perpipaan Pompa (typical)Dalam aliran fluida secara umum ada dua jenis rugi-rugi aliran, yaitu rugi-rugi karena gesekan fluida dengan dinding saluran yang dilalui fluida alirnya yang disebut dengan rugi-rugi mayor (mayor losses) dan rugi-rugi aliran karena hambatan yang dilalui fluida alir tersebut yang disebut dengan rugi-rugi minor (minor losses)(Esfe, Kermani and Avval, 2016). Rugi-rugi mayor (Mayor losses) merupakan kerugian tinggi tekan (head losses) akibat adanya gesekan fluida yang mengalir dengan dinding saluran yang dilalui fluida alir.…”