Aerodynamic experimental measurements and numerical simulations carried out on a model of a high-pressure valve assembly used for a nozzle governing of a turbine with 135 MW output are described in this paper. Aim of the study is to investigate effects of control valve’s strainers on pressure losses and unsteadiness in the flow field thus its effect to undesirable flow fluctuations which can lead to operation reliability issues. Measurements were carried out in the Aerodynamic laboratory of the Institute of Thermomechanics in Czech Academy of Sciences (CAS) where an aerodynamic tunnel is installed. Numerical simulations were carried out in the Doosan Skoda Power (DSP) Company using the ANSYS software tools. The experimental model consists of one of two identical parts of the real valve assembly. It means it consists of an inlet pipeline, a stop valve, a valve chamber with two independent control valves, its diffusers and outlet pipelines. The numerical model consists of both assembly parts and includes also an A-wheel control stage in order to simulate the real turbine operation points as real as possible. The different lifts of the main cone in each control valve for its useful combinations were investigated. Results were evaluated on the model with control valve´s strainers, which were historically used in order to stabilize the flow, and without them. In order to measure pressure losses, the wall static pressure taps evenly distributed around pipelines and valve diffuser´s circumference were installed at different positions in the model. In order to measure pressure fluctuations, Kulite fast response pressure transducers mounted in control valve´s diffuser throats were used. The results of the experimental measurement were compared with the numerical results in the form of pressure losses prediction. From the pressure fluctuation evaluation, it was found out where and for which conditions a danger of a flow instabilities appearance could appear. It can be concluded that there is a border, in terms of operating conditions, where the flow field starts to be unstable and this border is different dependent of the fact whether the control valve´s strainers are used or not. Therefore, the areas of save and danger operation reliability can be predicted. The influence of the control valve´s strainers on the maximal amplitude of periodic fluctuations appears only for the cases when valves are very overload. For normal operating conditions, there is no difference. As a result, the control valve´s strainers do not have to be used in standard applications of valve assemblies. Furthermore, a loss model for valve pressure loss estimation could be updated. Therefore, a pressure loss should be predicted with a sufficient accuracy for each new turbine bid when a similar valve assembly is going to be used. To sum up, by being able to predict the pressure loss and knowing that the valves are reliable are safe for required operating conditions, increasingly demanding customer needs can be fulfilled for each future project.


Experimental and Numerical Study on Pressure Losses and Flow Fluctuations in a High-Pressure Valve Assembly of Steam Turbine Governing System

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

Turbo Expo - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.