Aerodynamic Analysis of Steam Turbine Feed-Heating Steam Extractions

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Budimir Rosic ◽  
Cosimo Maria Mazzoni ◽  
Zoe Bignell
Keyword(s):  
Steam Turbine ◽  
Rotor Blade ◽  
Feed Water ◽  
Steam Turbines ◽  
Flow Angle ◽  
Steam Extraction ◽  
Heating Steam ◽  
Blade Row ◽  
Circumferential Distribution ◽  
Stator Blade

Feed-heating in steam turbines, the use of steam extracted from the turbine to heat the feed-water, is known to raise the plant efficiency and so is included in most steam turbine power plant designs. The steam is extracted through an extraction slot that runs around the casing downstream of a rotor blade row. The slot is connected to a plenum, which runs around the outside of the turbine annulus. Steam flows to the feed-heaters through a pipe connected usually to the bottom of the plenum. The steam extraction is driven by a circumferentially nonuniform pressure gradient in the plenum. This causes the mass flow rate of steam extracted to vary circumferentially, which affects the main passage flow downstream of the extraction point. The flow in the extraction plenum and the influence of the steam extraction on the mainstream aerodynamics is analyzed numerically in this paper. A complete annulus with the extraction slot and plenum together with the downstream stator and rotor blade rows is modeled in this study. The results reveal a highly nonuniform steam extraction around the annulus with the highest extraction rates from the bottom nearest the extraction pipe and the lowest at the top of the annulus. This difference in extraction rates modifies the flow angle and loss circumferential distribution downstream of the stator blade row. This study finds out that the distribution of steam extraction around the annulus and its influence on the main passage flow could be greatly improved by changing the shape and increasing the volume of the extraction slot and plenum.

scholarly journals Application of a Two-Stage Steam Jet Injector Unit for Latent Heat Recovery of a Marine Steam Turbine Propulsion Plant

2021 ◽  
Vol 11 (12) ◽  
pp. 5511
Author(s):  
Szymon Grzesiak ◽  
Andrzej Adamkiewicz
Keyword(s):  
Steam Turbine ◽  
Steam Pressure ◽  
Relative Increase ◽  
Parameters Optimization ◽  
Feed Water ◽  
Water Heating ◽  
Two Stage ◽  
Heating Systems ◽  
Heating Steam ◽  
Numerical Research

The paper presents the results of the numerical research of the steam jet injector applications for the regenerative feed water heating systems of marine steam turbine propulsion plants. The analysis shows that the use of a single injector for a single heat exchanger results in a relative increase in the thermal efficiency of the plant by 0.6–0.9%. The analysis also indicates the legitimacy of the usage of multistage feed water heating systems, which would enable the operating parameters optimization of the injectors. The obtained steam pressure up to the value of 1.8 barA allows for the heating of the feed water up to 110 °C. For higher degrees of feed water heating in the heat exchangers, it is necessary to supply heating steam of higher pressure. Therefore, the usage of two-stage steam jet injector units was considered advisable for the analyses.

Simulation of Unsteady Flows in Intermediate Pressure Steam Turbine with Cutback Stator Blade Row

2020 ◽  
Vol 2020 (0) ◽  
pp. J05102
Author(s):  
Hironori MIYAZAWA ◽  
Akihiro UEMURA ◽  
Takashi FURUSAWA ◽  
Satoru YAMAMOTO ◽  
Shuichi UMEZAWA ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Unsteady Flows ◽  
Intermediate Pressure ◽  
Blade Row ◽  
Pressure Steam ◽  
Stator Blade

Degradation of Aerodynamic Performance of an Intermediate-Pressure Steam Turbine Due to Erosion of Nozzle Guide Vanes and Rotor Blades

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Koichi Yonezawa ◽  
Tomoki Kagayama ◽  
Masahiro Takayasu ◽  
Genki Nakai ◽  
Kazuyasu Sugiyama ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Steam Turbine ◽  
Rotor Blade ◽  
Rotor Blades ◽  
Flow Angle ◽  
Guide Vanes ◽  
Intermediate Pressure ◽  
Pressure Steam ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

Deteriorations of nozzle guide vanes (NGVs) and rotor blades of a steam turbine through a long-time operation usually decrease a thermal efficiency and a power output of the turbine. In this study, influences of blade deformations due to erosion are discussed. Experiments were carried out in order to validate numerical simulations using a commercial software ANSYS-cfx. The numerical results showed acceptable agreements with experimental results. Variation of flow characteristics in the first stage of the intermediate pressure steam turbine is examined using numerical simulations. Geometries of the NGVs and the rotor blades are measured using a 3D scanner during an overhaul. The old NGVs and the rotor blades, which were used in operation, were eroded through the operation. The erosion of the NGVs leaded to increase of the throat area of the nozzle. The numerical results showed that rotor inlet velocity through the old NGVs became smaller and the flow angle of attack to the rotor blade leading edge became smaller. Consequently, the rotor power decreased significantly. Influences of the flow angle of at the rotor inlet were examined by parametric calculations and results showed that the angle of attack was an important parameter to determine the rotor performance. In addition, the influence of the deformation of the rotor blade was examined. The results showed that the degradation of the rotor performance decreased in accordance with the decrease of blade surface area.

Control of Shroud Leakage Loss by Reducing Circumferential Mixing

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Budimir Rosic ◽  
John D. Denton
Keyword(s):  
Significant Proportion ◽  
Tangential Velocity ◽  
Secondary Flows ◽  
Main Stream ◽  
Leakage Flow ◽  
Flow Angle ◽  
Blade Row ◽  
Stator Blade ◽  
The Difference ◽  
Mixing Losses

Shroud leakage flow undergoes little change in the tangential velocity as it passes over the shroud. Mixing due to the difference in tangential velocity between the main stream flow and the leakage flow creates a significant proportion of the total loss associated with shroud leakage flow. The unturned leakage flow also causes negative incidence and intensifies the secondary flows in the downstream blade row. This paper describes the experimental results of a concept to turn the rotor shroud leakage flow in the direction of the main blade passage flow in order to reduce the aerodynamic mixing losses. A three-stage air model turbine with low aspect ratio blading was used in this study. A series of different stationary turning vane geometries placed into the rotor shroud exit cavity downstream of each rotor blade row was tested. A significant improvement in flow angle and loss in the downstream stator blade rows was measured together with an increase in turbine brake efficiency of 0.4 %.

A Comparison Between the Design Point and Near-Stall Performance of an Axial Compressor

1990 ◽  
Vol 112 (1) ◽  
pp. 109-115 ◽  
Author(s):  
N. M. McDougall
Keyword(s):  
Rotor Blade ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
Design Point ◽  
Blade Row ◽  
Clearance Flow ◽  
Stator Blade

Detailed measurements have been made within an axial compressor operating both at design point and near stall. Rotor tip clearance was found to control the performance of the machine by influencing the flow within the rotor blade passages. This was not found to be the case in the stator blade row, where hub clearance was introduced beneath the blade tips. Although the passage flow was observed to be altered dramatically, no significant changes were apparent in the overall pressure rise or stall point. Small tip clearances in the rotor blade row resulted in the formation of corner separations at the hub, where the blade loading was highest. More representative clearances resulted in blockage at the tip due to the increased tip clearance flow. The effects that have been observed emphasize both the three-dimensional nature of the flow within compressor blade passages, and the importance of the flow in the endwall regions in determining the overall compressor performance.

A Comparison Between the Design Point and Near Stall Performance of an Axial Compressor

1989 ◽  
Author(s):  
N. M. McDougall
Keyword(s):  
Rotor Blade ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
Design Point ◽  
Blade Row ◽  
Clearance Flow ◽  
Stator Blade

Detailed measurements have been made within an axial compressor operating both at design point and near stall. Rotor tip clearance was found to control the performance of the machine by influencing the flow within the rotor blade passages. This was not found to be the case in the stator blade row, where hub clearance was introduced beneath the blade tips. Although the passage flow was observed to be altered dramatically, no significant changes were apparent in the overall pressure rise or stall point. Small tip clearances in the rotor blade row resulted in the formation of corner separations at the hub, where the blade loading was highest. More representative clearances resulted in blockage at the tip due to the increased tip clearance flow. The effects which have been observed emphasize both the three dimensional nature of the flow within compressor blade passages, and the importance of the flow in the endwall regions in determining the overall compressor performance.

Blade Row Interaction in a High-Pressure Steam Turbine

2003 ◽  
Vol 125 (1) ◽  
pp. 14-24 ◽  
Author(s):  
V. S. P. Chaluvadi ◽  
A. I. Kalfas ◽  
H. P. Hodson ◽  
H. Ohyama ◽  
E. Watanabe
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Numerical Simulations ◽  
Steam Turbine ◽  
Rotor Blade ◽  
Three Dimensional ◽  
Axial Flow ◽  
Navier Stokes ◽  
Flow Interaction ◽  
Blade Row

This paper presents a study of the three-dimensional flow field within the blade rows of a high-pressure axial flow steam turbine stage. Compound lean angles have been employed to achieve relatively low blade loading for hub and tip sections and so reduce the secondary losses. The flow field is investigated in a low-speed research turbine using pneumatic and hot-wire probes downstream of the blade row. Steady and unsteady numerical simulations were performed using structured 3-D Navier-Stokes solver to further understand the flow field. Agreement between the simulations and the measurements has been found. The unsteady measurements indicate that there is a significant effect of the stator flow interaction in the downstream rotor blade. The transport of the stator viscous flow through the rotor blade row is described. Unsteady numerical simulations were found to be successful in predicting accurately the flow near the secondary flow interaction regions compared to steady simulations. A method to calculate the unsteady loss generated inside the blade row was developed from the unsteady numerical simulations. The contribution of various regions in the blade to the unsteady loss generation was evaluated. This method can assist the designer in identifying and optimizing the features of the flow that are responsible for the majority of the unsteady loss production. An analytical model was developed to quantify this effect for the vortex transport inside the downstream blade.

The Control of Shroud Leakage Loss by Reducing Circumferential Mixing

2006 ◽  
Author(s):  
Budimir Rosic ◽  
John D. Denton
Keyword(s):  
Significant Proportion ◽  
Tangential Velocity ◽  
Secondary Flows ◽  
Main Stream ◽  
Leakage Flow ◽  
Flow Angle ◽  
Blade Row ◽  
Stator Blade ◽  
The Difference ◽  
Mixing Losses

Shroud leakage flow undergoes little change in the tangential velocity as it passes over the shroud. Mixing due to the difference in tangential velocity between the main stream flow and the leakage flow creates a significant proportion of the total loss associated with shroud leakage flow. The unturned leakage flow also causes negative incidence and intensifies the secondary flows in the downstream blade row. This paper describes the experimental results of a concept to turn the rotor shroud leakage flow in the direction of the main blade passage flow in order to reduce the aerodynamic mixing losses. A three-stage air model turbine with low aspect ratio blading was used in this study. A series of different stationary turning vane geometries placed into the rotor shroud exit cavity downstream of each rotor blade row was tested. A significant improvement in flow angle and loss in the downstream stator blade rows was measured together with an increase in turbine brake efficiency of 0.4%.

Numerical Study of Reynolds Number Effects on Steam Turbine Performance

2015 ◽  
Author(s):  
J. H. Cheon ◽  
P. Milčák ◽  
M. Šťastný
Keyword(s):  
Surface Roughness ◽  
Reynolds Number ◽  
Steam Turbine ◽  
Numerical Study ◽  
Measurement Data ◽  
Operating Regime ◽  
Steam Turbines ◽  
Flow Angle ◽  
Turbine Performance ◽  
Reynolds Number Effects

The performance of blade profiles was examined with three linear cascade blades which represent hub, mid-span and tip section using numerical analysis. The Reynolds number was varied from 10,000 to 10,000,000 to capture the operating regime for typical steam turbines. Twelve different levels of surface roughness on the same profile were calculated using the roughness model in ANSYS-CFX. The ratios of surface roughness to chord length are in the range of ks/c = 4.2 × 10–5 ∼ 8.3 × 10−4. The CFD result was compared to Reynolds number correction curves from published literature (AMDC-KO, Aungier, Craig & Cox, Traupel, Sanders and Denton) and available measurement data. Based on these comparisons, a Reynolds number correction curve was properly selected for the estimation of steam turbine performance. Also, it was found that Reynolds number with hydraulically smooth surfaces has little influence on the change in flow angle and roughness does not significantly change outlet flow angle.

Prevention of Steam Turbine Blade Erosion Using Stator Blade Heating

1977 ◽  
Vol 191 (1) ◽  
pp. 355-361 ◽  
Author(s):  
M.S. Akhtar ◽  
J. Black ◽  
M.J.C. Swainston
Keyword(s):  
Steam Turbine ◽  
Turbine Blade ◽  
Economic Effects ◽  
Steam Turbines ◽  
Reduced Pressure ◽  
Full Size ◽  
Basic Physics ◽  
Steam Turbine Blade ◽  
Stator Blade ◽  
Turbine Exhaust

Previous work on the phenomenon of the erosion of the moving blades in steam turbines is reviewed, which has shown that this is due to the accumulation of coarse water on the stationary blades. The basic physics of the accumulation is considered and the conclusion is drawn that this is due to condensation. This can occur even on adiabatic blading, but is expected to be particularly prevalent on blades whose interior is at a reduced pressure (and hence temperature) for suction purposes. Tests are reported on the heating of a single blade mounted in a steam tunnel downstream of a small steam turbine. The turbine exhaust could be arranged to be either wet or superheated. These tests showed that condensation on the blade could be prevented using only small amounts of heating. Methods of applying this system to full size turbines are considered and preliminary economic effects estimated, with encouraging results.

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