Development of Moisture Loss Models in Steam Turbines

Kawagishi, Hiroyuki; Onoda, Akihiro; Shibukawa, Naoki; Niizeki, Yoshiki

doi:10.1299/kikaib.77.882

Cited by 7 publications

(5 citation statements)

References 12 publications

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“…Therefore, comparison with previous work by other authors may be helpful in reaching a final conclusion. The methods used and results obtained in Laali 6 and Kawagishi et al 7 agree with those in our study, but further investigation is necessary.…”

Section: Discussionsupporting

confidence: 91%

“…Referring to the classification of wetness losses by Moore, 1 Guo, 5 Laali, 6 and Kawagishi, 7 wetness losses are divided into three categories. They are energy loss, mass flow loss and mechanical loss.…”

Section: Wetness Losses Modellingmentioning

confidence: 99%

“…He has reported that the calculated wetness losses are much lower than those calculated by the Baumann rule. Guo et al 5 and Kawagishi et al 7 both calculated the wetness losses in turbine stages by adopting a semianalytical method developed by Young 8 to calculate non-equilibrium wet steam flows. Their results show that the calculated wetness losses correspond well with the experimental data across a wide range of wetness fractions.…”

Section: Introductionmentioning

confidence: 99%

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Quantitative evaluation of wetness losses in steam turbines based on three-dimensional simulations of non-equilibrium condensing flows

Liu²,

Xie

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part A:

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Wet steam flow in steam turbines leads to degraded efficiency and blade erosion in the turbine stages. The Baumann rule, which has been used to predict wetness losses, is increasingly being questioned. More recently, the non-equilibrium condensation model is being increasingly applied to analyse wet steam flow. However, most of the influences caused by wetness losses on the aerodynamics of a wet steam turbine are excluded when this approach is used. Therefore, the efficiency of a wet steam turbine calculated by the non-equilibrium approach does not match the experimentally obtained values. To improve the accuracy of evaluating a wet steam turbine as well as the wetness losses, a quantitative evaluation program of wetness losses has been developed based on the calculation results of wet steam flow with non-equilibrium condensation using the FORTRAN language. Three-dimensional (3D) simulation of the wet steam flow with non-equilibrium condensation in turbine stages is first conducted. Then the 3D results are circumferentially averaged in the meridian plane, which are subsequently used to quantitatively evaluate the wetness losses. The wetness losses are divided into five categories: thermodynamic loss, droplet drag loss, braking loss, capturing loss and centrifuge loss. The wetness losses in the low pressure (LP) cylinder of a fossil steam turbine are calculated. The results show that the thermodynamic loss is mainly generated in the nucleation stage and the last stage of the turbine where non-equilibrium condensation occurs. The droplet drag loss is small in all wet steam stages. The braking loss is the most important component of the wetness losses, except in the nucleation stage. The capturing and centrifuge losses are moderate in the wet steam stages. The total wetness losses in the LP cylinder account for 3.65% of the total output power. This is less than the 5.14% losses predicted by the Baumann rule.

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Section: Discussionsupporting

confidence: 91%

Section: Wetness Losses Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Quantitative evaluation of wetness losses in steam turbines based on three-dimensional simulations of non-equilibrium condensing flows

Liu²,

Xie

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…The massive droplets during the nonequilibrium condensation in the blade cascade not only results in the energy loss but also can impact on the blade surface to cause the erosion issue, which both can influence the efficiency and reliability of the steam turbines [57]. To evaluate the energy loss of the steam turbine, the following equation is employed to quantitatively analyse the condensation loss [58,59].…”

Section: Flow Features In Steam Blade Cascadesmentioning

confidence: 99%

Wet steam flow and condensation loss in turbine blade cascades

Wen

Yang

Ding

et al. 2021

Applied Thermal Engineering

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“…Laali et al 5 developed a wetness losses assessment method based on the through-flow computation of condensing flow. Guo et al 6 and Kawagishi et al 7 proposed wetness losses calculation methods in accordance with the results of non-equilibrium condensation flow computation as obtained through a semi-analytical method. Li et al 8 put forward a wetness losses calculation program based on three-dimensional (3D) computational fluid dynamics (CFD) results; the program can detail the wetness losses in multistage steam turbines.…”

Section: Introductionmentioning

confidence: 86%

Optimisation of a low-pressure multistage steam turbine towards decreasing the wetness losses and aerodynamic losses

Fan

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part A:

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Aerodynamic losses and wetness losses are two crucial factors which contribute to the decrease in the efficiency of wetsteam turbines. In this study, the response surface method is used to optimise the final three stages of a low-pressure steam turbine in consideration of the combined influences of these losses. The selected optimisation variables are the stagger angles and the blade profile stacking lines along the spanwise direction of the stators in these stages. Results show that the pressure balance in the final three stages is changed by optimising the stagger angles, thus facilitating the redistribution of supercooling degrees. As a result, both non-equilibrium thermodynamic loss and droplet diameter are reduced, and the wetness losses are decreased by 20.71%. Moreover, the method of limiting the wetness losses by adjusting the stagger angles of the low-pressure steam turbine is summarised. The optimisation of the profile stacking lines can improve the reaction degree distribution, reduce the boundary layer separation and limit secondary losses. Consequently, the aerodynamic efficiency is enhanced, and the supercooling and the outlet velocity are altered, thereby shrinking the primary and secondary droplets considerably. The aerodynamic losses are reduced by 0.52%, and the wetness losses are further lowered by 9.48%.

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Development of Moisture Loss Models in Steam Turbines

Cited by 7 publications

References 12 publications

Quantitative evaluation of wetness losses in steam turbines based on three-dimensional simulations of non-equilibrium condensing flows

Quantitative evaluation of wetness losses in steam turbines based on three-dimensional simulations of non-equilibrium condensing flows

Wet steam flow and condensation loss in turbine blade cascades

Optimisation of a low-pressure multistage steam turbine towards decreasing the wetness losses and aerodynamic losses

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