The centrifugal compressor is the key component to improve the SCO2 cycle efficiency. In this paper, according to 150kW class supercritical carbon dioxide (SCO2) simple Brayton cycle, a centrifugal compressor with rotating speed 60000r/min is designed. For the small-scale SCO2 centrifugal compressor, the impeller tip clearance loss accounts for most of the aerodynamic loss. Therefore, the designed compressor performance is numerically studied by the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) and k-ε (Extended Wall Function) turbulence model. The large variations in physical properties for SCO2 near the critical make simulation be difficult to convergence. To keep the numerical stability and accuracy, 400 × 400 resolution physical properties tables are adopted by the physical properties tables verification. The designed SCO2 centrifugal compressor is with the isentropic efficiency of 73.2% and the pressure ratio of 2.207 under the design flow condition, and good off-design conditions performance are obtained. Compared to the flow condition without the impeller tip clearance, the isentropic efficiency of designed compressor decreases by 14%. For the impeller tip clearance leakage flow, the flow can be divided into three regions, the separation flow region which is along the mainstream flow direction, the back flow region which occupies the top of the impeller tip clearance and the downstream flow region which occupies the bottom of the impeller tip clearance. These flow phenomena and their causes are analyzed. The obtained results reveal that the designed centrifugal compressor meets the requirement of the aerodynamic performance for the 150kW class simple Brayton cycle. The detailed flow pattern of the designed SCO2 centrifugal compressor with consideration of the impeller tip leakage flow is also illustrated.
离心式压缩机是提高SCO2循环效率的关键部件。本文根据150kW级超临界二氧化碳(SCO2)简单布雷顿循环，设计了转速为60000r/min的离心压缩机。对于小型SCO2离心压气机，叶轮叶尖间隙损失占气动损失的大部分。因此，采用三维reynolds - average Navier-Stokes (RANS)和k-ε (Extended Wall Function)湍流模型对设计的压气机性能进行了数值研究。在临界附近，SCO2的物理性质变化很大，使得模拟难以收敛。为了保证数值的稳定性和准确性，物理性质表验证采用400 × 400分辨率的物理性质表。设计的SCO2离心压缩机在设计流量条件下等熵效率为73.2%，压比为2.207，在非设计工况下性能良好。与无叶顶间隙的流动状态相比，设计的压气机等熵效率降低了14%。对于叶轮叶尖间隙泄漏流动，可以将流动分为三个区域，即沿主流流动方向的分离流动区域，占据叶轮叶尖间隙顶部的回流区域和占据叶轮叶尖间隙底部的下游流动区域。分析了这些流动现象及其产生的原因。结果表明，所设计的离心压气机满足150kW级简单布雷顿循环的气动性能要求。文中还详细描述了考虑叶轮叶尖泄漏流的SCO2离心式压缩机的流动规律。
{"title":"Design and Aerodynamic Performance Investigations of Centrifugal Compressor for 150kW Class Supercritical Carbon Dioxide Simple Brayton Cycle","authors":"Run Cao, Zhigang Li, Qinghua Deng, Jun Li","doi":"10.1115/GT2020-16156","DOIUrl":"https://doi.org/10.1115/GT2020-16156","url":null,"abstract":"\u0000 The centrifugal compressor is the key component to improve the SCO2 cycle efficiency. In this paper, according to 150kW class supercritical carbon dioxide (SCO2) simple Brayton cycle, a centrifugal compressor with rotating speed 60000r/min is designed. For the small-scale SCO2 centrifugal compressor, the impeller tip clearance loss accounts for most of the aerodynamic loss. Therefore, the designed compressor performance is numerically studied by the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) and k-ε (Extended Wall Function) turbulence model. The large variations in physical properties for SCO2 near the critical make simulation be difficult to convergence. To keep the numerical stability and accuracy, 400 × 400 resolution physical properties tables are adopted by the physical properties tables verification. The designed SCO2 centrifugal compressor is with the isentropic efficiency of 73.2% and the pressure ratio of 2.207 under the design flow condition, and good off-design conditions performance are obtained. Compared to the flow condition without the impeller tip clearance, the isentropic efficiency of designed compressor decreases by 14%. For the impeller tip clearance leakage flow, the flow can be divided into three regions, the separation flow region which is along the mainstream flow direction, the back flow region which occupies the top of the impeller tip clearance and the downstream flow region which occupies the bottom of the impeller tip clearance. These flow phenomena and their causes are analyzed. The obtained results reveal that the designed centrifugal compressor meets the requirement of the aerodynamic performance for the 150kW class simple Brayton cycle. The detailed flow pattern of the designed SCO2 centrifugal compressor with consideration of the impeller tip leakage flow is also illustrated.","PeriodicalId":186943,"journal":{"name":"Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121265015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dynamic behavior of bladed disks in resonance crossing has been intensively investigated in the community of turbomachinery, addressing the attention to (1) the transienttype response that appear when the resonance is crossed with a finite sweep rate and (2) the localization of the vibration in the disk due to the blade mistuning. In real conditions, the two mentioned effects coexist and can interact in a complex manner. This paper investigates the problem by means of analytic solutions obtained through asymptotic expansions, as well as numerical simulations. The mechanical system is assumed as simple as possible: a 2-dof linear system defined through the three parameters: damping ratio ξ, frequency mistuning Δ, rotor acceleration Ω˙. The analytic solutions are calculated through the multiple-scale method.
{"title":"Identification of the Essential Features of the Transient Amplification of Mistuned Systems","authors":"L. Carassale, V. Denoël, C. Martel, L. P. Scheidt","doi":"10.1115/GT2020-15693","DOIUrl":"https://doi.org/10.1115/GT2020-15693","url":null,"abstract":"\u0000 The dynamic behavior of bladed disks in resonance crossing has been intensively investigated in the community of turbomachinery, addressing the attention to (1) the transienttype response that appear when the resonance is crossed with a finite sweep rate and (2) the localization of the vibration in the disk due to the blade mistuning. In real conditions, the two mentioned effects coexist and can interact in a complex manner. This paper investigates the problem by means of analytic solutions obtained through asymptotic expansions, as well as numerical simulations. The mechanical system is assumed as simple as possible: a 2-dof linear system defined through the three parameters: damping ratio ξ, frequency mistuning Δ, rotor acceleration Ω˙. The analytic solutions are calculated through the multiple-scale method.","PeriodicalId":186943,"journal":{"name":"Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2","volume":" 45","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132041957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Blahos, A. Vizzaccaro, L. Salles, Fadi El Haddad
Controlling vibration in jet engine remains one of the biggest challenges in aircraft engine design and conception. Methods dealing with vibration modelling usually rely on reduced order modelling techniques. This paper aims to provide a high fidelity method to solve vibration problems. It presents a parallel harmonic balance method applied to a full size problem. In order to be computationally efficient, a parallel harmonic balance method is used for the first time in solid mechanics. First, the parallel implementation of harmonic balance method is described in detail. The algorithm is designed to minimize communication between cores. Then, the software is tested for both beam and blade geometries. Finally, a scalability study shows promising acceleration when increasing the number of cores.
{"title":"Parallel Harmonic Balance Method for Analysis of Nonlinear Dynamical Systems","authors":"J. Blahos, A. Vizzaccaro, L. Salles, Fadi El Haddad","doi":"10.1115/GT2020-15392","DOIUrl":"https://doi.org/10.1115/GT2020-15392","url":null,"abstract":"\u0000 Controlling vibration in jet engine remains one of the biggest challenges in aircraft engine design and conception. Methods dealing with vibration modelling usually rely on reduced order modelling techniques. This paper aims to provide a high fidelity method to solve vibration problems. It presents a parallel harmonic balance method applied to a full size problem. In order to be computationally efficient, a parallel harmonic balance method is used for the first time in solid mechanics. First, the parallel implementation of harmonic balance method is described in detail. The algorithm is designed to minimize communication between cores. Then, the software is tested for both beam and blade geometries. Finally, a scalability study shows promising acceleration when increasing the number of cores.","PeriodicalId":186943,"journal":{"name":"Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114796439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High cycle fatigue in blades is triggered by oscillating forces. Devices such as shrouds, that exploit dry friction, are commonly introduced in the blade assembly to reduce the blade vibrations. If severe wear occurs, the effectiveness of the dry friction damping decreases, vibrations increase, and the number of cycles to failure of the blade diminishes. Mating surfaces in shrouds undergo high loads combined with relative displacement of low amplitude. This is the typical condition known as fretting. Coatings are commonly applied on damping surfaces of turbine blades to mitigate wear. This study investigates the wear mechanism of contact interfaces coated by Tribaloy® T-800, a coating greatly used in aeroengines. The experimental campaign was performed with a point contact test rig. The investigation was carried out using as test parameters temperature, normal load and fretting amplitude. Nine sets of parameters were analyzed at different test durations. Friction coefficients were computed using the hysteresis loops measured during the fretting tests. The worn surfaces were measured by an optical equipment based on focus variation and the volume losses were accurately measured. The wear region was observed by scanning electron microscopy at the end of each test. At room temperature, the friction coefficient was found substantially independent of the normal load. The wear rates at room temperature were higher than at high temperature. Observation of the worn surfaces by scanning electron microscopy revealed several brittle cracks. The damage mechanism changes from brittle (at room temperature) to ductile (at high temperature). The volume loss as a function of the dissipated energy was found independent of the normal load, showing that dissipated energy is a better variable rather than the number of wear cycles to show results of wear tests.
{"title":"Fretting Wear of T800 Coating in Aero-Engine Applications","authors":"M. Lavella, D. Botto","doi":"10.1115/GT2020-15608","DOIUrl":"https://doi.org/10.1115/GT2020-15608","url":null,"abstract":"\u0000 High cycle fatigue in blades is triggered by oscillating forces. Devices such as shrouds, that exploit dry friction, are commonly introduced in the blade assembly to reduce the blade vibrations. If severe wear occurs, the effectiveness of the dry friction damping decreases, vibrations increase, and the number of cycles to failure of the blade diminishes. Mating surfaces in shrouds undergo high loads combined with relative displacement of low amplitude. This is the typical condition known as fretting. Coatings are commonly applied on damping surfaces of turbine blades to mitigate wear.\u0000 This study investigates the wear mechanism of contact interfaces coated by Tribaloy® T-800, a coating greatly used in aeroengines. The experimental campaign was performed with a point contact test rig. The investigation was carried out using as test parameters temperature, normal load and fretting amplitude. Nine sets of parameters were analyzed at different test durations. Friction coefficients were computed using the hysteresis loops measured during the fretting tests. The worn surfaces were measured by an optical equipment based on focus variation and the volume losses were accurately measured. The wear region was observed by scanning electron microscopy at the end of each test.\u0000 At room temperature, the friction coefficient was found substantially independent of the normal load. The wear rates at room temperature were higher than at high temperature. Observation of the worn surfaces by scanning electron microscopy revealed several brittle cracks. The damage mechanism changes from brittle (at room temperature) to ductile (at high temperature). The volume loss as a function of the dissipated energy was found independent of the normal load, showing that dissipated energy is a better variable rather than the number of wear cycles to show results of wear tests.","PeriodicalId":186943,"journal":{"name":"Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130526359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper investigates the use of different model reduction methods accounting for geometric nonlinearities. These methods are adapted to retain physical degrees-of-freedom in the reduced space in order to ease contact treatment. These reduction methods are applied to a 3D finite element model of an industrial compressor blade (NASA rotor 37). In order to compare the different reduction methods, a scalar indicator is defined. This performance indicator allows to quantify the accuracy of the predicted displacement both locally (at the blade tip) and globally. The robustness of each method with respect to variations of the external excitation is also assessed. The performances of the reduction methods are then compared in the case of frictional contact between the blade tip and the surrounding casing. This work brings evidence that reduced order models provide a computationally efficient alternative to full order finite element models for the accurate prediction of the time response of structures with both distributed and localized nonlinearities.
{"title":"Comparative Study of Blades Reduced Order Models With Geometrical Nonlinearities and Contact Interfaces","authors":"E. Delhez, F. Nyssen, J. Golinval, Alain Batailly","doi":"10.1115/GT2020-14882","DOIUrl":"https://doi.org/10.1115/GT2020-14882","url":null,"abstract":"\u0000 This paper investigates the use of different model reduction methods accounting for geometric nonlinearities. These methods are adapted to retain physical degrees-of-freedom in the reduced space in order to ease contact treatment. These reduction methods are applied to a 3D finite element model of an industrial compressor blade (NASA rotor 37). In order to compare the different reduction methods, a scalar indicator is defined. This performance indicator allows to quantify the accuracy of the predicted displacement both locally (at the blade tip) and globally. The robustness of each method with respect to variations of the external excitation is also assessed. The performances of the reduction methods are then compared in the case of frictional contact between the blade tip and the surrounding casing. This work brings evidence that reduced order models provide a computationally efficient alternative to full order finite element models for the accurate prediction of the time response of structures with both distributed and localized nonlinearities.","PeriodicalId":186943,"journal":{"name":"Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2","volume":"11 24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120986304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Akshay Khadse, L. Vesely, J. Sherwood, Andres Curbelo, Vipul Goyal, N. Raju, J. Kapat, W. Kim
Supercritical CO2 (sCO2) can be utilized as a working fluid in various systems including high scale power cycle, portable power production unit, centralized cooling system and standalone cooling device. Lack of accurate predication tools such as heat transfer coefficient correlations and insufficient knowledge behind fundamental heat transfer processes can hinder its practical realization in key energy and cooling systems. The overall objective of the proposed study is to extend fundamental knowledge about heat transfer and fluid flow processes in conduits pertinent to sCO2 power cycle with an emphasis on buoyancy effects. Operational requirement of high pressures and temperatures for intended applications put a significant amount of constraints on measurement strategy and instrumentation. For this paper, experiments were conducted with uniform volumetric heat generation within pipe wall, for a single Reynolds number of 16,600 at test section inlet. The designed test apparatus and data reduction process are validated with high pressure air experiments, complemented by companion computations. Nusselt number was found to be within 10% of conventional correlations. For the test parameters and pipe size selected, factors of 2 to 4 variations in circumferential Nusselt number distributions are observed in sCO2 flow. Richardson number and other similar parameters to indicate importance of buoyancy-driven flow phenomena suggest that buoyancy forces caused by large density variation of sCO2 in flow cross-sections may cause the observed circumferential variations in Nusselt number.
{"title":"Study of Buoyancy Effects on Supercritical CO2 Heat Transfer in Circular Pipes","authors":"Akshay Khadse, L. Vesely, J. Sherwood, Andres Curbelo, Vipul Goyal, N. Raju, J. Kapat, W. Kim","doi":"10.1115/GT2020-15523","DOIUrl":"https://doi.org/10.1115/GT2020-15523","url":null,"abstract":"\u0000 Supercritical CO2 (sCO2) can be utilized as a working fluid in various systems including high scale power cycle, portable power production unit, centralized cooling system and standalone cooling device. Lack of accurate predication tools such as heat transfer coefficient correlations and insufficient knowledge behind fundamental heat transfer processes can hinder its practical realization in key energy and cooling systems. The overall objective of the proposed study is to extend fundamental knowledge about heat transfer and fluid flow processes in conduits pertinent to sCO2 power cycle with an emphasis on buoyancy effects. Operational requirement of high pressures and temperatures for intended applications put a significant amount of constraints on measurement strategy and instrumentation. For this paper, experiments were conducted with uniform volumetric heat generation within pipe wall, for a single Reynolds number of 16,600 at test section inlet. The designed test apparatus and data reduction process are validated with high pressure air experiments, complemented by companion computations. Nusselt number was found to be within 10% of conventional correlations.\u0000 For the test parameters and pipe size selected, factors of 2 to 4 variations in circumferential Nusselt number distributions are observed in sCO2 flow. Richardson number and other similar parameters to indicate importance of buoyancy-driven flow phenomena suggest that buoyancy forces caused by large density variation of sCO2 in flow cross-sections may cause the observed circumferential variations in Nusselt number.","PeriodicalId":186943,"journal":{"name":"Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115431078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dhinesh Thanganadar, F. Fornarelli, S. Camporeale, F. Asfand, K. Patchigolla
Supercritical carbon dioxide (sCO2) cycles are studied as the next-generation power cycles in order to reduce the cost of Concentrating Solar Power (CSP) plants. The design performance of numerous cycles has been investigated, nevertheless, the off-design and annual performance of these cycles are seldom studied. This plays a critical role in selecting an optimal cycle for CSP application, as an efficient power cycle influences the solar field size, consequently affecting the Levelised cost of electricity (LCOE). In this study, the design, off-design and annual performance of three sCO2 cycles; simple recuperative, recompression and partial-cooling cycles are studied. Multi-objective optimisation was performed and the off-design Pareto fronts were compared for the changes in the power cycle boundary conditions. Annual performance simulation was carried out, and the performance of the three cycles was compared when the power cycle is operated in maximum efficiency mode, which facilitates selecting the optimal cycle. The LCOE of the simple recuperated cycle was higher by roughly 1.7¢/kWh than recompression cycle when maximising the power cycle efficiency and the partial cooling cycle is higher by 0.2¢/kWh. However, operating the power cycle in the maximum efficiency mode significantly lowers the plant capacity factor (around 10–20%).
{"title":"Analysis of Design, Off-Design and Annual Performance of Supercritical CO2 Cycles for CSP Applications","authors":"Dhinesh Thanganadar, F. Fornarelli, S. Camporeale, F. Asfand, K. Patchigolla","doi":"10.1115/GT2020-14790","DOIUrl":"https://doi.org/10.1115/GT2020-14790","url":null,"abstract":"\u0000 Supercritical carbon dioxide (sCO2) cycles are studied as the next-generation power cycles in order to reduce the cost of Concentrating Solar Power (CSP) plants. The design performance of numerous cycles has been investigated, nevertheless, the off-design and annual performance of these cycles are seldom studied. This plays a critical role in selecting an optimal cycle for CSP application, as an efficient power cycle influences the solar field size, consequently affecting the Levelised cost of electricity (LCOE). In this study, the design, off-design and annual performance of three sCO2 cycles; simple recuperative, recompression and partial-cooling cycles are studied. Multi-objective optimisation was performed and the off-design Pareto fronts were compared for the changes in the power cycle boundary conditions. Annual performance simulation was carried out, and the performance of the three cycles was compared when the power cycle is operated in maximum efficiency mode, which facilitates selecting the optimal cycle. The LCOE of the simple recuperated cycle was higher by roughly 1.7¢/kWh than recompression cycle when maximising the power cycle efficiency and the partial cooling cycle is higher by 0.2¢/kWh. However, operating the power cycle in the maximum efficiency mode significantly lowers the plant capacity factor (around 10–20%).","PeriodicalId":186943,"journal":{"name":"Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121722403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the major sources of the damping of the forced vibration for bladed disk structures is the micro-slip motion at the contact interfaces of blade-disk joints. In this paper, the modeling strategies of nonlinear contact interactions at blade roots are examined using high-fidelity modelling of bladed disk assemblies and the nonlinear contact interactions at blade-disk contact patches. The analysis is performed in the frequency domain using multiharmonic harmonic balance method and analytically formulated node-to-node contact elements modelling frictional and gap nonlinear interactions. The effect of the number, location and distribution of nonlinear contact elements are analyzed using cyclically symmetric bladed disks. The possibility of using the number of the contact elements noticeably smaller than the total number of nodes in the finite element mesh created at the contact interface for the high-fidelity bladed disk model is demonstrated. The parameters for the modeling of the root damping are analysed for tuned and mistuned bladed disks. The geometric shapes of blade roots and corresponding slots in disks cannot be manufactured perfectly and there is inevitable root joint geometry variability within the manufacturing tolerances. Based on these tolerances, the extreme cases of the geometry variation are defined and the assessment of the possible effects of the root geometry variation on the nonlinear forced response are performed based on a set of these extreme cases.
{"title":"Blade Root Joint Modelling and Analysis of Effects of Their Geometry Variability on the Nonlinear Forced Response of Tuned and Mistuned Bladed Disks","authors":"Adam Koscso, E. Petrov","doi":"10.1115/GT2020-15225","DOIUrl":"https://doi.org/10.1115/GT2020-15225","url":null,"abstract":"\u0000 One of the major sources of the damping of the forced vibration for bladed disk structures is the micro-slip motion at the contact interfaces of blade-disk joints. In this paper, the modeling strategies of nonlinear contact interactions at blade roots are examined using high-fidelity modelling of bladed disk assemblies and the nonlinear contact interactions at blade-disk contact patches. The analysis is performed in the frequency domain using multiharmonic harmonic balance method and analytically formulated node-to-node contact elements modelling frictional and gap nonlinear interactions.\u0000 The effect of the number, location and distribution of nonlinear contact elements are analyzed using cyclically symmetric bladed disks. The possibility of using the number of the contact elements noticeably smaller than the total number of nodes in the finite element mesh created at the contact interface for the high-fidelity bladed disk model is demonstrated. The parameters for the modeling of the root damping are analysed for tuned and mistuned bladed disks.\u0000 The geometric shapes of blade roots and corresponding slots in disks cannot be manufactured perfectly and there is inevitable root joint geometry variability within the manufacturing tolerances. Based on these tolerances, the extreme cases of the geometry variation are defined and the assessment of the possible effects of the root geometry variation on the nonlinear forced response are performed based on a set of these extreme cases.","PeriodicalId":186943,"journal":{"name":"Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126982174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Joseph A. Beck, Jeffrey M. Brown, Daniel L. Gillaugh, Emily B. Carper, A. Kaszynski
Non-uniform manufacturing variations and uneven usage wear and damage, referred to as mistuning, can drastically alter the dynamic response of Integrally Blade Rotors (IBR)s. Optical scanners, combined with Finite Element Model (FEM) mesh metamorphosis algorithms, have provided capabilities to create analytical models that reduce the effect of geometrical uncertainties in numerical predictions. However, deviations in material properties cannot be obtained via optical scanning, so additional approaches are needed. A geometric mistuning Reduced-Order Model (ROM) is developed and modified to solve for unknown IBR sector eigenvalues that are linearly proportional to Elastic modulus. The developed approach accounts for both proportional and non-proportional mistuning and allows updating of the Elastic modulus for each sector in the ROM. Different tuned and mistuned modal reduction procedures are employed to understand the implications of each for identifying mistuning. Simulated test data with known inputs indicate the efficiency and accuracy of the method and improvements over using a traditional, tuned mode approach. The developed methods are then extended to bench-level traveling wave excitation data to discern how sector frequencies vary due to geometry and modulus mistuning.
{"title":"Integrally Bladed Rotor Mistuning Identification and Model Updating Using Geometric Mistuning Models","authors":"Joseph A. Beck, Jeffrey M. Brown, Daniel L. Gillaugh, Emily B. Carper, A. Kaszynski","doi":"10.1115/GT2020-15539","DOIUrl":"https://doi.org/10.1115/GT2020-15539","url":null,"abstract":"\u0000 Non-uniform manufacturing variations and uneven usage wear and damage, referred to as mistuning, can drastically alter the dynamic response of Integrally Blade Rotors (IBR)s. Optical scanners, combined with Finite Element Model (FEM) mesh metamorphosis algorithms, have provided capabilities to create analytical models that reduce the effect of geometrical uncertainties in numerical predictions. However, deviations in material properties cannot be obtained via optical scanning, so additional approaches are needed. A geometric mistuning Reduced-Order Model (ROM) is developed and modified to solve for unknown IBR sector eigenvalues that are linearly proportional to Elastic modulus. The developed approach accounts for both proportional and non-proportional mistuning and allows updating of the Elastic modulus for each sector in the ROM. Different tuned and mistuned modal reduction procedures are employed to understand the implications of each for identifying mistuning. Simulated test data with known inputs indicate the efficiency and accuracy of the method and improvements over using a traditional, tuned mode approach. The developed methods are then extended to bench-level traveling wave excitation data to discern how sector frequencies vary due to geometry and modulus mistuning.","PeriodicalId":186943,"journal":{"name":"Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132090040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Modal analysis of jet engine hardware is a necessary analytical tool utilized by engineers to understand and predict the vibrational risks to the system. Whereas blades and disks are critically analyzed due to their failure modes and effects, turbine vanes also need to be evaluated with respect to their design modal criteria to minimize potential risks to the engine. Although full hoop models of the entire system are most accurate, the time required for modeling and solution processing is typically prohibitive. Through cyclic symmetry and the use of commercial contact techniques, an analytical model may be created that provides the behavior of the entire system with a fraction of the computing time. However, methods for model simplification, including vane-only models, have not been addressed, and the potential for simplified models to accurately predict system modes is of particular interest. Accordingly, this paper studies the finite element modeling procedures for turbine vane modal analysis using multiple contact methods and cyclic symmetry applied to a turbine vane. An emphasis is placed on evaluating vane-only modeling techniques and an abbreviated turbine casing model. Additional comparisons with a traditional assembly model assess finite element model solution accuracy and efficiency. Ultimately, formal recommendations are offered for structural modeling of turbine vanes, including assessments of accuracy, reduction of frequency prediction capability, and computational efficiency gain.
{"title":"Consideration of Simplified Structural Models for Turbine Vane Modal Analysis","authors":"Natalie S. Korpics, Reid A. Berdanier","doi":"10.1115/GT2020-15806","DOIUrl":"https://doi.org/10.1115/GT2020-15806","url":null,"abstract":"\u0000 Modal analysis of jet engine hardware is a necessary analytical tool utilized by engineers to understand and predict the vibrational risks to the system. Whereas blades and disks are critically analyzed due to their failure modes and effects, turbine vanes also need to be evaluated with respect to their design modal criteria to minimize potential risks to the engine. Although full hoop models of the entire system are most accurate, the time required for modeling and solution processing is typically prohibitive. Through cyclic symmetry and the use of commercial contact techniques, an analytical model may be created that provides the behavior of the entire system with a fraction of the computing time. However, methods for model simplification, including vane-only models, have not been addressed, and the potential for simplified models to accurately predict system modes is of particular interest. Accordingly, this paper studies the finite element modeling procedures for turbine vane modal analysis using multiple contact methods and cyclic symmetry applied to a turbine vane. An emphasis is placed on evaluating vane-only modeling techniques and an abbreviated turbine casing model. Additional comparisons with a traditional assembly model assess finite element model solution accuracy and efficiency. Ultimately, formal recommendations are offered for structural modeling of turbine vanes, including assessments of accuracy, reduction of frequency prediction capability, and computational efficiency gain.","PeriodicalId":186943,"journal":{"name":"Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117197966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：