Experimental Analysis of Blade-Casing Contacts in a Centrifugal Compressor: Vibration and Thermal Aspects

Abstract Due to an increasing need for efficiency of turboengines, rotor--stator clearances are being lowered. Therefore, new designs show higher probability for contacts between rotors and casings. When contacts occur, high dynamic excitation levels as well as high temperatures due to dissipative mechanical phenomena may be expected. While numerical investigations have been proposed in the past, experiments are of high interest to fully understand the underlying phenomena behind rotor-stator contact interactions. In order to assess this situation, and based on former work performed by part of the authors, a rotor--stator contact rig has been used to investigate the mechanical and thermal behavior of a centrifugal low-pressure helicopter engine compressor. This rig operates under vacuum conditions to significantly reduce influence of the air surrounding the studied components. During the tests, multiple contact phases have been identified through increased vibration and temperature levels, as well as torque and rotational speed variations. A comprehensive analysis of the dynamic and thermal phenomena occurring during these experimental tests is proposed in this paper. Dynamic measurements are analyzed in the time and frequency domains, and nodal diameter contents are evaluated as well through full spectrum analyses. As a result, major influences from synchronous excitations in the frequency range of interest but also of higher modal families are highlighted. Post-trial observations indicate severe contact conditions leading to very high temperatures, abradable coating removal and material transfer between blade and casing.

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Experimental Analysis of Blade-Casing Contacts in a Centrifugal Compressor: Vibration and Thermal Aspects

Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2 ◽

10.1115/gt2020-15501 ◽

2020 ◽

Author(s):

Nicolas Guérin ◽

Claude Gibert ◽

Fabrice Thouverez ◽

Patricio Almeida

Keyword(s):

High Temperatures ◽

Rotational Speed ◽

Laser Doppler Vibrometer ◽

Experimental Tests ◽

Temperature Sensitive ◽

Material Transfer ◽

Full Spectrum ◽

Temperature Levels ◽

Post Trial ◽

Thermal Phenomena

Abstract Due to an increasing need for efficiency of turboengines, rotor–stator clearances are being lowered. Therefore, new designs show higher probability for contacts between rotors and casings. When contacts occur, high dynamic excitation levels as well as high temperatures due to dissipative mechanical phenomena may be expected. While numerical investigations have been proposed in the past, experiments are of high interest to fully understand the underlying phenomena behind rotor-stator contact interactions. In order to assess this situation, and based on former work performed by part of the authors, a rotor–stator contact rig has been used to investigate the mechanical and thermal behavior of a centrifugal low-pressure helicopter engine compressor. This rig operates under vacuum conditions to significantly reduce influence of the air surrounding the studied components. A near-zero gap condition is set at rest, then a rotational speed sweep allows to target the specific operating range of interest. Both structures are fitted with strain gauges, and a torquemeter is installed on the shaft to measure resistive phenomena on the bladed disk. A scanning laser Doppler vibrometer is aimed at the casing through a window to provide additional displacement measurements. Temperatures are measured by an array of thermocouples equally spaced around the casing, close to the expected contact area. Also, using temperature-sensitive markings, overall temperature mappings on the impeller are performed. During the tests, multiple contact phases have been identified through increased vibration and temperature levels, as well as torque and rotational speed variations. A comprehensive analysis of the dynamic and thermal phenomena occurring during these experimental tests is proposed in this paper. Dynamic measurements are analyzed in the time and frequency domains, and nodal diameter contents are evaluated as well through full spectrum analyses. As a result, major influences from synchronous excitations in the frequency range of interest but also of higher modal families are highlighted. Post-trial observations indicate severe contact conditions leading to very high temperatures, abradable coating removal and material transfer between blade and casing.

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Material transfer through the interface between peraluminous metapelite and gedrite-bearing gneiss at high temperatures and moderate pressures

Geochemistry International ◽

10.1134/s0016702914110032 ◽

2014 ◽

Vol 53 (1) ◽

pp. 39-59 ◽

Cited By ~ 1

Author(s):

G. G. Lepezin

Keyword(s):

High Temperatures ◽

Material Transfer

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Material transfer behaviour between a Ti6Al4V blade and an aluminium hexagonal boron nitride abradable coating during high-speed rubbing

Wear ◽

10.1016/j.wear.2014.10.001 ◽

2015 ◽

Vol 322-323 ◽

pp. 76-90 ◽

Cited By ~ 22

Author(s):

W.H. Xue ◽

S.Y. Gao ◽

D.L. Duan ◽

Y. Liu ◽

S. Li

Keyword(s):

Boron Nitride ◽

High Speed ◽

Hexagonal Boron Nitride ◽

Material Transfer ◽

Abradable Coating

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Analysis of the Partial Demagnetization Process of Magnets in a Line Start Permanent Magnet Synchronous Motor

Energies ◽

10.3390/en13215562 ◽

2020 ◽

Vol 13 (21) ◽

pp. 5562

Author(s):

Mariusz Baranski ◽

Wojciech Szelag ◽

Wieslaw Lyskawinski

Keyword(s):

Permanent Magnet ◽

Permanent Magnet Synchronous Motor ◽

Experimental Studies ◽

Experimental Tests ◽

Synchronous Motor ◽

Effect Of Temperature ◽

Start Up ◽

Calculation Results ◽

Thermal Phenomena ◽

The Impact

The paper justifies the validity of analyzing the impact of temperature and the process of partial demagnetization of magnets on the operating parameters of machines. To analyze this impact, a field model of coupled electromagnetic and thermal phenomena in a permanent magnet synchronous motor was proposed. The non-linearity of the magnetic circuit, the effect of temperature on the magnetic, electrical and thermal properties of the materials as well as the developed method of modeling the process of partial demagnetization of the magnet were taken into account. Based on this model, an algorithm and software were developed to analyze the effect of temperature and the process of partial demagnetization of magnets on the work of the line start permanent magnet synchronous motor (LSPMSM). The elaborated software was used to study the effect of temperature during the motor starting phase on the magnetization state of the magnets after the start-up process. The calculation results were compared to the results of experimental studies. The experimental tests were carried out on a specially constructed test stand. The results of the research on the process of partial demagnetization of the magnets are presented and the conclusions resulting therefrom formulated.

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Modeling of Abradable Coating Removal in Aircraft Engines Through Delay Differential Equations

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4024959 ◽

2013 ◽

Vol 135 (10) ◽

Cited By ~ 17

Author(s):

Nicolas Salvat ◽

Alain Batailly ◽

Mathias Legrand

Keyword(s):

Differential Equations ◽

Delay Differential Equations ◽

Computational Cost ◽

Mathematical Framework ◽

Machining Processes ◽

Abradable Coating ◽

Excited Vibration ◽

Time Marching ◽

Coating Removal ◽

Delay Differential

In modern turbomachinery, abradable materials are implemented on casings to reduce operating tip clearances and mitigate direct unilateral contact occurrences between rotating and stationary components. However, both experimental and numerical investigations revealed that blade/abradable interactions may lead to blade failures. In order to comprehend the underlying mechanism, an accurate modeling of the abradable removal process is required. Time-marching strategies where the abradable removal is modeled through plasticity are available but another angle of attack is proposed in this work. It is assumed that the removal of abradable liners shares similarities with machine tool chatter encountered in manufacturing. Chatter is a self-excited vibration caused by the interaction between the machine and the workpiece through the cutting forces and the corresponding dynamics are efficiently captured by delay differential equations. These equations differ from ordinary differential equations in the sense that previous states of the system are involved in the formulation. This mathematical framework is employed here for the exploration of the blade stability during abradable removal. The proposed tool advantageously features a reduced computational cost and consistency with existing time-marching solution methods. Potentially dangerous interaction regimes are accurately predicted and instability lobes match both the flexural and torsional modal responses. Essentially, the regenerative nature of chatter in machining processes can also be attributed to abradable coating removal in turbomachinery.

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Demonstration of Thermophotovoltaics for a Full-Spectrum Solar Energy System

Solar Energy ◽

10.1115/isec2004-65125 ◽

2004 ◽

Author(s):

Dan Dye ◽

Byard Wood ◽

Lewis Fraas ◽

Jeanette Kretschmer

Keyword(s):

Solar Energy ◽

Visible Light ◽

Gallium Antimonide ◽

Solar Spectrum ◽

Experimental Tests ◽

Energy System ◽

Collection System ◽

Full Spectrum ◽

Experimental Apparatus ◽

Array Performance

A non-imaging (NI) device and thermophotovoltaic (TPV) array for use in a full-spectrum solar energy system has been designed, built, and tested [1,2,3]. This system was designed to utilize the otherwise wasted infrared (IR) energy that is separated from the visible portion of the solar spectrum before the visible light is harvested. The IR energy will be converted to electricity via a gallium antimonide (GaSb) TPV array. The experimental apparatus for the testing of the IR optics and TPV performance is described. Array performance data will be presented, along with a comparison between outdoor experimental tests and laboratory flash tests. An analysis of the flow of the infrared energy through the collection system will be presented, and recommendations will be made for improvements. The TPV array generated a maximum of 26.7 W, demonstrating a conversion efficiency of the IR energy of 12%.

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APPLICABILITY OF CARBON FIBRES IN REFRACTORY CEMENT COMPOSITES

Acta Polytechnica ◽

10.14311/ap.2018.58.0346 ◽

2018 ◽

Vol 58 (6) ◽

pp. 346-354

Author(s):

Ondřej Holčapek ◽

Pavel Reiterman ◽

Petr Konvalinka

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

High Temperatures ◽

Elevated Temperatures ◽

Ceramic Powder ◽

Cement Composite ◽

Industrial Applications ◽

Carbon Fibres ◽

Refractory Cement ◽

Temperature Levels

The main objective of this article is to present the influence of high temperatures on mechanical properties of advanced refractory cement composite reinforced with carbon fibres. The presented material is suitable for industrial applications and can withstand elevated temperatures up to 1000 °C. The action of high temperatures was investigated on two temperature levels 600 °C and 1000 °C and was compared to reference specimens dried at 105 °C. The carbon fibres with flexural strength of 4100MPa were applied in dosage 0.50 %, 0.75% and 1.00% of the total volume. The second investigated modification was mutual ratio between aluminous cement and fine ceramic powder. The influence of high temperatures was investigated by measuring the bulk density, compressive and flexural strength, dynamic modulus of elasticity and fracture energy; all measured on prismatic specimens 40 × 40 × 160 mm. The workability of fresh mixture was limited by the maximum dosage of carbon fibres in 1% of the total volume. Based on the workability and evaluation of residual mechanical properties after temperature loading, the best was found to be the combination of carbon fibres in dosage of 0.75% by volume.

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Abradable Coating Removal in Turbomachines: A Macroscopic Approach Accounting for Several Wear Mechanisms

Volume 7B: Structures and Dynamics ◽

10.1115/gt2015-42500 ◽

2015 ◽

Cited By ~ 1

Author(s):

Bérenger Berthoul ◽

Alain Batailly ◽

Mathias Legrand ◽

Laurent Stainier ◽

Patrice Cartraud

Keyword(s):

Wear Mechanisms ◽

Structural Integrity ◽

Aircraft Engine ◽

Contact Forces ◽

Macroscopic Model ◽

3D Interaction ◽

Abradable Coating ◽

Blade Tip ◽

Coating Removal ◽

Physical Phenomena

Abradable materials are widely used as a coating within compressor and turbine stages of modern aircraft engines in order to reduce operating blade-tip/casing clearances and thus maximize the engine energy efficiency. However, recent investigations revealed that the interaction between a blade and these materials may threaten blades structural integrity. Consequently, there is a need for a better understanding of the physical phenomena at play and for an accurate modelling of the interaction in order to predict hazardous events. The cornerstone of related numerical investigations lies in the modelling of the abradable coating removal due to the blade/abradable coating interaction and the associated contact forces along the contact interface. In this context, this article presents a macroscopic model for abradable coating removal accounting for key wear mechanisms including adhesive wear, abrasive wear, micro-rupture wear and machining wear. It is coupled with an in-house numerical strategy for the modelling of full 3D blade/abradable coating interactions within turbomachines and applied to an aircraft engine. Numerical results are compared with respect to existing models and available experimental data. The applicability of the proposed model for 3D interaction simulations is underlined as well as the consistency of the obtained results with experimental observations.

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Evaluation of the fire resistance of steel-reinforced concretefilled steel tubular columns with a circular cross-section

Journal of Physics Conference Series ◽

10.1088/1742-6596/2153/1/012005 ◽

2022 ◽

Vol 2153 (1) ◽

pp. 012005

Author(s):

J P Rojas Suárez ◽

J A Pabón León ◽

M S Orjuela Abril

Keyword(s):

Numerical Simulation ◽

Reinforced Concrete ◽

Cross Sections ◽

Fire Resistance ◽

Circular Cross Section ◽

Experimental Tests ◽

Steel Reinforced Concrete ◽

Tubular Columns ◽

Temperature Levels ◽

Physical Phenomena

Abstract In the present investigation, an analysis of the fire resistance of the steel-reinforced concrete-filled steel tubular columns with circular cross-sections was carried out by means of numerical simulation. The development of the study was carried out by means of numerical simulation to predict the behavior of the column against fire. The results of the numerical model are validated by comparing the temperature levels obtained through experimental tests. From the results obtained, it is shown that the increase in the contact area between the steel and the concrete reduces the average temperature of the column, which implies a greater resistance to fire. The fire resistance of the columns with the steel profile designs are between 3.4 - 3.6 times higher compared to the column only made of concrete, which is an indication of the excellent performance of the steel-reinforced concrete-filled steel tubular columns with circular cross- sections columns. In general, the methodology proposed in this research allows the analysis of the thermal physical phenomena of the different columns used for the construction of buildings.

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