Experimental Investigation of the Grouped Blade Vibration for Steam Turbine by Noncontact Sensors

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Tomomi Nakajima ◽  
Kiyoshi Segawa ◽  
Hiromichi Kitahara ◽  
Akimitsu Seo ◽  
Yutaka Yamashita ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Steam Turbine ◽  
Maximum Amplitude ◽  
Amplitude Distribution ◽  
Maximum Response ◽  
Blade Vibration ◽  
Air Jet ◽  
Measurement Results ◽  
Calculation Results ◽  
Noncontact Sensors

All turbine blades have mistuned structures caused by manufacturing variations within the manufacturing tolerance, such as the geometrical deviations and variance of material properties. The mistuning effect has a known tendency to increase the dynamic stress, but it is also known to be difficult to predict the maximum vibration response before the operation. This paper studies the blade vibration of grouped blades in a low-pressure steam turbine. The study objectives are to characterize the vibration behavior of the grouped blade structure and to evaluate the maximum response of all blades in a stage experimentally. An experimental investigation is carried out in a vacuum chamber, and blades are excited by an air jet during start-up and shut-down. The circumferential blade amplitude distribution is measured by noncontact sensors (NCSs) and strain gauges (SGs). The circumferential blade amplitude distribution is found to differ depending on vibration modes and nodal diameters (NDs), but the relative tendency is almost the same for all types of operation at each mode and all NDs. Therefore, the median of all experimental results obtained with the NCSs is used in a comparison with calculation results and results of two theoretical curves obtained using equations from the literature. In comparing the measurement results and the calculation results, the circumferential blade amplitude distribution is not the same with all modes and NDs. However, the maximum amplitude magnification is about 1.5–1.8, and all measurement results are lower than the results for the two theoretical equations. This means the maximum response comparison to the tuned blade gives an evaluation on the safe side by the two theoretical equations.

Experimental Investigation of the Grouped Blade Vibration for Steam Turbine by Non-Contact Sensors

2017 ◽  
Author(s):  
Tomomi Nakajima ◽  
Kiyoshi Segawa ◽  
Hiromichi Kitahara ◽  
Akimitsu Seo ◽  
Yutaka Yamashita ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Steam Turbine ◽  
Maximum Amplitude ◽  
Amplitude Distribution ◽  
Maximum Response ◽  
Blade Vibration ◽  
Air Jet ◽  
Measurement Results ◽  
Calculation Results ◽  
Contact Sensors

All turbine blades have mistuned structures caused by manufacturing variations within the manufacturing tolerance, such as the geometrical deviations and variance of material properties. The mistuning effect has a known tendency to increase the dynamic stress, but it is also known to be difficult to predict the maximum vibration response before the operation. This paper studies the blade vibration of grouped blades in a low-pressure steam turbine. The study objectives are to characterize the vibration behavior of the grouped blade structure and to evaluate the maximum response of all blades in a stage by experiments. An experimental investigation is carried out in a vacuum chamber, and blades are excited by an air jet during start-up and shut-down. The circumferential blade amplitude distribution is measured by non-contact sensors and strain gauges. The circumferential blade amplitude distribution is found to differ depending on vibration modes and nodal diameters, but the relative tendency is almost the same for all types of operation at each mode and all nodal diameters. Therefore, the median of all experimental results obtained with the non-contact sensors are used in a comparison with calculation results and two theoretical curves obtained using equations from the literature. In comparing the measurement results and the calculation results, the circumferential blade amplitude distribution is not the same with all modes and nodal diameters. However, the maximum amplitude magnification is about 1.5–1.8, and all measurement results are lower than the results for the two theoretical equations. This means the maximum response compared to the tuned blade can be evaluated on the safe side by the two theoretical equations.

Investigations on Maximum Amplitude Amplification Factor of Real Mistuned Bladed Structures

2012 ◽  
Author(s):  
David Hemberger ◽  
Dietmar Filsinger ◽  
Hans-Jörg Bauer
Keyword(s):  
Amplification Factor ◽  
Maximum Amplitude ◽  
Experimental Results ◽  
Blade Vibration ◽  
Turbine Wheel ◽  
Local Variance ◽  
Measurement Results ◽  
Theoretical Investigations ◽  
Maximum Amplification ◽  
Amplitude Amplification

The production of bladed structures, e.g. turbine and compressor wheels, is a subject of statistical scatter. The blades are designed to be identical but differ due to small manufacturing tolerances. This can be local variance of material properties and geometrical deviations, which is indicated as mistuning of the structure. This article deals with the amplitude amplification factor of bladed structures caused by mistuning of real geometries. Theoretical investigations and also experimental results show, that mistuning of the structure leads to an amplification of blade vibration amplitudes and hence to increased stresses in blades. The existing theoretical considerations by Whitehead from 1966 and Kenyon & Griffin from 2001 are compared with results of blade vibration measurements. For that purpose, measurement results of turbine and compressor wheels from publication in recent years were analyzed. These experimental results stem from measurements with strain gauges as well as tip timing measurements to determine blade vibration amplitudes. In addition to this extended literature survey, the authors also examined results from in-house tip timing measurements of a radial turbine wheel from a vehicular turbocharger. The maximum amplification factor (MAF) and the degree of localization were evaluated. The comparison with the theory by Kenyon & Griffith revealed that the estimated maximum amplification factor was always higher than the values from the analyzed data. The measured MAF were besides one exception of a highly localized vibration form, which does not meet the theory’s assumptions, between 54% and 99.5% of the expected value. In this sense the theory has been proven.

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.

Research of Calculation Models for Exhaust Enthalpy of Steam Turbine

2012 ◽  
Vol 550-553 ◽  
pp. 3160-3163
Author(s):  
Yong Guang Ma ◽  
Ning Ran ◽  
Bing Zheng
Keyword(s):  
Energy Balance ◽  
Steam Turbine ◽  
Open System ◽  
Performance Monitoring ◽  
Thermal Power ◽  
Energy Balance Equation ◽  
Calculation Model ◽  
Power Generating Unit ◽  
Calculation Results ◽  
Unit Performance

For the low pressure (LP) cylinder of a steam turbine, computation of the exhaust enthalpy is an important part in thermal power generating unit performance monitoring. A new online model for calculating the exhaust enthalpy was proposed aiming at the limitation of existing online calculation model for calculating the enthalpy of steam turbine LP cylinder exhaust steam. This model treats LP cylinder, condenser and corresponding heater as an open system, according to the energy balance equation of this open system, figuring out its exhaust enthalpy. Calculation results of typical steam turbine show that: in a large load change range, the results are close to thermal experimental value, the accuracy is similar to energy balance method.

Theory and Application of Stage-by-Stage Evaluation for Steam Turbine State-Line

1984 ◽  
Vol 28 (04) ◽  
pp. 240-260
Author(s):  
Robert Latorre ◽  
Zisimos Mourelatos ◽  
Efstratios Nikolaidis
Keyword(s):  
Theoretical Model ◽  
Computer Program ◽  
Steam Turbine ◽  
Heat Balance ◽  
Standard Heat ◽  
Balance Calculation ◽  
Calculation Results ◽  
Design Case ◽  
The Heat Balance

A theoretical model of a steam turbine is formulated based on idealized Curtis and reaction stages to obtain expressions for a stage-by-stage evaluation of the turbine state line. Using typical stage geometries and corrections a computer program was developed to size the turbine and evaluate its state line at design conditions. A comparison of the heat balance made with the stage-by-stage state line and the standard heat balance is presented. For the design case of 30 000 shp it is shown that the differences in the heat balance calculation results are within ±0.5 percent.

scholarly journals Condensation of Novec 649 refrigerant in pipe minichannels

2018 ◽  
Vol 70 ◽  
pp. 02002 ◽  
Author(s):  
Tadeusz Bohdal ◽  
Henryk Charun ◽  
Małgorzata Sikora
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Mass Flux ◽  
Flow Structures ◽  
Test Results ◽  
Calculation Results ◽  
Vapour Quality ◽  
Inner Diameter

The paper presents the results of experimental investigation of Novec 649 refrigerant condensation in tube minichannels. This is a low-pressure refrigerant. This investigations are basis for flow structures visualization during condensation in pipe minichannels. The local and the average values of pressure drop (Δp/L) and heat transfer coefficient α in the whole range of the changes of vapour quality (x = 1 ÷ 0) were calculated. On the basis of the obtained test results there was illustrated the influence of the vapour quality x, the mass flux density G and the inner diameter of channel d changes on the studied parameters. These results were compared with the calculation results based on the dependencies of other authors.

scholarly journals Process-Induced Distortions Characterization of MBWK Fabric Reinforced Composite Helmet Shell

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2983
Author(s):  
He Xiang ◽  
Yaming Jiang ◽  
Yexiong Qi ◽  
Jialu Li
Keyword(s):  
Thin Shell ◽  
High Performance ◽  
Laser Scanning ◽  
Textile Composites ◽  
Reinforced Composite ◽  
Measurement Results ◽  
Calculation Results ◽  
High Performance Composite ◽  
Working Procedure

In order to characterize the process-induced distortions of 3D thin shell composites with complex shape, the multilayered biaxial weft knitted (MBWK) fabric reinforced high-performance composite helmet was selected as the research object, and the 3D laser scanning machine was used to scan the helmet surface, then the 3D scanning data was compared with the CAD model to evaluate the deformation. The results and discussion indicated that the conventional method was workable, but the speed of convergence was slow and the calculation results were easy to drop into local optimization. According to detailed analysis, a measurement method focusing on the principle of “Feature Distance” was developed. The measurement results shown that this method can not only give accurate results, but also reduce working procedure and greatly save the computing resources, which is proved to be a feasible approach for the deformation measurement foundation of 3D thin shell textile composites.

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