TY - CHAP A1 - Beirow, Bernd A1 - Kühhorn, Arnold A1 - Figaschewsky, Felix A1 - Hönisch, Peter A1 - Giersch, Thomas A1 - Schrape, Sven T1 - Model Update and Validation of a Mistuned High Pressure Compressor Blisk T2 - Proceedings of ISABE 2017, ISABE-2017-22568, Manchester, September 3.-8., 2017 Y1 - 2017 UR - https://isabe2017.org/ PB - ISABE ER - TY - CHAP A1 - Kober, Markus A1 - Kühhorn, Arnold A1 - Keskin, Akin A1 - Singh, Kai Navtej T1 - Challenges and opportunities of thermomechanical FEM simulations of high fidelity aero-engine models by implicit time-integration T2 - Proceedings of ISABE 2017, ISABE-2017-22568, Manchester, September 3.-8., 2017 Y1 - 2017 UR - https://isabe2017.org/ PB - ISABE ER - TY - CHAP A1 - Figaschewsky, Felix A1 - Kühhorn, Arnold A1 - Giersch, Thomas T1 - A Finite Element Based Least Square Fit for the Assessment of Integral and Non-Integral Vibrations With Blade Tip Timing T2 - Proceedings of ISROMAC 2017, Maui, Hawaii, December 16-21, 2017 N2 - This paper aims at improving the robustness and accuracy of the least square fit technique utilized in blade tip timing (BTT) measurements of blade vibrations by proposing two modifications. The first proposal is to replace the lines of the original least square problem by differences of consecutive lines. Thereby, the static deflection as well as the circumferential blade positioning error cancels out and the robustness is improved by removing these uncertainties inherently. The second proposal is to replace the fit of piecewise constant vibration amplitudes within the chosen block length by a linear or cubic spline in the frequency (integral) or time (non-integral) regime. This does not only suppress overshoots due to distorted acceleration or deceleration manoeuvres but also allows for a ”coarser analysis grid” (i.e. larger block length) without loosing amplitude accuracy. Thereby it smooths out random errors more efficiently and increases the orthogonality of the relevant EO or vibration frequency to unwanted signal components. KW - Blade Tip Timing KW - Non-Intrusive Measurements KW - Blade Vibration Y1 - 2017 UR - http://isromac-isimet.univ-lille1.fr/index.php?rubrique=abstract17_&num=2 ER - TY - CHAP A1 - Hanschke, Benjamin A1 - Kühhorn, Arnold A1 - Schrape, Sven A1 - Giersch, Thomas T1 - Consequences of Borescope Blending Repairs on Modern HPC Blisk Aeroelasticity T2 - Proceedings of ISROMAC 2017, Maui, Hawaii, December 16-21, 2017 N2 - Objective of this paper is to analyse the consequences of borescope blending repairs on the aeroelastic behaviour of a modern HPC blisk. To investigate the blending consequences in terms of aerodynamic damping and forcing changes, an exemplary blending of a rotor blade is modelled. Steady state flow parameters like total pressure ratio, polytropic efficiency and the loss coefficient are compared. Furthermore, aerodynamic damping is computed utilising the AIC approach for both geometries. Results are confirmed by SPF simulations for specific nodal diameters of interest. Finally, an unidirectional forced response analysis for the nominal and the blended rotor is conducted to determine the aerodynamic force exciting the blade motion. Fourier transformation of the forcing signal yields to the frequency content as well as the forcing amplitudes. As a result of the present analysis, the amplification of expected blade vibration amplitude is computed. KW - Aeroelasticity KW - Compressor Blisk KW - Blending Repair KW - Forced Response KW - Arodynamic Damping Y1 - 2017 UR - http://isromac-isimet.univ-lille1.fr/index.php?rubrique=abstract17_&num=2 ER - TY - CHAP A1 - Beirow, Bernd A1 - Figaschewsky, Felix A1 - Kühhorn, Arnold A1 - Bornholm, Alfons T1 - Vibration Analysis of an Axial Turbine Blisk with Optimized Intentional Mistuning Pattern T2 - Proceedings of ISROMAC 2017, Maui, Hawaii, December 16-21, 2017 N2 - Aiming to limit the forced response of an axial turbine blisk for ship Diesel engine applications efforts have been made to increase the aerodynamic damping contribution for the most critical modes. In this regard the potential of intentional mistuning is investigated since it offers the opportunity to ensure a safe operation without a severe loss of aerodynamic performance. Genetic algorithms have been chosen to derive an optimized mistuning pattern. In order to keep the manufacturing effort within a limit only two possible blade geometries are allowed which means that an integer optimization problem has been formulated. For the purpose of demonstrating the benefit of the intentional mistuning pattern found, two blisk prototypes have been manufactured: One with and another one without employing intentional mistuning for purposes of comparison. Furthermore, this offers the opportunity for an experimental determination of mistuning being really manufactured and other modal properties as well. The experimental data basis is employed to update structural models which are well suited to demonstrate the forced response reduction under operational conditions. KW - Blisk KW - Intentional Mistuning KW - Low Engine Order Excitation Y1 - 2017 UR - http://isromac-isimet.univ-lille1.fr/index.php?rubrique=abstract17_&num=21 ER - TY - GEN A1 - Beirow, Bernd A1 - Figaschewsky, Felix A1 - Kühhorn, Arnold A1 - Bornholm, Alfons T1 - Modal Analyses of an Axial Turbine Blisk With Intentional Mistuning T2 - Journal of Engineering for Gas Turbines and Power N2 - The potential of intentional mistuning to reduce the maximum forced response is analyzed within the development of an axial turbine blisk for ship diesel engine turbocharger applications. The basic idea of the approach is to provide an increased aerodynamic damping level for particular engine order excitations and mode shapes without any significant distortions of the aerodynamic performance. The mistuning pattern intended to yield a mitigation of the forced response is derived from an optimization study applying genetic algorithms. Two blisk prototypes have been manufactured a first one with and another one without employing intentional mistuning. Hence, the differences regarding the real mistuning and other modal properties can be experimentally determined and evaluated as well. In addition, the experimental data basis allows for updating structural models which are well suited to compute the forced response under operational conditions. In this way, the real benefit achieved with the application of intentional mistuning is demonstrated. KW - Modal Analyses KW - Turbines Y1 - 2018 UR - http://gasturbinespower.asmedigitalcollection.asme.org/article.aspx?articleid=2649209#Abstract U6 - https://doi.org/10.1115/1.4037588 SN - 0742-4795 SN - 1528-8919 VL - 140 IS - 1 SP - 012503-1 EP - 012503-11 ER - TY - GEN A1 - Kober, Markus A1 - Kühhorn, Arnold T1 - Stable implicit time-integration of flexible rotating structures—explanation for instabilities and concepts for avoidance T2 - Applied Mathematical Modelling N2 - Instabilities occurring during the implicit time-integration are still handicapping a time-efficient solution of large FEM systems of equations. Especially the simulation of flexible rotating structures is barely mastered by implicit FEM codes. For this, the Newmark algorithm and related algorithms are used for many years. Here, we derive the reasons for the mentioned inevitable numerical issues and present concepts that lead to an efficient and stable solution. KW - Nonlinear implicit time-integration KW - Instability KW - Newmark KW - Rotating structures Y1 - 2018 U6 - https://doi.org/10.1016/j.apm.2018.03.017 SN - 0307-904X VL - 60 SP - 235 EP - 243 ER - TY - GEN A1 - Beirow, Bernd A1 - Kühhorn, Arnold A1 - Figaschewsky, Felix A1 - Bornholm, Alfons A1 - Repetckii, Oleg V. T1 - Forced Response Reduction of a Blisk by Means of Intentional Mistuning T2 - Journal of Engineering for Gas Turbines and Power N2 - The effect of intentional mistuning has been analyzed for an axial turbocharger blisk with the objective of limiting the forced response due to low engine order excitation (LEO). The idea behind the approach was to increase the aerodynamic damping for the most critical fundamental mode in a way that a safe operation is ensured without severely losing aerodynamic performance. Apart from alternate mistuning a more effective mistuning pattern is investigated, which has been derived by means of optimization employing genetic algorithms. In order to keep the manufacturing effort as small as possible only two blade different geometries have been allowed which means that an integer optimization problem has been formulated. Two blisk prototypes have been manufactured for the purpose of demonstrating the benefit of the intentional mistuning pattern identified in this way: A first one with and a second one without employing intentional mistuning. The real mistuning of the prototypes has been experimentally identified. It is shown that the benefit regarding the forced response reduction is retained in spite of the negative impact of unavoidable additional mistuning due to the manufacturing process. Independently, further analyzes have been focused on the robustness of the solution by considering increasing random structural mistuning and aerodynamic mistuning as well. The latter one has been modeled by means of varying aerodynamic influence coefficients (AIC) as part of Monte Carlo simulations. Reduced order models have been employed for these purposes. Y1 - 2019 UR - http://gasturbinespower.asmedigitalcollection.asme.org/article.aspx?articleid=2687503 U6 - https://doi.org/10.1115/1.4040715 SN - 1528-8919 SN - 0742-4795 VL - 141 IS - 1 SP - 011008-1 EP - 011008-8 ER - TY - CHAP A1 - Kober, Markus A1 - Kühhorn, Arnold A1 - Keskin, Akin T1 - Optimization of Newmark-Euler Time-Integration Parameters for a Stable and Efficient Implicit Simulation of Rotating Elastic Structures T2 - Proceedings of 15th German LS-DYNA Forum Y1 - 2018 SN - 978-3-9816215-5-6 SP - 235 EP - 238 PB - DYNAmore GmbH CY - Stuttgart ER - TY - GEN A1 - Weber, Robby A1 - Kühhorn, Arnold A1 - Heinrich, Christoph Rocky T1 - Modelling and analysis of a high-speed turbine impeller concerning mistuning T2 - The 14th International Conference of machinery (VETOMAC XIV), Lissabon, 10-13 September 2018 N2 - As-manufactured impellers behave significantly different from nominal impellers. There are no identical blades due to geometric and material deviations. In this paper three model updating procedures are discussed with the objective to achieve realistic models of as-manufactured impellers. The techniques are applied to radial inflow turbine wheel of an exhaust gas turbocharger. The first approach creates a model through optical measurement and mesh morphing. The second approach is based on a contactless measurement of blade individual vibration responses. An iterative update process gains the corresponding mistuning pattern and thus the associated model. Third, a model is found by an optimisation, that identified a mistuning pattern, that fits modal characteristics, which are evaluated during experimental modal analysis at vacuum. In-depth analyses of these models are realised to determine advantages and drawbacks of the procedures. Y1 - 2018 U6 - https://doi.org/10.1051/matecconf/201821118002 ER - TY - CHAP A1 - Figaschewsky, Felix A1 - Kühhorn, Arnold T1 - An Inverse Approach to Identify Tuned Aerodynamic Damping, System Frequencies, and Mistuning, Part 1: Theory Under Rotating Conditions T2 - Proceedings of the 15th International Symposium on Unsteady Aerodynamics, Aeroacoustics & Aeroelasticity of Turbomachines, ISUAAAT15, 24-27 September 2018, University of Oxford, UK Y1 - 2018 UR - https://www-docs.b-tu.de/fg-strukturmechanik/public/ISUAAAT15-048-Figaschewsky_Kuehhorn-SystemID_Part1.pdf PB - ISUAAAT Scientific Committee ER - TY - CHAP A1 - Beirow, Bernd A1 - Figaschewsky, Felix A1 - Kühhorn, Arnold T1 - An Inverse Approach to Identify Tuned Aerodynamic Damping, System Frequencies, and Mistuning, Part 2: Application to Blisks at Rest T2 - Proceedings of the 15th International Symposium on Unsteady Aerodynamics, Aeroacoustics & Aeroelasticity of Turbomachines, ISUAAAT15, 24-27 September 2018, University of Oxford, UK Y1 - 2018 UR - https://www-docs.b-tu.de/fg-strukturmechanik/public/ISUAAAT15-021-Beirow_Kuehhorn_Figaschewsky-SystemID_Part2.pdf PB - ISUAAAT Scientific Committee ER - TY - GEN A1 - Beirow, Bernd A1 - Figaschewsky, Felix A1 - Kühhorn, Arnold A1 - Bornholm, Alfons T1 - Vibration Analysis of an Axial Turbine Blisk with Optimized Intentional Mistuning Pattern T2 - Journal of Sound and Vibration N2 - With the objective of attenuating the forced response of an axial turbine blisk for ship Diesel engine applications efforts have been made to increase the aerodynamic damping contribution for the most critical modes. In this regard the potential of intentional mistuning is investigated since it offers the opportunity to ensure a safe operation without a severe loss of aerodynamic performance. Genetic algorithms have been chosen to derive an optimized mistuning pattern resulting in a forced response clearly below that of the tuned counterpart. In order to keep the manufacturing effort within a limit only two possible blade geometries are allowed, which means that an integer optimization problem has been formulated. For the purpose of demonstrating the benefit of the intentional mistuning pattern found, two blisk prototypes have been manufactured: One with and another one without employing intentional mistuning for purposes of comparison. Furthermore, this offers the opportunity for an experimental determination of actually manufactured mistuning and other modal properties as well. The experimental data basis is employed to update structural models, which are well suited to demonstrate the forced response reduction under operational conditions. Finally, the robustness of the gain achieved with intentional mistuning could be proved towards both additional but unavoidable random structural and aerodynamic mistuning. KW - Balde integradet disk KW - Intentional mistuning KW - Vibration KW - Forced response KW - Optimization Y1 - 2019 U6 - https://doi.org/10.1016/j.jsv.2018.10.064 SN - 0022-460X VL - 442 SP - 11 EP - 27 ER - TY - GEN A1 - Figaschewsky, Felix A1 - Hanschke, Benjamin A1 - Kühhorn, Arnold T1 - Efficient Generation of Engine Representative Tip Timing Data Based on a Reduced Order Model for Bladed Rotors T2 - Journal of Engineering for Gas Turbines and Power KW - Vibration KW - Blades KW - Deflection KW - Engines KW - Probes KW - Signals KW - Rotors KW - Uncertainty KW - Errors KW - Simulation Y1 - 2018 U6 - https://doi.org/10.1115/1.4040748 SN - 0742-4795 SN - 1528-8919 VL - 141 IS - 1 ER - TY - CHAP A1 - Koch, Ilja A1 - Beirow, Bernd A1 - Filippatos, Angelos A1 - Kühhorn, Arnold A1 - Gude, Maik T1 - Methodical Approach for Simulation the Vibration of Damaged Fibre Reinforced Composite Rotors Under Consideration of Aerodynamic Influences T2 - 18th European Conference on Composite Materials (ECCM18), Athen (Griechenland), 25.-28. Juni 2018 Y1 - 2018 UR - https://pcoconvin.eventsair.com/QuickEventWebsitePortal/eccm/program/Agenda/AgendaItemDetail?id=258960e5-a867-4c02-b01e-4c997026cf20 ER - TY - GEN A1 - Figaschewsky, Felix A1 - Hanschke, Benjamin A1 - Kühhorn, Arnold T1 - Efficient Generation of Engine Representative Tip Timing Data Based on a Reduced Order Model for Bladed Rotors T2 - ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, Volume 7C: Structures and Dynamics, Oslo, Norway, June 11–15, 2018 N2 - In modern compressors the assessment of blade vibration levels as well as health monitoring of the components are fundamental tasks. Traditionally, this assessment is done by the application of strain gauges to some blades of the assembly. In contrast to strain gauges, blade tip timing (BTT) offers a contactless monitoring of all blades of a rotor and there is no need of a telemetry system. A major issue in the interpretation of BTT data is the heavily undersampled nature of the signal. Usually, newly developed BTT algorithms are tested with sample data created by simplified structural models neglecting many of the uncertainties and disturbing influences of real applications. This work focuses on the creation of simulated BTT datasets as close as possible to real case measurements. For this purpose a subset of nominal system modes (SNM) representation of a compressor rotor is utilized. This model is able to include a large number of features present in real measurements, such as mistuning, static blade deflections due to centrifugal loads, aerodynamic damping and multiple mode resonances. Additionally, manufacturing deviations of the blade geometry, probe positioning errors in the BTT system and noise in the time of arrivals (TOAs) are captured by the BTT simulation environment. The main advantage of the created data is the possibility to steadily increase the signal complexity. Starting with a “perfect” signal the simulation environment is able to add different uncertainties one after the other. This allows the assessment of the influence of different features occurring in real measurements on the performance and accuracy of the analysis algorithms. Finally, a comparison of simulated BTT data and real data acquired from a rig test is shown to validate the presented approach of BTT data generation. Copyright © 2018 by Rolls-Royce Deutschland Ltd & Co KG KW - Engines KW - Rotors Y1 - 2018 SN - 978-0-7918-5115-9 U6 - https://doi.org/10.1115/GT2018-76342 PB - ASME CY - New York, NY ER - TY - CHAP A1 - Beirow, Bernd A1 - Kühhorn, Arnold A1 - Figaschewsky, Felix A1 - Bornholm, Alfons A1 - Repetckii, Oleg V. T1 - Forced Response Reduction of a Blisk by Means of Intentional Mistuning T2 - ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, Volume 7C: Structures and Dynamics, Oslo, Norway, June 11–15, 2018 N2 - The effect of intentional mistuning has been analyzed for an axial turbocharger blisk with the objective of limiting the forced response due to low engine order excitation (LEO). The idea behind the approach was to increase the aerodynamic damping for the most critical fundamental mode in a way that a safe operation is ensured without severely losing aerodynamic performance. Apart from alternate mistuning a more effective mistuning pattern is investigated, which has been derived by means of optimization employing genetic algorithms. In order to keep the manufacturing effort as small as possible only two blade different geometries have been allowed which means that an integer optimization problem has been formulated. Two blisk prototypes have been manufactured for the purpose of demonstrating the benefit of the intentional mistuning pattern identified in this way: A first one with and a second one without employing intentional mistuning. The real mistuning of the prototypes has been experimentally identified. It is shown that the benefit regarding the forced response reduction is retained in spite of the negative impact of unavoidable additional mistuning due to the manufacturing process. Independently, further analyzes have been focused on the robustness of the solution by considering increasing random structural mistuning and aerodynamic mistuning as well. The latter one has been modeled by means of varying aerodynamic influence coefficients (AIC) as part of Monte Carlo simulations. Reduced order models have been employed for these purposes. KW - Engines KW - Manufactoring KW - Simulation KW - Turbochargers KW - Damping KW - Optimization Y1 - 2018 SN - 978-0-7918-5115-9 U6 - https://doi.org/10.1115/GT2018-76584 PB - ASME CY - New York, NY ER - TY - GEN A1 - Weber, Robby A1 - Kühhorn, Arnold T1 - Mistuning Identification Approach With Focus on High-Speed Centrifugal Compressors T2 - ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, Volume 7C: Structures and Dynamics, Oslo, Norway, June 11–15, 2018 N2 - Blade vibrations are one of the main cost drivers in turbo-machinery. Computational blade vibration analysis facilitates an enormous potential to increase the productivity in the design of bladed components. Increasing computing power as well as improved modeling and simulation methods lead to comprehensive calculation results. This allows for a more precise prediction and assessment of experimental data. Usually, in the field of turbomachinery, identical blades are assumed to lower the required computational resources. However, mistuning is unavoidable, since small deviations due to the manufacturing process will lead to slightly different blade behavior. Potential effects such as mode localization and amplification can be treated statistically and have been thoroughly studied in the past. Since then, several reduced order models (ROMs) have been invented in order to calculate the maximum vibration amplitude of a fleet of mistuned blisks. Most commonly, mistuning is thereby modeled by small material deviations from blade to blade, e.g. Young’s modulus or density. Nowadays, it is common knowledge that the level of manufacturing imperfection (referred as level of mistuning) significantly influence mode localization as well as vibration amplification effects. Optical measurements of the geometric deviations of manufactured blades and converting to a high-fidelity finite element model make huge progress. However, to the knowledge of the authors, there is no reliable method, that derives a characteristic quantity from the geometric mistuning, that fits into the mentioned statistically approaches. Therefore, experimental data is needed to quantify the level of mistuning. Several approaches, which isolate blade individual parameters, are used to identify the dynamic behavior of axial compressors and turbines. These methods can be applied to medium-speed centrifugal turbine wheels but tend to fail to evaluate high-speed compressor with splitter blades. This paper briefly presents the original approach and discusses the reasons for failure. Thereafter, a new approach is proposed. Finally the level of mistuning and important quantities to perform a statistical evaluation of a high-speed compressor is shown. Copyright © 2018 by ASME KW - Compressors Y1 - 2018 SN - 978-0-7918-5115-9 U6 - https://doi.org/10.1115/GT2018-75382 PB - ASME CY - New York, NY ER - TY - GEN A1 - Wagner, Frank A1 - Kühhorn, Arnold A1 - Janetzke, Timm A1 - Gerstberger, Ulf T1 - Multi-Objective Optimization of the Cooling Configuration of a High Pressure Turbine Blade T2 - ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, Volume 5C: Heat Transfer Oslo, Norway, June 11–15, 2018 N2 - Due to the increasing turbine inlet temperature and in order to improve the overall efficiency it is necessary to optimize the cooling design of the hot gas components of an aero engine. The current paper discusses the strategy of optimizing a rotor blade cooling configuration of a small civil aero engine, comprising of films and internal turbulators (ribs). An insight into the parametrization is given including the location of the films and ribs as well as the number of the films and ribs. The parameter reduction results in 18 input parameters for the optimizations to limit the number of parameters to an acceptable level. Two optimizations are carried out with the primary objectives of non-dimensional mass flow and overall cooling effectiveness. Different optimization algorithms are used, namely AMGA and NSGA-II, and compared afterwards. A further optimization is carried out with direct objectives of mass flow and mean surface temperature using the AMGA algorithm. The outputs from the optimizations are presented as a pareto-front. These plots are used for a comparison of the optimization algorithms and formulations respectively. Finally, the differences are discussed and the advantages and disadvantages of the algorithms used are highlighted. Copyright © 2018 by Rolls-Royce Deutschland Ltd & Co KG KW - Cooling KW - Turbine Blades KW - High Pressure (Physics) KW - Pareto Optimization Y1 - 2018 SN - 978-0-7918-5110-4 U6 - https://doi.org/10.1115/GT2018-75616 PB - ASME CY - New York, NY ER - TY - CHAP A1 - Weber, Robby A1 - Kühhorn, Arnold T1 - Mistuning und Dämpfung radialer Turbinen- und Verdichterlaufräder T2 - Abschluss- und Zwischenberichte der Forschungsstellen Turbomaschinen, Frühjahrstagung 2018, Tagungsband 2018, Bad Neuenahr Y1 - 2018 SP - 159 EP - 190 PB - Forschungsvereinigung Verbrennungskraftmaschinen e.V. CY - Frankfurt am Main ER -