scholarly journals The main flow parameters characterising the liquid film suction process on the blade surface in a steam turbine

2020 ◽  
Vol 1675 ◽  
pp. 012029
Author(s):  
V G Gribin ◽  
V A Tishchenko ◽  
V V Popov ◽  
A A Tishchenko ◽  
I Yu Gavrilov ◽  
...  
Keyword(s):  
Liquid Film ◽  
Steam Turbine ◽  
Main Flow ◽  
Blade Surface ◽  
Flow Parameters

Water Droplets Dispersion and Optimization of Water Removal Suction Slot Locations on Stationary Blades in Last-Stage of a 600 MW Steam Turbine

2009 ◽  
Author(s):  
Xinjun Wang ◽  
Pengfei Su ◽  
Luke Chou ◽  
Panlong Guan ◽  
Chunguo Li ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Radial Direction ◽  
Main Flow ◽  
Concave Side ◽  
Water Removal ◽  
Convex Side ◽  
Blade Surface ◽  
Water Droplets ◽  
Last Stage ◽  
Suction Slot

Water droplets dispersion through a stationary cascade channel and their deposition on the blade surface in the last-stage of a 600MW steam turbine have been simulated with CFD software FLUENT. So the deposition on stationary blades along the axial and radial direction was determined. In the experiment, the performance of water removal by suction slots on stationary blades surface was investigated. The results showed that: 12.2% of water at the inlet still existed as droplets, depositing on the concave side of the airfoils in contrast with only 1.6% on the convex side. The volume of the water removed by the suction slots on the concave side was bigger than that on the convex side. The closer the slot position was to the trailing edge, the bigger the volume was. The volume became smaller and then larger with the increase in slot width; the minimum value occurred when slots were about 3.0 mm in width. The bigger suction pressure difference would initiate a bigger volume of water removed by suction slots, but the increase in main flow rate would quickly initiate a smaller volume.

Effects of Design Variations of Rotor Entry Cavity Geometry on Shrouded Steam Turbine Performance

2010 ◽  
Author(s):  
K. G. Barmpalias ◽  
A. I. Kalfas ◽  
R. S. Abhari ◽  
Toshio Hirano ◽  
Naoki Shibukawa
Keyword(s):  
Steam Turbine ◽  
Constant Width ◽  
Main Flow ◽  
Volume Reduction ◽  
Efficiency Gain ◽  
Cavity Volume ◽  
Turbine Performance ◽  
Baseline Case ◽  
Stage Performance ◽  
Stage Efficiency

This paper presents an experimental study of the effect of geometry variations of the rotor entry cavity on shrouded steam turbine performance. A series of experiments was carried out where different configurations of the geometry of the entry cavity were tested. Blade geometry and tip clearance remained unaltered for all cases examined. Interactions between cavity and main flow are carefully investigated and their consequences on shrouded steam turbine stage efficiency are examined. Geometry variations of the entry cavity were installed in a pre-existing ‘baseline’ case of high efficiency. Five different test cases were examined. For the first two of these cases a ring having a constant width of 2mm and 4mm in radial direction is used. The next two cases employ a non-uniform, wavy insert and for the last case a backwards slanted insert is used that covers most of the inlet to cavity area, maintaining a safety distance of 2mm from the downstream rotor. The cases are divided into two groups, based on the same inlet cavity volume. The first group of three cases has a cavity volume reduction of 14% compared to the baseline case, whereas in the second group two cases are examined which maintain a 28% cavity volume reduction compared to the baseline case. Stage performance and flow field data were acquired and analyzed. Strong interactions between cavity and main flow are observed for all cases, not only at the location where the variations were installed. An observed effect can also be seen downstream of the rotor affecting the stage performance. Measurements were performed with the use of miniature probes ensuring minimum blockage effects especially within the cavity, both at rotor inlet as well as downstream of the second rotor. The use of a uniform geometry variation for the inlet rotor cavity in both groups proved to be the best in terms of stage efficiency. Although more complex and non-uniform variations were also used, the simple design of uniform geometry caused the least disturbance in the flow downstream of the 2nd rotor, having at the same time a moderate positive influence at the exit of the 2nd stator. The use of a constant width insert ring (thickness = 2mm) showed an efficiency gain of at least 0.3% from cases with 14% cavity volume reduction, whereas in the cases with 28% cavity volume reduction the use of a uniform ring of 4mm width produced a marginal efficiency gain of 0.1% at the operational point.

scholarly journals Hydrodynamics of Two-Phase Gas-Very Viscous Liquid Flow in Heat Exchange Conditions

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5709
Author(s):  
Krystian Czernek ◽  
Stanisław Witczak
Keyword(s):  
Liquid Film ◽  
Viscous Liquid ◽  
Capillary Waves ◽  
Liquid Cooling ◽  
Two Phase ◽  
Flow Parameters ◽  
Smooth Interface ◽  
Viscous Liquid Film ◽  
Vertical Tubes ◽  
The Impact

This paper presents the results of analyses of the impact of heat transfer conditions on the hydrodynamics of downward co-current annular flow in vertical tubes of very viscous liquid and gas. The research was conducted within the range of gas velocities of 0–30.0 m/s and liquid velocities of 0.001–0.254 m/s, while the viscosity was in the unprecedented range of 0.046–3.5 Pas. The research demonstrates that the volume and nature of the liquid waves with various amplitudes and frequencies arising on the surface of the film are relative to the flow rate and viscosity of the gas phase. At the same time, we found that, under the condition of liquid cooling, an increase in viscosity resulted in the formation of a smooth interface whereas, under the conditions where the liquid is heated at the end of the channel section, a greater number of capillary waves were formed. This research resulted in the development of new dependencies which take into account the influence of selected thermal and flow parameters (including mass fraction) on the values of volumes specific to very viscous liquid film flows. These dependencies improve the accuracy of calculation by 8–10% and are fully applicable to the description of the performance of an apparatus with a hydraulically generated liquid film.

Validation of a 3D RANS Solver With a State Equation of Thermally Perfect and Calorically Imperfect Gas on a Multi-Stage Low-Pressure Steam Turbine Flow

2005 ◽  
Vol 127 (1) ◽  
pp. 83-93 ◽  
Author(s):  
Piotr Lampart ◽  
Andrey Rusanov ◽  
Sergey Yershov ◽  
Stanislaw Marcinkowski ◽  
Andrzej Gardzilewicz
Keyword(s):  
Steam Turbine ◽  
Low Pressure ◽  
State Equation ◽  
Linear Functions ◽  
Perfect Gas ◽  
Specific Heats ◽  
Flow Parameters ◽  
Imperfect Gas ◽  
Multi Stage ◽  
Pressure Steam

A state equation of thermally perfect and calorically imperfect gas is implemented in a 3D RANS solver for turbomachinery flow applications. The specific heats are assumed as linear functions of temperature. The model is validated on a five-stage low-pressure steam turbine. The computational results exhibit the process of expansion in the turbine. The computed and measured distributions of flow parameters in axial gaps downstream of subsequent turbine stages are found to agree reasonably well. It is also shown that the obtained numerical solution gives considerable improvement over the solution based on the thermally and calorically perfect gas model.

Experimental research of flow parameters on the last stage of the steam turbine 1090 MW

2016 ◽  
Author(s):  
Kamil Sedlák ◽  
Michal Hoznedl ◽  
Lukáš Bednář ◽  
Lukáš Mrózek ◽  
Robert Kalista
Keyword(s):  
Steam Turbine ◽  
Experimental Research ◽  
Flow Parameters ◽  
Last Stage

The Deposition of Fog Droplets on Steam Turbine Blades by Turbulent Diffusion

1987 ◽  
Vol 109 (3) ◽  
pp. 429-435 ◽  
Author(s):  
K. K. Yau ◽  
J. B. Young
Keyword(s):  
High Pressure ◽  
Steam Turbine ◽  
Turbulent Diffusion ◽  
Turbine Blades ◽  
Low Pressure ◽  
Surface Velocity ◽  
Reliable Estimate ◽  
Surface Shear Stress ◽  
Blade Surface ◽  
Steam Turbine Blades

A theoretical approach for calculating the rate of deposition of fog droplets on steam turbine blades by turbulent diffusion is described. The theory is similar to that which has proved successful for predicting deposition of small particles in pipe flow and includes a recent correlation for the inertia-moderated regime. A reliable estimate of the blade surface shear stress distribution is required and is obtained by a quasi-three-dimensional inviscid flow calculation to give the blade surface velocity distribution, followed by a two-dimensional boundary layer calculation. The theory has been applied to two representative case studies. The first involves deposition on the final stage blading of the low-pressure cylinder of an operating 500 MW turbine, and the second concerns deposition in a high-pressure, wet steam turbine. Results are presented showing the effect of fog droplet size, surface roughness, and other flow parameters on the deposition rate. A comparison is made between the rates of deposition by diffusional and purely inertial mechanisms. In low-pressure turbines these are of comparable magnitude, but in high-pressure machines diffusional deposition may dominate.

Separation of Water Film From Last Stage Guide Blades of 1000 MW Steam Turbine

2019 ◽  
Author(s):  
Michal Hoznedl ◽  
Ladislav Tajč ◽  
Lukáš Bednář ◽  
Aleš Macálka ◽  
Antonín Živný
Keyword(s):  
Steam Turbine ◽  
Input Data ◽  
Water Film ◽  
Measured Data ◽  
Measuring System ◽  
Blade Surface ◽  
Circumferential Groove ◽  
Water Films ◽  
Stator Blade ◽  
Last Stage

Abstract The paper deals with experimental research of water and steam flow through the grooves in hollow stator blades of the steam turbine last stages with the support of CFD calculations. Also the amount of water sucked by the circumferential groove in the upper limiting wall between the last stage rotor and stator blade was experimentally measured. Measuring took place on a steam turbine with nominal output 1000 MW. With gradual increase of the turbine output it was possible to measure parameters of hollow blades suction for outputs 205, 460, 730, 870 and also 1006 MW. Before starting turbine a complex measuring system was installed consisting of cyclone separator, set of measuring tanks, orifice and pressure sensors and transducers. This measuring system was connected to one hollow stator blade near the horizontal joint. After the measurement the extraction of steam water mixture from this blade was transferred to the condenser via the diffuser chamber in the same way as other non-measured blades. Based on measured data, i.e. the pressure in the hollow stator blade and the flow rate of water captured by the hollow stator blade, it is possible to define the efficiency of suction tract from the viewpoint of total wetness in the inter-stage channel and from the viewpoint of rough liquid phase. The rough liquid phase means water films that flow near the draining grooves and sucked inside to the grooves. The main part of the submitted paper is an analysis of the measured data. Among the analysis results are, besides the flows of rough water phase along the blade surface, the above mentioned efficiency of total wetness suction and of water film suction. For the needs of the analysis there are certain input data, e.g. the value of static pressure and wetness on the blade surface close to the slots that must be defined theoretically using flow path calculations or using CFD methods. In this case, in order to obtain input data, CFD simulations were used when the whole last stage was calculated with the diffuser and exhaust hood. Boundary conditions for CFD were taken from experimental measurements that took place simultaneously with measurement of separated water phase. Numerical simulations were not running for all outputs, but only for three of them — 460, 730 and 1006 MW. For this reason there are no sufficient data for CFD calculations for all outputs and input data of other cases had to be extracted and, based on experience, extrapolated. On the circumferential groove only a part of 30 mm of length was measured, again near the horizontal joint. Due to a short measured groove length it was not possible to obtain the water flow data which would describe suction properties for the whole circumference. The results of experimental measurements provide very important information about the whole suction tract behaviour and its ability to remove liquid water films from the stator blades surface. As very good qualities of the suction tract were confirmed by the measurement, it could be stated that hollow stator blades combined with the circumferential groove on the upper limiting wall is still a suitable technical solution for lowering erosion loading of the last stages. When using a properly dimensioned and correctly working suction system, erosion loading of LSB leading edges on the tip can be lowered by almost a half.

scholarly journals EXPERIMENTAL AND NUMERICAL RESEARCH ON FLOW IN THE LAST STAGE OF 1090MW STEAM TURBINE

2018 ◽  
Vol 20 ◽  
pp. 43-50
Author(s):  
Michal Hoznedl ◽  
Kamil Sedlák
Keyword(s):  
Steam Turbine ◽  
Nuclear Power ◽  
Flow Behavior ◽  
Reynolds Numbers ◽  
Exhaust Hood ◽  
Cfd Simulations ◽  
Flow Parameters ◽  
Numerical Research ◽  
Last Stage ◽  
Good Agreement

The paper deals with experimental and numerical research in the last stage of real 1090MW steam turbine with the last steel blade length 1220mm placed in nuclear power station. The last stage was equipped with twelve static pressure taps. It was also possible to probe in two planes - before and behind the last stage using pneumatic or optical probes. A number of last stage flow parameters were determined at the root and tip wall for nominal turbine output. Among those parameters are static pressures, Mach and Reynolds numbers, last stage reactions and steam wetness. All the directly measured and evaluated flow parameters are taken from locally measured points and that is why even 3D CFD calculation of the whole system - last stage, diffuser and exhaust hood was implemented. Measured and calculated parameters are compared. Especially static pressures are in very good agreement; the only steam wetness has bigger difference due to different measurement position. Locally measured values are enough to estimate the flow behavior of the last stage. On the other hand, the CFD simulations with well determined boundary conditions, meshes and geometry and is effective tool to simulate even very complicated flow structures in the last stage and exhaust hood.

Sign in / Sign up

Export Citation Format

Share Document