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 - 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 - 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 - GEN A1 - Hanschke, Benjamin A1 - Kühhorn, Arnold A1 - Schrape, Sven A1 - Giersch, Thomas T1 - Consequences of Borescope Blending Repairs on Modern HPC Blisk Aeroelasticity T2 - Journal of Turbomachinery N2 - Objective of this paper is to analyze the consequences of borescope blending repairs on the aeroelastic behavior of a modern high pressure compressor (HPC) blisk. To investigate the blending consequences in terms of aerodynamic damping and forcing changes, a generic blending of a rotor blade is modeled. Steady-state flow parameters like total pressure ratio, polytropic efficiency, and the loss coefficient are compared. Furthermore, aerodynamic damping is computed utilizing the aerodynamic influence coefficient (AIC) approach for both geometries. Results are confirmed by single passage flutter (SPF) simulations for specific interblade phase angles (IBPA) of interest. Finally, a unidirectional forced response analysis for the nominal and the blended rotor is conducted to determine the aerodynamic force exciting the blade motion. The frequency content as well as the forcing amplitudes is obtained from Fourier transformation of the forcing signal. As a result of the present analysis, the change of the blade vibration amplitude is computed. Y1 - 2019 U6 - https://doi.org/10.1115/1.4041672 SN - 1528-8900 SN - 0889-504X VL - 141 IS - 2 ER - TY - GEN A1 - Hanschke, Benjamin A1 - Klauke, Thomas A1 - Kühhorn, Arnold T1 - The Effect of Foreign Object Damage on Compressor Blade High Cycle Fatigue Strength T2 - ASME Turbo Expo 2017, GT2017-63559, June 26-30, 2017, Charlotte, NC, USA, Volume 7A N2 - For a considerable amount of time blade integrated disks (blisks) are established as a standard component of high pressure compressors (HPCs) in aero engines. Due to the steady requirement to increase the efficiency of modern HPCs, blade profiles get thinned out and aerodynamic stage loading increases. Ever since, aerofoil design has to balance structural and aerodynamic requirements. One particularity of aero engines is the possibility to ingest different kinds of debris during operation and some of those particles are hard enough to seriously damage the aerofoil. Lately, a growing number of blisk-equipped aero engines entered service and the question of foreign object damage (FOD) sensitivity relating to compressor blade high cycle fatigue (HCF) has emerged. Correct prediction of fatigue strength drop due to a FOD provides a huge chance for cost cutting in the service sector as on-wing repairs (e.g. borescope blending) are much more convenient than the replacement of whole blisks and corresponding engine strips. The aim of this paper is to identify critical FOD-areas of a modern HPC stage and to analyze the effects of stress concentrations — caused by FOD — on the fatigue strength. A process chain has been developed, that automatically creates damaged geometries, meshes the parts and analyses the fatigue strength. Amplitude frequency strength (af-strength) has been chosen as fatigue strength indicator owing to the fact, that amplitudes and frequencies of blade vibrations are commonly measured either by blade tip timing or strain gauges. Furthermore, static and dynamic stress concentrations in damaged geometries compared to the reference design were computed. A random variation of input parameters was performed, such as the radial damage position at blade leading edge and damage diameter. Based on results of the different samples, correlations of input parameters and the fatigue strength drop have been investigated. Evaluation shows a significant mode dependence of critical blade areas with a large scatter between drops in fatigue strength visible for mode to mode comparison. Keeping in mind the necessity of fast response times in the in-service sector, FOD sensitivity computations could be performed for all blade rows of the HPC — including the analysis of possible borescope blending geometries — in the design stage. Finally, the actual amplitude frequency levels (af-levels) of the modes excited during operation have to be appropriately taken into consideration. For example, a pronounced af-strength drop due to a FOD may not be critical for safe engine operations because the observed mode is excited by small af-levels during operation. Hence, the endurance ratio — a quotient of af-level and af-strength — is used as assessment criterion. Copyright © 2017 by ASME KW - Compressors KW - Blades KW - High cycle fatigue KW - Damage Y1 - 2017 SN - 978-0-7918-5092-3 U6 - https://doi.org/10.1115/GT2017-63599 PB - ASME CY - New York, NY ER - TY - GEN A1 - Krause, Christoph A1 - Stelldinger, Marco A1 - Hanschke, Benjamin A1 - Kühhorn, Arnold A1 - Giersch, Thomas T1 - Asynchronous Response Analysis of Non-Contact Vibration Measurements on Compressor Rotor Blades T2 - ASME Turbo Expo 2017, GT2017-63200, June 26-30, 2017, Charlotte, NC, USA, Volume 7B N2 - Although the research in non-intrusive techniques for the measurement of vibration have made major progress since the beginning in the 1960’s, they are still mainly used as additional tool to the common strain gauges. Therefore, there is still a great deal of interest in the improvement of such non-contact vibration measurement techniques, to replace the intrusive ones with alternative techniques. One possibility to monitor all blades at once is blade tip-timing. The probes for a blade tip-timing measurement system are mounted circumferentially in the engine casing to log the passing times of the rotor blades. These logged time data will be compared with theoretically calculated passing times. The deviation between measured and calculated passing times can be transformed to blade displacement values. In recent years, several methods to analyse the acquired vibration data have been developed and improved. They are directed to evaluate synchronous and asynchronous blade vibration events. This paper focuses on the identification of asynchronous vibrations on rotor blades using blade tip-timing. Taking the data from all probes into account gives an opportunity to determine the vibration of each single blade. Due to the usage of a research test rig, all measurement data could be acquired in simulated real case operation scenarios. Analysis data were evaluated with a developed post processing routine based on a Fourier transformation algorithm coupled with a least square fitting procedure. Since compressor surge represents one of the most critical non synchronous events during compressor operation, in this paper a special interest is paid to the analysis of compressor surges. Vibration frequencies revealed during surge investigation will be compared with simultaneously measured strain gauge data to ensure the reliability of blade tip-timing measurement and analysis. To explain the results in more detail, the possibility of a blade damaged triggered shift of the blade characteristic frequency is shown. The most promising result of the analysis is the close correlation between the identified vibration frequencies of compressor surge events and the afterwards determined frequency mistuning and crack distributions. Blade damage becomes visible through increasing deviation between characteristic frequencies of different blades as result of multiple surge events. In addition, with the comparison of mean frequency records over each single surge among each other it is possible to restrict the blade damage time. Subsequently, the possibility to develop a process routine to predict blade damage during compressor test series could arise. KW - Compressors KW - Rotors KW - Blades KW - Vibration measurement Y1 - 2017 SN - 978-0-7918-5093-0 U6 - https://doi.org/10.1115/GT2017-63200 PB - ASME CY - New York, NY ER -