Abstract Heat transfer and vacuum in condenser are influenced by the aerodynamic performance of steam tur- bine exhaust hood. The current research on exhaust hood is mainly focused on analyzing flow loss and optimal d...Abstract Heat transfer and vacuum in condenser are influenced by the aerodynamic performance of steam tur- bine exhaust hood. The current research on exhaust hood is mainly focused on analyzing flow loss and optimal design of its structure without consideration of the wet steam condensing flow and the exhaust hood coupled with the front and rear parts. To better understand the aerodynamic performance influenced by the tilt angle of flow guide inside a diffuser, taking a 600 MW steam turbine as an example, a numerical simulator CFX is adopted to solve compressible three-dimensional （3D） Reynolds time-aver- aged N-S equations and standard k-e turbulence model. And the exhaust hood flow field influenced by different tilt angles of flow guide is investigated with consideration of the wet steam condensing flow and the exhaust hood coupled with the last stage blades and the condenser throat. The result shows that the total pressure loss coefficient and the static pressure recovery coefficient of exhaust hood change regularly and monotonously with the gradual increase of tilt angle of flow guide. When the tilt angle of flow guide is within the range of 30~ to 40~, the static pressure recovery coefficient is in the range of 15.27% to 17.03% and the total pressure loss coefficient drops to approximately 51%, the aerodynamic performance of exhaust hood is significantly improved. And the effectiveenthalpy drop in steam turbine increases by 0.228% to 0.274%. It is feasible to obtain a reasonable title angle of flow guide by the method of coupling the last stage and the condenser throat to exhaust hood in combination of the wet steam model, which provides a practical guidance to flow guide transformation and optimal design in exhaust hood.展开更多
The flow in the exhaust hood of a condensing steam turbine depends to a considerable extent on the inlet swirl of the flow which changes in tandem with the volumetric flow of steam through the last stage. This study g...The flow in the exhaust hood of a condensing steam turbine depends to a considerable extent on the inlet swirl of the flow which changes in tandem with the volumetric flow of steam through the last stage. This study gives a description of experiments which were carried out on the exhaust hood of a 500 MW steam turbine under various conditions, e.g. when there is rated power, when there is an idle run, or when there are various pressures in the condenser. The flow in a model exhaust hood was investigated by means of CFD methods. Computations were performed with the help of the FLUENT 5 code which is based on solving the Navier-Stokes equations while taking the RSM and LES models of turbulence into consideration. The results of the computations are in full conformity with the experiments.展开更多
The purpose of this paper is to improve the aerodynamic performances of the last stage turbine and the exhaust hood of a 600MW steam turbine under design and off design conditions. During operation, strong flow intera...The purpose of this paper is to improve the aerodynamic performances of the last stage turbine and the exhaust hood of a 600MW steam turbine under design and off design conditions. During operation, strong flow interactions between the turbine and the exhaust hood impose influences on the flow behavior in the hood and lead to the unsatisfactory aerodynamic performance of the turbine and exhaust hood. So the exhaust hood has the potential to be improved in terms of aerodynamic efficiency. Considering the flow interactions between the turbine and the exhaust hood, the profiles of the diffuser end-wall were optimized. The coupled model turbine and model exhaust hood calculations and experiments were carried out to validate the effects of the optimization. Model experiments show that the design modifications resulted in a substantial increase in the overall pressure recovery coefficient. The flow and aerodynamic performances of the full-scale last stage turbine and full-scale exhaust hood were simulated to explore the flow physics alterations to the modification of diffuser geometry. The wet steam was selected as the flow medium. The actual flow fields trader different operation conditions were analyzed.展开更多
The idea of steam injection gas turbine cycle system is to inject steam generated by gas turbine exhaust gas into the gas turbine itself in order to raise its specific output and efficiency. The main advantages of thi...The idea of steam injection gas turbine cycle system is to inject steam generated by gas turbine exhaust gas into the gas turbine itself in order to raise its specific output and efficiency. The main advantages of this cycle are: the part load performance is excellent when it is used for cogeneration, the system is rather simple compared with conventional combined cycles; its drawback is the consumption of certain amount of make-up water, although the quantity is not very large and the expenditure is not expensive.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51576036,51476192)Science and Technology Development Planning Foundation of Jilin Province of China(Grant No.20140204040SF)
文摘Abstract Heat transfer and vacuum in condenser are influenced by the aerodynamic performance of steam tur- bine exhaust hood. The current research on exhaust hood is mainly focused on analyzing flow loss and optimal design of its structure without consideration of the wet steam condensing flow and the exhaust hood coupled with the front and rear parts. To better understand the aerodynamic performance influenced by the tilt angle of flow guide inside a diffuser, taking a 600 MW steam turbine as an example, a numerical simulator CFX is adopted to solve compressible three-dimensional （3D） Reynolds time-aver- aged N-S equations and standard k-e turbulence model. And the exhaust hood flow field influenced by different tilt angles of flow guide is investigated with consideration of the wet steam condensing flow and the exhaust hood coupled with the last stage blades and the condenser throat. The result shows that the total pressure loss coefficient and the static pressure recovery coefficient of exhaust hood change regularly and monotonously with the gradual increase of tilt angle of flow guide. When the tilt angle of flow guide is within the range of 30~ to 40~, the static pressure recovery coefficient is in the range of 15.27% to 17.03% and the total pressure loss coefficient drops to approximately 51%, the aerodynamic performance of exhaust hood is significantly improved. And the effectiveenthalpy drop in steam turbine increases by 0.228% to 0.274%. It is feasible to obtain a reasonable title angle of flow guide by the method of coupling the last stage and the condenser throat to exhaust hood in combination of the wet steam model, which provides a practical guidance to flow guide transformation and optimal design in exhaust hood.
基金They would also like to thank the Grant Agency of the Czech Republic for the support they received from the No. 101/9910625 an
文摘The flow in the exhaust hood of a condensing steam turbine depends to a considerable extent on the inlet swirl of the flow which changes in tandem with the volumetric flow of steam through the last stage. This study gives a description of experiments which were carried out on the exhaust hood of a 500 MW steam turbine under various conditions, e.g. when there is rated power, when there is an idle run, or when there are various pressures in the condenser. The flow in a model exhaust hood was investigated by means of CFD methods. Computations were performed with the help of the FLUENT 5 code which is based on solving the Navier-Stokes equations while taking the RSM and LES models of turbulence into consideration. The results of the computations are in full conformity with the experiments.
基金financially supported by the National Natural Science Foundation of China(Grant No.51336007)
文摘The purpose of this paper is to improve the aerodynamic performances of the last stage turbine and the exhaust hood of a 600MW steam turbine under design and off design conditions. During operation, strong flow interactions between the turbine and the exhaust hood impose influences on the flow behavior in the hood and lead to the unsatisfactory aerodynamic performance of the turbine and exhaust hood. So the exhaust hood has the potential to be improved in terms of aerodynamic efficiency. Considering the flow interactions between the turbine and the exhaust hood, the profiles of the diffuser end-wall were optimized. The coupled model turbine and model exhaust hood calculations and experiments were carried out to validate the effects of the optimization. Model experiments show that the design modifications resulted in a substantial increase in the overall pressure recovery coefficient. The flow and aerodynamic performances of the full-scale last stage turbine and full-scale exhaust hood were simulated to explore the flow physics alterations to the modification of diffuser geometry. The wet steam was selected as the flow medium. The actual flow fields trader different operation conditions were analyzed.
基金Project supported by the Science Fund of Academia Sinica
文摘The idea of steam injection gas turbine cycle system is to inject steam generated by gas turbine exhaust gas into the gas turbine itself in order to raise its specific output and efficiency. The main advantages of this cycle are: the part load performance is excellent when it is used for cogeneration, the system is rather simple compared with conventional combined cycles; its drawback is the consumption of certain amount of make-up water, although the quantity is not very large and the expenditure is not expensive.
