Flow Evolution in a One and a Half Axial Steam Turbine Stage Under Different Operating Conditions

2015 ◽  
Author(s):  
Berardo Paradiso ◽  
Alessandro Mora ◽  
Vincenzo Dossena ◽  
Giacomo Gatti ◽  
Andrea Nesti ◽  
...  
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
Mass Flow ◽  
Rotational Speed ◽  
Cfd Simulation ◽  
Guide Vane ◽  
Operating Conditions ◽  
Design Stage ◽  
Inlet Guide Vane ◽  
Turbine Stage

In order to investigate in detail the performance of steam turbine stages the Low Speed Test Rig at Politecnico di Milano has been adapted. The setup consists of a one and an half turbine stage with an inlet guide vane. Two kind of experimental approaches are planned in the project: the first, denominated “performance”, has been carried out by the OGTL department of GE Oil&Gas Florence while, at the same time, Politecnico di Milano performed detailed inter-stage measurements with steady probes and time resolved high response pressure probes. An axial steam turbine stage was tested under several operating conditions in terms of rotational speed, mass flow and inlet angle with the aim to provide the functional curves of the machine together with detailed flow-field measurements. In this paper, a detailed description of the inter-stage flow-field is presented for the most relevant operating condition. Then, a comparison between three different points at the same rotational speed (but different mass flow) is proposed. Finally, the effects of different axial gaps on the overall performance of the stage are discussed. In particular, two different vane-rotor axial gaps have been tested by traversing pressure and temperature probes in three different axial planes. The first measurement plane is located at the first stator exit with the aim to provide details of the inlet swirl angle and 3D flow-field generated by the IGV. In the second plane, located at the rotor exit, the effect of different load conditions on the rotor performance and average flow-field is discussed. Finally, the measurements obtained in the third plane, placed at the second stator exit, are afterwards compared with the one obtained in the first plane, in order to evidence the influence of an unsteady inlet flow-field on the stator behaviour. The aim of the work is to provide very detailed aerodynamic measurements; this large amount of data will be used to validate the results of the CFD simulation carried out in the design stage. In this paper the preliminary findings of the steady flow-field will be presented as the basis for further analysis.

scholarly journals IGV-Rotor Interactions in a 4-Stage Axial Compressor

1998 ◽  
Author(s):  
O. Puetz ◽  
J. Eikelmann ◽  
H. Stoff
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Guide Vane ◽  
Axial Compressor ◽  
Suction Side ◽  
Fast Response ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Mean Values ◽  
Swirl Angle

Detailed experiments have been made in a 4-stage axial compressor of industrial design. The exit flow field of the rotor of the first stage was measured by hot-wire anemometry and fast-response pressure probes under design operating conditions. Tandem inlet guide vanes (IGV) are situated upstream of the first rotor. Flow field results are presented for total pressure, massflux and swirl angle over a closely-spaced grid of probe locations in radial and circumferential directions in the absolute and rotating frame of reference. The tandem inlet guide vane row and stage 1 vane row are positioned peripherally for various settings (clocking). Depending on the peripherical position of IGV and stator 1 the mean values for one rotor pitch varies by 1.5% for mass flow, 1.3° for swirl angle and 8.7% for total pressure. Loss in total pressure at the rotor exit is a minimum, when the IGV row wakes enter the downstream rotor passage at about 1/4 pitch from the suction-side. Blade and vane channels have similar pitchwise spacing.

Effect of Stage Reaction and Shaft Labyrinth Seal in a Stage of an Axial Steam Turbine

2020 ◽  
Author(s):  
Martin Nemec ◽  
Tomas Jelinek ◽  
Jan Uher ◽  
Petr Milcak
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
Mass Flow ◽  
Labyrinth Seal ◽  
Measured Data ◽  
Total Loss ◽  
Relative Mass ◽  
Turbine Stage ◽  
Wide Range ◽  
Stage Performance

Abstract This paper focuses on the influence of shaft labyrinth seal flow on full stage performance. Experimental data are studied, expected design conditions and experimental results are compared and discussed and a losses breakdown for the design procedure is presented. The experimental investigation was performed in VZLU’s air test turbine which is a part of a closed-loop system equipped with a radial compressor. The test turbine configuration simulated the real drum-stage geometry of an axial steam turbine. The geometry of the turbine represents a typical mid-pressure stage of a steam turbine. The configuration of the test rig was adapted in order to easily change the shaft labyrinth seal geometry. The study covered a wide range of seal clearances from very small to extremely large clearances, reaching a maximum relative mass flow approximately 10% of the stator blade flow. Different types of seal feed were also tested to compare internal feed (the flow obtained from the stator flow by the hub-gap just in front of the stator) and external feed realized by additional piping with external regulation. Three stage reactions were tested in this work — Low Reaction, Mid Reaction and Full Reaction. The stator of the stages was the same in all cases, thus the reaction was changed by implementing three different rotor geometries. The influence of the labyrinth seal clearance was investigated by overall performance measurement and by detailed investigation of the flow field. The turbine stage was loaded by a hydraulic dynamometer used for regulating the rotational speed and a flange torquemeter was used to determine the stage efficiency. The total mass flow was measured using an orifice plate. Each seal geometry configuration was calibrated to compute the seal mass flow. The turbine stage and seal were equipped with a number of static pressure taps, and miniature pressure probes were used for measuring the flow field parameters in detail. The discussion of the results is divided into two areas. Firstly, the influence of the degree of reaction on axial steam turbine stage performance in the configuration without the seal flow is presented. Then, a combination of various degrees of reaction is studied as a function of mass flow through the shaft labyrinth seal. The measured data are evaluated by a breakdown of loss sources. The decomposition of the total loss into row losses, leakage losses and mixing losses is highly advantageous. This total loss analysis is carried out for all three stages and both off-design performance and ratios of the shaft seal flow to nozzle blade flow are measured. The post-processing of measured data through this loss breakdown and the comparison with the design is used to validate the design process.

Experimental and Numerical Examinations of a Transonic Compressor-Stage With Casing Treatment

2013 ◽  
Author(s):  
D. Schönweitz ◽  
M. Voges ◽  
G. Goinis ◽  
G. Enders ◽  
E. Johann
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Guide Vane ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Tip Leakage Vortex ◽  
Casing Treatment ◽  
Tip Leakage ◽  
Transonic Compressor

The flow in the blade tip vicinity of the transonic first stage of a multi-stage axial flow compressor with variable inlet guide vane (IGV) and casing treatment (CT) above the rotor is investigated experimentally and numerically with focus on the effects of the CT on flow structures and compressor performance. For the experimental part of this study, conventional performance instrumentation is used to estimate the operating condition of the compressor. Radial distributions of total temperature and total pressure are taken at the leading edges of the stators for comparison with simulations as well as for adjusting the operating conditions of the compressor. The velocity field in the rear part of the first-rotor is determined with Particle Image Velocimetry (PIV) at 90% and 96% radial height using two periscope light sheet probes. The employed PIV setup allows a spatial resolution of 0.7 mm × 0.7mm and thus a similar resolution as the spatial discretization in the simulation. For the numerical part of the study, time-accurate simulations are conducted for the same operating conditions as during experiments. Additional simulations of the same configuration with smooth casing are conducted in order to estimate the effect of the CT on the flow. The examination of PIV measurements and corresponding simulations exposes complex vortical structures originating from the interaction of the rotor bow shock with the IGV trailing edge, CT, IGV wake and the tip leakage vortex. The associated induced velocities together with the general passage flow form a complex flow field with significantly altered blockage compared to a common flow field in the tip vicinity. Position and trajectory of the tip leakage vortex are deduced from interactions between tip leakage vortex and IGV wake / CT. The detailed comparison of the tip region of simulations with and without CT shows that the CT influences pressure rise and flow parameters in a wide radial range due to a radial redistribution of the flow. Correspondingly, a rotor with CT can achieve an increased total pressure rise compared to a rotor with smooth casing, with only minor effects on the efficiency.

Influence of a Cylindrical Exhaust Hood Installation on the Last Stage Rotor Blades of a Low Pressure Model Steam Turbine

2017 ◽  
Author(s):  
Fabian F. Müller ◽  
Markus Schatz ◽  
Damian M. Vogt ◽  
Jens Aschenbruck
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Pressure Measurements ◽  
Exhaust Hood ◽  
Blade Vibration ◽  
Time Resolved ◽  
Vibration Behavior ◽  
Last Stage

The influence of a cylindrical strut shortly downstream of the bladerow on the vibration behavior of the last stage rotor blades of a single stage LP model steam turbine was investigated in the present study. Steam turbine retrofits often result in an increase of turbine size, aiming for more power and higher efficiency. As the existing LP steam turbine exhaust hoods are generally not modified, the last stage rotor blades frequently move closer to installations within the exhaust hood. To capture the influence of such an installation on the flow field characteristics, extensive flow field measurements using pneumatic probes were conducted at the turbine outlet plane. In addition, time-resolved pressure measurements along the casing contour of the diffuser and on the surface of the cylinder were made, aiming for the identification of pressure fluctuations induced by the flow around the installation. Blade vibration behavior was measured at three different operating conditions by means of a tip timing system. Despite the considerable changes in the flow field and its frequency content, no significant impact on blade vibration amplitudes were observed for the investigated case and considered operating conditions. Nevertheless, time-resolved pressure measurements suggest that notable pressure oscillations induced by the vortex shedding can reach the upstream bladerow.

A New Loss and Deviation Model for Axial Compressor Inlet Guide Vanes

2013 ◽  
Author(s):  
Milan Banjac ◽  
Milan V. Petrovic ◽  
Alexander Wiedermann
Keyword(s):  
Guide Vane ◽  
Thickness Distribution ◽  
Axial Compressor ◽  
Algebraic Model ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Viscous Effects ◽  
Through Flow ◽  
Trailing Vortices ◽  
Compressor Inlet

This paper describes a new universal algebraic model for the estimation of flow deflection and losses in axial compressor inlet guide vane devices. The model deals with nominal flow and far-off-design operating conditions in connection with large stagger angle adjustments. The first part of the model considers deflection and losses in 2D cascades, taking into account the main cascade geometry parameters and operating conditions, such as Mach number and stagger adjustment. The second part of the model deals with additional deviation and losses due to secondary flow caused by the endwall viscous effects and by the trailing vortices. The model is developed for NACA65 airfoils, NACA63-A4K6 airfoils and airfoils having an NACA65 thickness distribution on a circular-arc camber line. It is suitable for application in 1D or 2D through-flow calculations for design and analysis cases. The development of the method is based on systematic CFD flow calculations for various cascade geometries and operating parameters. The comparison of correlation results with experimental data for several test cases shows good agreement.

scholarly journals Improvement of Pump Performance at Off-Design Conditions

1985 ◽  
Author(s):  
J. Paulon ◽  
C. Fradin ◽  
J. Poulain
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
Mass Flow ◽  
Flow Characteristic ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Pump Performance ◽  
Wide Range ◽  
Mass Flows ◽  
Design Value

Industrial pumps are generally used in a wide range of operating conditions from almost zero mass flow to mass flows larger than the design value. It has been often noted that the head-mass flow characteristic, at constant speed, presents a negative bump as the mass flow is somewhat smaller than the design mass flows. Flow and mechanical instabilities appear, which are unsafe for the facility. An experimental study has been undertaken in order to analyze and if possible to palliate these difficulties. A detailed flow analyzis has shown strong three dimensional effects and flow separations. From this better knowledge of the flow field, a particular device was designed and a strong attenuation of the negative bump was obtained.

Performance Study of a 1 MW Gas Turbine Using Variable Geometry Compressor and Turbine Blade Cooling

2010 ◽  
Author(s):  
Cleverson Bringhenti ◽  
Jesuino Takachi Tomita ◽  
Joa˜o Roberto Barbosa
Keyword(s):  
Gas Turbine ◽  
Guide Vane ◽  
Turbine Blades ◽  
Axial Flow ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Variable Geometry ◽  
Performance Study ◽  
Turbine Blade Cooling ◽  
Blade Cooling

This work presents the performance study of a 1 MW gas turbine including the effects of blade cooling and compressor variable geometry. The axial flow compressor, with Variable Inlet Guide Vane (VIGV), was designed for this application and its performance maps synthesized using own high technological contents computer programs. The performance study was performed using a specially developed computer program, which is able to numerically simulate gas turbine engines performance with high confidence, in all possible operating conditions. The effects of turbine blades cooling were calculated for different turbine inlet temperatures (TIT) and the influence of the amount of compressor-bled cooling air was studied, aiming at efficiency maximization, for a specified blade life and cooling technology. Details of compressor maps generation, cycle analysis and blade cooling are discussed.

Reduced-Order Modelling of Rotating Stall

2020 ◽  
Author(s):  
Dominik Schlüter ◽  
Robert P. Grewe ◽  
Fabian Wartzek ◽  
Alexander Liefke ◽  
Jan Werner ◽  
...  
Keyword(s):  
Single Cell ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rotational Speed ◽  
Stability Limit ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Transonic Compressor ◽  
Experimental Findings

Abstract Rotating stall is a non-axisymmetric disturbance in axial compressors arising at operating conditions beyond the stability limit of a stage. Although well-known, its driving mechanisms determining the number of stall cells and their rotational speed are still marginally understood. Numerical studies applying full-wheel 3D unsteady RANS calculations require weeks per operating point. This paper quantifies the capability of a more feasible quasi-2D approach to reproduce 3D rotating stall and related sensitivities. The first part of the paper deals with the validation of a numerical baseline the simplified model is compared to in detail. Therefore, 3D computations of a state-of-the-art transonic compressor are conducted. At steady conditions the single-passage RANS CFD matches the experimental results within an error of 1% in total pressure ratio and mass flow rate. At stalled conditions, the full-wheel URANS computation shows the same spiketype disturbance as the experiment. However, the CFD underpredicts the stalling point by approximately 7% in mass flow rate. In deep stall, the computational model correctly forecasts a single-cell rotating stall. The stall cell differs by approximately 21% in rotational speed and 18% in circumferential size from the experimental findings. As the 3D model reflects the compressor behaviour sufficiently accurate, it is considered valid for physical investigations. In the second part of the paper, the validated baseline is reduced in radial direction to a quasi-2D domain only resembling the compressor tip area. Four model variations regarding span-wise location and extent are numerically investigated. As the most promising model matches the 3D flow conditions in the rotor tip region, it correctly yields a single-cell rotating stall. The cell differs by only 7% in circumferential size from the 3D results. Due to the impeded radial migration in the quasi-2D slice, however, the cell exhibits an increased axial extent. It is assumed, that the axial expansion into the adjacent rows causes the difference in cell speed by approximately 24%. Further validation of the reduced model against experimental findings reveals, that it correctly reflects the sensitivity of circumferential cell size to flow coefficient and individual cell speed to compressor shaft speed. As the approach reduced the wall clock time by 92%, it can be used to increase the physical understanding of rotating stall at much lower costs.

Mechanical Design and Testing of a 2.5 MW sCO2 Compressor Loop

2021 ◽  
Author(s):  
Stefan D. Cich ◽  
J. Jeffrey Moore ◽  
Chris Kulhanek ◽  
Meera Day Towler ◽  
Jason Mortzheim
Keyword(s):  
High Efficiency ◽  
Mechanical Design ◽  
Guide Vane ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Inlet Temperature ◽  
Design Changes ◽  
Wide Range ◽  
Inlet Conditions ◽  
Design And Testing

Abstract An enabling technology for a successful deployment of the sCO2 close-loop recompression Brayton cycle is the development of a compressor that can maintain high efficiency for a wide range of inlet conditions due to large variation in properties of CO2 operating near its dome. One solution is to develop an internal actuated variable Inlet Guide Vane (IGV) system that can maintain high efficiency in the main and re-compressor with varying inlet temperature. A compressor for this system has recently been manufactured and tested at various operating conditions to determine its compression efficiency. This compressor was developed with funding from the US DOE Apollo program and industry partners. This paper will focus on the design and testing of the main compressor operating near the CO2 dome. It will look at design challenges that went into some of the decisions for rotor and case construction and how that can affect the mechanical and aerodynamic performance of the compressor. This paper will also go into results from testing at the various operating conditions and how the change in density of CO2 affected rotordynamics and overall performance of the machine. Results will be compared to expected performance and how design changes were implanted to properly counter challenges during testing.

scholarly journals CFD Simulation Research on Agglomeration between Coal-fired Ash Fine Particulate and Atomized Droplets

2020 ◽  
Vol 165 ◽  
pp. 01006
Author(s):  
Yiquan Guo ◽  
Junying Zhang
Keyword(s):  
Power Plant ◽  
Flow Field ◽  
Cfd Simulation ◽  
Negative Impact ◽  
Droplet Diameter ◽  
Temperature Drop ◽  
Operating Conditions ◽  
Gas Temperature ◽  
Simulation Research ◽  
Agglomeration Process

In this paper, a collision model between atomized droplets of agglomeration solution and particles is established. On this basis, the effects of flue gas temperature, atomized droplet diameter and other factors on the particle agglomeration process are studied. In addition, the evaporation model of agglomeration solution in the flue of a power plant is established for the coal-fired unit of power plant. Through CFD software, the variation of flow field velocity, temperature and pressure in the flue is simulated to determine whether the chemical agglomeration technology has negative impact on the actual operating conditions of the power plant. The simulation results show that the velocity and pressure of the flow field in the flue have no obvious change after the agglomerating agent is injected. Besides, the temperature drop of about 7°C. The droplets evaporate completely at a distance of 7-8 m after spraying. The evaporation time of droplets is within 1.6 s.

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