Inlet Flux Influence to Aerodynamic Performance of Steam Turbine Vane Cascade

This paper addresses the issue of aerodynamic performance of a novel 3D leading edge modification to a reference vane. An analysis of tubercles found in nature and some engineering applications was used to synthesize new leading edge geometry. Three variations of the reference low pressure turbine vane were obtained by changing the characteristic parameters of the tubercles. Shock structure, surface flow visualization and total pressure measurements were made through experiments in a cascade rig, as well as through computational fluid dynamics. The tests were carried out at design zero incidence and off-design ±10-deg and ±5-deg incidences. The performance of the new 3D leading edge geometries was compared against the reference vane. Some leading edge tubercle configurations were effective at decreasing total pressure losses at positive inlet incidence angles. Numerical results supplemented experimental results.

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Measurements and Predictions of Surface Roughness Effects on the Turbine Vane Aerodynamics

Volume 6: Turbo Expo 2003, Parts A and B ◽

10.1115/gt2003-38580 ◽

2003 ◽

Cited By ~ 23

Author(s):

R. J. Boyle ◽

R. G. Senyitko

Keyword(s):

Surface Roughness ◽

Turbulence Models ◽

Reynolds Numbers ◽

Aerodynamic Performance ◽

Navier Stokes ◽

Two Dimensional ◽

Roughness Effects ◽

Linear Cascade ◽

Wide Range ◽

Turbine Vane

The aerodynamic performance of a turbine vane was measured in a linear cascade. These measurements were conducted for exit-true chord Reynolds numbers between 150,000 and 1,800,000. The vane surface rms roughness-to-true chord ratio was approximately 2 × 10−4. Measurements were made for exit Mach numbers between 0.3 and 0.9 to achieve different loading distributions. Measurements were made at three different inlet turbulence levels. High and intermediate turbulence levels were generated using two different blown grids. The turbulence was low when no grid was present. The wide range of Reynolds numbers was chosen so that, at the lower Reynolds numbers the rough surfaces would be hydraulically smooth. The primary purpose of the tests was to provide data to verify CFD predictions of surface roughness effects on aerodynamic performance. Data comparisons are made using a two-dimensional Navier-Stokes analysis. Both two-equation and algebraic roughness turbulence models were used. A model is proposed to account for the increase in loss due to roughness as the Reynolds number increases.

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Effect of Snubbers and Lacing Wire on Aerodynamic Performance of Last Stage Steam Turbine

Volume 1: Compressors, Fans, and Pumps; Turbines; Heat Transfer; Structures and Dynamics ◽

10.1115/gtindia2019-2509 ◽

2019 ◽

Author(s):

P. Sreekumar ◽

Mahesh K. Varpe

Keyword(s):

Aspect Ratio ◽

Steam Turbine ◽

Aerodynamic Performance ◽

Base Line ◽

Performance Loss ◽

Performance Requirements ◽

Last Stage ◽

Lp Turbine ◽

The Impact ◽

Sensitive Behavior

Abstract The aerodynamics design of a steam turbine stage is an agreement between the performance requirements and the mechanical limitations. The design of last stage of the low-pressure steam (LP) turbine is the most complicated because of the blade twist and a tapered blade along with high aspect ratio due to the sharp increase in the specific volume of the steam during its expansion. The choice of higher aspect ratio for increased power generation makes the turbine blade experience the vibration due to lower modal frequencies which depend on the running speed of a turbine. Therefore, the sensitive behavior of these blades is reduced by damping the blade vibrations which comes with the penalty of aerodynamic performance. The investigation reported here discusses the impact of lacing wire and snubber mounted at 70% blade span. Both, the lacing wire and snubber aligned parallel to the rotor axis deteriorates the efficiency by 0.75% and 1.7% respectively. However, the aerodynamically shaped snubber aligned with the streamline direction recovers the efficiency to that of base line. The mechanism of streamwise aligned snubber in containing aerodynamic performance loss is quite interesting and is being discussed.

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Effect of Material Damping of Steam Turbine Vane on Flutter Suppression

Volume 7: Structures and Dynamics, Parts A and B ◽

10.1115/gt2012-68089 ◽

2012 ◽

Cited By ~ 2

Author(s):

Yasutomo Kaneko ◽

Kazushi Mori ◽

Hiroharu Ohyama

Keyword(s):

Steam Turbine ◽

Aerodynamic Force ◽

Working Fluid ◽

Material Damping ◽

Element Analysis ◽

Flutter Suppression ◽

Aerodynamic Damping ◽

Turbine Vane ◽

3D Fea ◽

The Stability

The vane used in a low pressure end of steam turbine is usually fixed to shroud and casing by welding both ends. In such a vane structure, the damping in loading operation is comprised of the material damping and the aerodynamic damping, because the structural damping is very small. In this paper, first, the vane is modeled by the uniform beam fixed at both ends, and the effect of the material damping on the vane flutter is studied. In the stability analysis, the simple one-degree-of-freedom model is applied, where the linear aerodynamic model is used. In other words, it is assumed that the aerodynamic force due to the working fluid is proportional to the vane velocity and the negative damping coefficient does not change with amplitude. The allowable aerodynamic damping for the vane flutter is calculated and compared for the solid vane and the hollow vane. In addition, the vibration analysis of the actual steam turbine vane is carried out by 3D FEA (Finite Element Analysis), and the material damping of the solid and hollow vane is calculated by use of the results by FEA. The stability of the solid vane and the hollow vane on the flutter is also evaluated by use of the results calculated by FEA. From these results, the material damping characteristics of the steam turbine vane are clarified, as well as the effect of the material damping of the steam turbine vane on the flutter suppression.

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Numerical and Experimental Investigation of Axial Gap Variation in High-Pressure Steam Turbine Stages

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4035158 ◽

2017 ◽

Vol 139 (5) ◽

Cited By ~ 3

Author(s):

Juri Bellucci ◽

Filippo Rubechini ◽

Andrea Arnone ◽

Lorenzo Arcangeli ◽

Nicola Maceli ◽

...

Keyword(s):

High Pressure ◽

Steam Turbine ◽

Aerodynamic Performance ◽

Operating Conditions ◽

Performance Estimation ◽

Flow Angle ◽

High Pressure Steam ◽

Aspect Ratios ◽

Pressure Steam ◽

The Impact

This work aims at investigating the impact of axial gap variation on aerodynamic performance of a high-pressure steam turbine stage. Numerical and experimental campaigns were conducted on a 1.5-stage of a reaction steam turbine. This low speed test rig was designed and operated in different operating conditions. Two different configurations were studied in which blades axial gap was varied in a range from 40% to 95% of the blade axial chord. Numerical analyses were carried out by means of three-dimensional, viscous, unsteady simulations, adopting measured inlet/outlet boundary conditions. Two sets of measurements were performed: steady measurements, from one hand, for global performance estimation of the whole turbine, such as efficiency, mass flow, and stage work; steady and unsteady measurements, on the other hand, were performed downstream of rotor row, in order to characterize the flow structures in this region. The fidelity of computational setup was proven by comparing numerical results to measurements. Main performance curves and spanwise distributions have shown a good agreement in terms of both shape of curves/distributions and absolute values. Moreover, the comparison of two-dimensional maps downstream of rotor row has shown similar structures of the flow field. Finally, a comprehensive study of the axial gap effect on stage aerodynamic performance was carried out for four blade spacings (10%, 25%, 40%, and 95% of S1 axial chord) and five aspect ratios (1.0, 1.6, 3, 4, and 5). The results pointed out how unsteady interaction between blade rows affects stage operation, in terms of pressure and flow angle distributions, as well as of secondary flows development. The combined effect of these aspects in determining the stage efficiency is investigated and discussed in detail.

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The effect of hub leakage on the aerodynamic performance of high-pressure steam turbine stages

Journal of Mechanical Science and Technology ◽

10.1007/s12206-016-1247-6 ◽

2017 ◽

Vol 31 (1) ◽

pp. 445-454 ◽

Cited By ~ 3

Author(s):

Jeong Jin Lee ◽

Soo Young Kang ◽

Tong Seop Kim ◽

Seong Jin Park ◽

Gi Won Hong

Keyword(s):

High Pressure ◽

Steam Turbine ◽

Aerodynamic Performance ◽

High Pressure Steam ◽

Pressure Steam

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Aerodynamic Optimization Design of a Multistage Centrifugal Steam Turbine and Its Off-Design Performance Analysis

International Journal of Rotating Machinery ◽

10.1155/2017/4690590 ◽

2017 ◽

Vol 2017 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Hui Li ◽

Dian-Gui Huang

Keyword(s):

Steam Turbine ◽

Mass Flow ◽

Pressure Ratio ◽

Aerodynamic Performance ◽

Constant Speed ◽

Medium Size ◽

Aerodynamic Design ◽

One Dimensional ◽

Design Program ◽

The One

Centrifugal turbine which has less land occupation, simple structure, and high aerodynamic efficiency is suitable to be used as small to medium size steam turbines or waste heat recovery plant. In this paper, one-dimensional design of a multistage centrifugal steam turbine was performed by using in-house one-dimensional aerodynamic design program. In addition, three-dimensional numerical simulation was also performed in order to analyze design and off-design aerodynamic performance of the proposed centrifugal steam turbine. The results exhibit reasonable flow field and smooth streamline; the aerodynamic performance of the designed turbine meets our initial expectations. These results indicate that the one-dimensional aerodynamic design program is reliable and effective. The off-design aerodynamic performance of centrifugal steam turbine was analyzed, and the results show that the mass flow increases with the decrease of the pressure ratio at a constant speed, until the critical mass flow is reached. The efficiency curve with the pressure ratio has an optimum efficiency point. And the pressure ratio of the optimum efficiency agrees well with that of the one-dimensional design. The shaft power decreases as the pressure ratio increases at a constant speed. Overall, the centrifugal turbine has a wide range and good off-design aerodynamic performance.

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