Experimental and Numerical Investigations of the Effects of Real Shape Modeling and Non-Equilibrium Condensation Modeling on the Flow Pattern in Steam Turbine

2021 ◽  
Author(s):  
Soichiro Tabata ◽  
Yasuhiro Sasao ◽  
Kiyoshi Segawa
Keyword(s):  
Power Systems ◽  
Flow Pattern ◽  
Steam Turbine ◽  
Shape Modeling ◽  
Computation Model ◽  
Scaled Model ◽  
Ansys Cfx ◽  
High Structural Stability ◽  
Stiffness And Damping ◽  
Non Equilibrium

Abstract This study presents the results of measurements in a scaled model turbine test rig operated at Mitsubishi Hitachi Power Systems, Ltd. In this paper, the flow pattern obtained by traverse measurements is compared with the results of CFD. In order to investigate the flow field in the low pressure steam turbine, the tests are carried out using a test turbine (4 stages) of × 0.33 scale. The velocity and pressure fields are evaluated by traverse measurements. The corresponding CFD are performed by ANSYS CFX. Generally, shroud and stub are used in last stage rotating blades of industrial steam turbine to provide high structural stability by increasing stiffness and damping. In this study, the shroud and stub are modeled in CFD to evaluate the effect on flow pattern. Besides, in order to evaluate the effects of super cooling in blade rows, non-equilibrium condensation is modeled in CFD by ANSYS CFX. The computation model is constructed as accurate reproduction of the scaled model test steam turbine including some steam pipes, supporting sheet metal and the measurement equipment such as traverse pipes and instruments. However, the simple computation model which consists of blade rows with cavities (multi stages) and short diffuser is applied for non-equilibrium condensation calculation due to convergence problems. Comparative evaluation of the test results with the corresponding CFD results showed that the flow patterns predicted by CFD are good. In order to capture the flow pattern characteristics by CFD, it is necessary to consider both real shape modeling and non-equilibrium condensation modeling.

Experimental and Numerical Investigations of Steam Turbine Exhaust Hood Flow Field With Two Types of Diffusers

2019 ◽  
Author(s):  
Soichiro Tabata ◽  
Hisataka Fukushima ◽  
Kiyoshi Segawa ◽  
Koji Ishibashi ◽  
Yoshihiro Kuwamura ◽  
...  
Keyword(s):  
Flow Field ◽  
Flow Pattern ◽  
Steam Turbine ◽  
Three Dimensional ◽  
Internal Flow ◽  
Exhaust Hood ◽  
Scaled Model ◽  
Last Stage ◽  
Verification Test ◽  
Lp Turbine

Abstract The exhaust hood performance of LP turbine plays an important role in the efficiency of steam turbine. By improving the exhaust performance, the kinetic energy of the last stage rotating blades can be converted to the potential energy and it becomes possible to improve the turbine efficiency. However, the flow field in the diffuser is closely related to the flow pattern of the last stage rotating blade, and the flow field inside the exhaust chamber afterward has a complicated three dimensional flow field. Therefore, in this study, it conducted a scaled model steam turbine test using two types of diffusers and CFD, and evaluated exhaust performance and flow pattern. The verification test was carried out using a test turbine (4 stages) of × 0.33 scale, the velocity field and the pressure field were evaluated by traverse and the wall pressure measurements. The corresponding CFD was calculated by ANSYS CFX. All four stages of blades and seals, exhaust chambers were accurately modeled. Due to the detailed CFD, the internal flow of the exhaust chamber exhibiting complicated three-dimensionality was visualized and the flow pattern was evaluated. The verification test results and the corresponding CFD results were compared and evaluated, and it has been found that the overall performance predicted by CFD is well showing the verification test result. Therefore, it has been found that CFD can help to understand the internal flow of the exhaust chamber exhibiting complex three-dimensional characteristics.

Non-Equilibrium Homogeneously Condensing Flow Analyses as Design Tools for Steam Turbines

2002 ◽  
Author(s):  
Shigeki Senoo ◽  
Yoshio Shikano
Keyword(s):  
Flow Pattern ◽  
Steam Turbine ◽  
Three Dimensional ◽  
Design Stage ◽  
Steam Turbines ◽  
Three Dimensional Flow ◽  
Pattern Design ◽  
Flow Calculation ◽  
Dimensional Flow ◽  
Non Equilibrium

In order to get the details of flow fields in steam turbines, three-dimensional turbulent flow calculations are useful. However in a design procedure, three-dimensional flow calculations are only possible in the last design stage, because they need in-depth boundary conditions of both geometries and flows. At such a late time in the procedure, it is difficult to go back and change main design parameters, such as flow area and stage load. Both three-dimensional flow patterns and non-equilibrium condensation caused by rapid expansions of steam have important roles with respect to steam turbine performance particularly in low-pressure sections. The steam turbine internal efficiency can be improved by taking account of these effects in the early design stage, especially in flow pattern design. This paper describes a multi-stage through-flow calculation technique including both three-dimensional flow efffects and phase changes from vapour to small droplets. To compute the high-speed two phase steam flow, a flux-splitting procedure including non-equilibrium homogeneously condensation is introduced. Three-dimensional blade forces are calculated by using angles of both blade camber and radial lean. The blade camber lines can be decided without in-depth blade geometries. Therefore this computational technique is applicable in the flow pattern design. The calculation results agree well with fully three-dimensional flow calculation and the calculation can predict supersaturating states and Wilson lines which are defined as the maximum supercooling.

scholarly journals Preliminary Study on a Reduced Scaled Model Regarding the Air Diffusion inside a Crew Quarter on Board of the ISS

2018 ◽  
Vol 32 ◽  
pp. 01015
Author(s):  
Mihnea Sandu ◽  
Ilinca Nastase ◽  
Florin Bode ◽  
CristianaVerona Croitoru ◽  
Laurentiu Tacutu
Keyword(s):  
Flow Pattern ◽  
Ventilation System ◽  
Measurement Techniques ◽  
Space Station ◽  
Similarity Criteria ◽  
Scaled Model ◽  
Velocity Magnitude ◽  
Piv Measurement ◽  
Geometrical Scale ◽  
Air Diffusion

The paper focus on the air quality inside the Crew Quarters on board of the International Space Station. Several issues to improve were recorded by NASA and ESA and most important of them are the following: noise level reduction, CO2 accumulation reduction and dust accumulation reduction. The study in this paper is centred on a reduced scaled model used to provide simulations related to the air diffusion inside the CQ. It is obvious that a new ventilation system is required to achieve the three issues mentioned above, and the solutions obtained by means of numerical simulation need to be validated by experimental approach. First of all we have built a reduced scaled physical model to simulate the flow pattern inside the CQ and the equipment inside the CQ has been reproduced using a geometrical scale ratio. The flow pattern was considered isothermal and incompressible. The similarity criteria used was the Reynolds number to characterize the flow pattern and the length scale was set at value 1/4. Water has been used inside the model to simulate air. Velocity magnitude vectors have been obtained using PIV measurement techniques.

Vortex Tube Applications in Micro-Power Generation

2002 ◽  
Author(s):  
Selin Arslan ◽  
Bojan Mitrovic ◽  
Michael R. Muller
Keyword(s):  
Pressure Drop ◽  
Power Systems ◽  
Steam Turbine ◽  
Vortex Tube ◽  
Low Pressure ◽  
Total Efficiency ◽  
Pressure Drops ◽  
Large Pressure ◽  
Micro Power ◽  
Vortex Tubes

The purpose of this paper is to study vortex tube performance characteristics and the use of vortex tubes to increase the total efficiency of power systems, especially micropower systems. A vortex tube is a device in which compressed air is made to swirl and separate into two low-pressure streams, one with higher temperature than the entry and the other lower. The lack of moving parts and electricity make the vortex tube attractive for a number of specialized applications where simplicity, robustness and reliability are desired. Vortex tubes are currently used for industrial cooling applications, separation technologies, and chemical analysis. It is well known that the temperature difference between the hot and cold sides of the vortex tube scales with the pressure drop. Also, at any pressure drop, the temperatures and flow rates are dependent on the flow fractions between the hot and cold sides. Data is available for large pressure drops, but this paper presents experimental results at low-pressure drops optimizing the operational modes for various applications. The micro-power systems under consideration include micro-turbines, which evolved out of automotive turbocharger technology. The use of vortex tubes in power systems has received some attention but the use of both the hot and cold streams has never been considered. In this work, we consider such dual use. As an example of an application, the vortex tube is considered in conjunction with a heat recovery steam generator (HRSG). The vortex tube splits the turbine exhaust flow into hotter and cooler streams. The cooler stream is still hot enough to supply all needed heat in the economizer section, leaving the hotter stream to increase the exit temperature from the superheater. In this way both the air leaving the HRSG and going to the steam turbine will have an increased enthalpy and cycle efficiencies are improved. In addition, steam turbine exit quality is increased.

Numerical Investigation of the Impact of Part-Span Connectors on Aero-Thermodynamics in a Low Pressure Industrial Steam Turbine

2014 ◽  
Author(s):  
M. Häfele ◽  
J. Starzmann ◽  
M. Grübel ◽  
M. Schatz ◽  
D. M. Vogt ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Numerical Study ◽  
Three Dimensional ◽  
Measurement Data ◽  
Cross Flow ◽  
Low Pressure ◽  
Wet Steam ◽  
Flow Vortex ◽  
The Impact ◽  
Non Equilibrium

A numerical study on the flow in a three stage low pressure industrial steam turbine with conical friction bolts in the last stage and lacing wires in the penultimate stage is presented and analyzed. Structured high-resolution hexahedral meshes are used for all three stages and the meshing methodology is shown for the rotor with friction bolts and blade reinforcements. Modern three-dimensional CFD with a non-equilibrium wet steam model is used to examine the aero-thermodynamic effects of the part-span connectors. A performance assessment of the coupled blades at part load, design and overload condition is presented and compared with measurement data from an industrial steam turbine test rig. Detailed flow field analyses and a comparison of blade loading between configurations with and without part-span connectors are presented in this paper. The results show significant interaction of the cross flow vortex along the part-span connector with the blade passage flow causing aerodynamic losses. This is the first time that part-span connectors are being analyzed using a non-equilibrium wet steam model. It is shown that additional wetness losses are induced by these elements.

The Influence of Non-Equilibrium Wet Steam Effects on the Aeroelastic Properties of a Turbine Blade Row

2016 ◽  
Author(s):  
Christopher Fuhrer ◽  
Marius Grübel ◽  
Damian M. Vogt ◽  
Paul Petrie-Repar
Keyword(s):  
Steam Turbine ◽  
Turbine Blade ◽  
Ideal Gas ◽  
Test Case ◽  
Steam Turbines ◽  
Wet Steam ◽  
Flow Conditions ◽  
Flutter Analysis ◽  
Last Stage ◽  
Non Equilibrium

Turbine blade flutter is a concern for the manufacturers of steam turbines. Typically, the length of last stage blades of large steam turbines is over one meter. These long blades are susceptible to flutter because of their low structural frequency and supersonic tip speeds with oblique shocks and their reflections. Although steam condensation has usually occurred by the last stage, ideal gas is mostly assumed when performing flutter analysis for steam turbines. The results of a flutter analysis of a 2D steam turbine test case which examine the influence of non-equilibrium wet steam are presented. The geometry and flow conditions of the test case are supposed to be similar to the flow near the tip in a steam turbine as this is where most of the unsteady aerodynamic work contributing to flutter is done. The unsteady flow simulations required for the flutter analysis are performed by ANSYS CFX. Three fluid models are examined: ideal gas, equilibrium wet steam (EQS) and non-equilibrium wet steam (NES), of which NES reflects the reality most. Previous studies have shown that a good agreement between ideal gas and EQS simulations can be achieved if the prescribed ratio of specific heats is equal to the equilibrium polytropic index of the wet steam flow through the turbine. In this paper the results of a flutter analysis are presented for the 2D test case at flow conditions with wet steam at the inlet. The investigated plunge mode normal to chord is similar to a bending mode around the turbine axis for a freestanding blade in 3D. The influence of the overall wetness fraction and the size of the water droplets at the inlet are examined. The results show an increase of aerodynamic damping for all investigated interblade phase angles with a reduction of droplet size. The influence of the wetness fraction is in comparison of less importance.

Towards Scale Resolving Computations of Condensing Wet Steam Flows

2019 ◽  
Author(s):  
Pascal Post ◽  
Marwick Sembritzky ◽  
Francesca di Mare
Keyword(s):  
Steam Turbine ◽  
Two Phase Flow ◽  
Ideal Gas ◽  
Phase Flow ◽  
Wet Steam ◽  
Two Phase ◽  
Upwind Schemes ◽  
Computational Speed ◽  
Euler Model ◽  
Non Equilibrium

Abstract In this paper we present a turbomachinery density-based CFD solver optimized for CPUs as well as GPUs, which accounts for complex thermodynamics including non-equilibrium condensation and two-phase flow, making extensive use of tabulation techniques. The two-phase flow is treated by means of the mono-dispersed Source-Term Euler-Euler model. The non-equilibrium wet-steam model is validated in classical nozzle test cases and its application in turbomachinery configuration is demonstrated in a well-documented steam turbine cascade in the context of classic RANS modeling. Finally, the LES-solver performance and scalability, together with its accuracy, are assessed and discussed on the basis of the well-known and theoretically relevant experiment by Comte-Bellot and Corrsin. For both, standard RANS computations, where an upwind schemes has been adopted, as well as for the LES computations, where a central scheme in skew-symmetric form has been employed, the solver shows remarkable computational speed and accuracy for non-ideal gas applications, rendering it suitable for more complex LES computations in steam turbine flows.

NUMERICAL MODELING OF A VERY LARGE CRUDE OIL CARRIER USING ANSYS CFX: A CASE STUDY OF SALINA

2021 ◽  
Vol 161 (A4) ◽  
Author(s):  
H Hakimzadeh ◽  
M Torabi Azad ◽  
M A Badri ◽  
F Azarsina ◽  
M Ezam
Keyword(s):  
Numerical Simulation ◽  
Crude Oil ◽  
Drag Force ◽  
Performance Monitoring ◽  
Numerical Models ◽  
Frictional Resistance ◽  
Simulation Method ◽  
Scaled Model ◽  
Ansys Cfx ◽  
The Difference

Specification of the frictional resistance values of tankers is the first step in managing their fuel consumption. Drag force of a very large crude oil carrier has been calculated using the numerical simulation method. With application of the ANSYS CFX software, the scaled model of the mentioned tanker with the length of 2.74 meters, width of 0.5 meters, draft of 0.17 meters was used for numerical simulation of the drag force in the tanker. Furthermore, the numerical solution of the drag force of the model was performed for 5 different speeds ranging from 0.65 to 0.85m/s. Based on the validations carried out, with mean drafts of 8 and 16.5cm, the difference between the results of the experimental and numerical models at low speeds was about 7%. However, the difference was observed to be up to 15% at higher Froude numbers. The results of the present study with respect to the SALINA are based on the method presented in ISO 19030 standard addressing the performance monitoring during vessel servicing.

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