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  • 1
    Online Resource
    Online Resource
    Aerodynamical and Structural Analysis of Operationally Used Turbine Blades
    Elsevier BV ; 2017
    In:  Procedia CIRP Vol. 59 ( 2017), p. 77-82
    Details
    In: Procedia CIRP, Elsevier BV, Vol. 59 ( 2017), p. 77-82
    Type of Medium: Online Resource
    ISSN: 2212-8271
    URL: Article
    DOI: 10.1016/j.procir.2016.09.023
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2017
    detail.hit.zdb_id: 2674706-6
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  • 2
    Online Resource
    Online Resource
    Operational Modal Analysis of an Axial Compressor Rotor and Casing System for the Online Identification of a Digital Twin
    MDPI AG ; 2022
    In:  Applied Mechanics Vol. 3, No. 1 ( 2022-03-07), p. 244-258
    Details
    In: Applied Mechanics, MDPI AG, Vol. 3, No. 1 ( 2022-03-07), p. 244-258
    Abstract: Modal parameter identification can be a valuable tool in mechanical engineering to predict vibrational behaviour and avoid machine damage during operation. Operational modal analysis is an output-only identification tool motivated by the structural identification of civil engineering structures, which are excited by ambient conditions. This technique is increasingly applied in mechanical engineering in order to characterise the system behaviour during operation as modal parameters can vary under operating conditions. The following study investigates the application of operational modal analysis on an axial compressor under operating conditions. Since the modal parameters of the system change depending on the life history and during the operation of the system, a corresponding data analysis might allow us to identify the present status of the system. Eigenfrequencies and eigenvectors are studied for the use of structural health monitoring approaches. According to the analysis, eigenfrequencies represent robust parameters for the studied purpose. Eigenvectors are sensitive to damages but need further investigation, especially for rotating machinery. This study will help the user to set up a virtual model, which describes the system behaviour for different boundary conditions. This in turn, will provide an accurate prediction of the vibrational behaviour in order to assure a safe operation.
    Type of Medium: Online Resource
    ISSN: 2673-3161
    URL: Article
    DOI: 10.3390/applmech3010017
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 3001011-1
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  • 3
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    Online Resource
    Reduced Order Modeling of Forced Response in a Multistage Compressor Under Mistuning and Aerocoupling
    ASME International ; 2022
    In:  Journal of Engineering for Gas Turbines and Power Vol. 144, No. 11 ( 2022-11-01)
    Details
    In: Journal of Engineering for Gas Turbines and Power, ASME International, Vol. 144, No. 11 ( 2022-11-01)
    Abstract: Vibration amplitudes and fatigue life in multistage turbomachinery are commonly estimated by an investigation of the individual stages. Research is currently extending the scope to include structural and aeroelastic interstage coupling. Both effects have been shown to significantly influence blade vibrations. For safe operation of modern blisk blading with its lower structural damping due to the elimination of frictional contacts at the blade roots, an accurate prediction of the vibration behavior with mistuning is necessary to avoid high cycle fatigue failures. In this paper, a cyclic Craig-Bampton reduction method with a priori interface reduction for multistage rotors is extended to handle aeroelastic effects. This reduced order model efficiently predicts forced response in multistage applications. Aeroelastic multistage simulations are carried out using the harmonic balance method to account for the stage interactions and yield damping and stiffness coefficients, as well as excitation forces. Small structural mistuning is projected onto the tuned system modes of the rotor. The approach is applied to a 2.5-stage compressor configuration. Monte Carlo simulations show the sensitivity of vibration amplitudes to the aeroelastic coupling for mistuning. The aeroelastic interstage coupling is found to originate mainly from acoustic mode propagation between the stages. The fatigue of rotor blades is significantly affected by multistage interactions since vibration amplitudes increase due to the superposition of the responses of multiple modes. This leads to the conclusion that aeroelastic multistage effects need to be incorporated in future design procedures to allow for an accurate prediction of fatigue life.
    Type of Medium: Online Resource
    ISSN: 0742-4795 , 1528-8919
    URL: Article
    DOI: 10.1115/1.4055368
    Language: English
    Publisher: ASME International
    Publication Date: 2022
    detail.hit.zdb_id: 2010437-6
    detail.hit.zdb_id: 165371-4
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  • 4
    Online Resource
    Online Resource
    Methodology for evaluating hot gas path defects in an exhaust jet
    Elsevier BV ; 2014
    In:  Aerospace Science and Technology Vol. 39 ( 2014-12), p. 120-127
    Details
    In: Aerospace Science and Technology, Elsevier BV, Vol. 39 ( 2014-12), p. 120-127
    Type of Medium: Online Resource
    ISSN: 1270-9638
    URL: Article
    DOI: 10.1016/j.ast.2014.08.011
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2014
    detail.hit.zdb_id: 2014638-3
    SSG: 16,12
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  • 5
    Online Resource
    Online Resource
    Time Resolved Full-Annulus Computations of a Turbine with Inhomogeneous Inlet Conditions
    Gas Turbine Society of Japan ; 2012
    In:  International Journal of Gas Turbine, Propulsion and Power Systems Vol. 4, No. 2 ( 2012), p. 1-7
    Details
    In: International Journal of Gas Turbine, Propulsion and Power Systems, Gas Turbine Society of Japan, Vol. 4, No. 2 ( 2012), p. 1-7
    Type of Medium: Online Resource
    ISSN: 1882-5079
    URL: Article
    DOI: 10.38036/jgpp.4.2_1
    Language: English
    Publisher: Gas Turbine Society of Japan
    Publication Date: 2012
    detail.hit.zdb_id: 2399918-4
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  • 6
    Online Resource
    Online Resource
    Early Assessment of Defects and Damage in Jet Engines
    Elsevier BV ; 2013
    In:  Procedia CIRP Vol. 11 ( 2013), p. 328-333
    Details
    In: Procedia CIRP, Elsevier BV, Vol. 11 ( 2013), p. 328-333
    Type of Medium: Online Resource
    ISSN: 2212-8271
    URL: Article
    DOI: 10.1016/j.procir.2013.07.022
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2013
    detail.hit.zdb_id: 2674706-6
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  • 7
    Online Resource
    Online Resource
    Load Pulses on Wind Turbine Structures Caused by Tower Interference
    SAGE Publications ; 2009
    In:  Wind Engineering Vol. 33, No. 6 ( 2009-12), p. 555-570
    Details
    In: Wind Engineering, SAGE Publications, Vol. 33, No. 6 ( 2009-12), p. 555-570
    Abstract: One of the factors which causes cyclic loading on wind turbines is the influence of the tower on the aerodynamic performance of the rotor. Although a flickering in the power output of the turbine can be observed, the load pulses acting on the blades, the main shaft, the support bearings, the power transmission system, and the tower are potentially more troublesome. Aerodynamic modelling of this interaction by means of symmetric tower flow models is not capable of capturing all the effects present such as aerodynamic coupling of the tower and blades, tower wake meandering, lateral tower loads, and break-up of the rotor wake. These effects become more important for highly loaded rotors or for very flexible blades for which the gap between the rotor and the tower is small. In this paper, the results of 2D CFD simulations are used in order to correct the predictions of traditional BEM methods. Two turbulence models are used and their advantages and drawbacks are discussed. It is shown that the rotor also induces a periodic lateral loading on the tower and a shift in frequency of the vortex street behind the tower. It is also shown that the tower causes a break up of the turbulent wake of the rotor. The BEM formulation including this correction is validated against experimental data available in the literature. The method is applied to calculate the effects on a test blade geometry.
    Type of Medium: Online Resource
    ISSN: 0309-524X , 2048-402X
    URL: Article
    DOI: 10.1260/0309-524X.33.6.555
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2009
    detail.hit.zdb_id: 2026065-9
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  • 8
    Online Resource
    Online Resource
    Optimal Application of Riblets on Compressor Blades and Their Contamination Behavior
    ASME International ; 2013
    In:  Journal of Turbomachinery Vol. 135, No. 1 ( 2013-01-01)
    Details
    In: Journal of Turbomachinery, ASME International, Vol. 135, No. 1 ( 2013-01-01)
    Abstract: During the last decades, riblets have shown a potential for viscous drag reduction in turbulent boundary layers. Several investigations and measurements of skin-friction in the boundary layer over flat plates and on turbomachinery-type blades with ideal riblet geometry have been reported in the literature. The question of where riblets must be applied on the surface of a compressor blade is still not sufficiently answered. In a first step, the profile loss reduction by ideal triangular riblets with a trapezoidal groove and a constant geometry along the surface on the suction and pressure sides of a compressor blade is investigated. The results show a higher potential on the profile loss reduction by riblets on the suction side. In a second step, the effect of laser-structured ribs on the laminar separation bubble and the influence of these structures on the laminar boundary layer near the leading edge are investigated. After clarifying the best choices where riblets should be applied on the blade surface, a strategy for locally adapted riblets is presented. The suction side of a compressor blade is laser-structured with segmented riblets with a constant geometry in each segment. The measured profile loss reduction shows the increasing effect on the profile loss reduction of this locally adapted structure compared to a constant riblet-geometry along the surface. Furthermore, the particle deposition on a riblet-structured compressor blade is investigated and compared to the particle deposition on a smooth surface. Results show a primary particle deposition on the riblet tips followed by an agglomeration. The particle deposition on the smooth surface is stochastic.
    Type of Medium: Online Resource
    ISSN: 0889-504X , 1528-8900
    URL: Article
    DOI: 10.1115/1.4006518
    Language: English
    Publisher: ASME International
    Publication Date: 2013
    detail.hit.zdb_id: 56356-0
    detail.hit.zdb_id: 2010462-5
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  • 9
    Online Resource
    Online Resource
    Transition Modeling for Vortex Generating Jets on Low-Pressure Turbine Profiles
    ASME International ; 2013
    In:  Journal of Turbomachinery Vol. 135, No. 1 ( 2013-01-01)
    Details
    In: Journal of Turbomachinery, ASME International, Vol. 135, No. 1 ( 2013-01-01)
    Abstract: Steady blowing vortex generating jets (VGJ) on highly-loaded low-pressure turbine profiles have shown to be a promising way to decrease total pressure losses at low Reynolds-numbers by reducing laminar separation. In the present paper, the state of the art turbomachinery design code TRACE with RANS turbulence closure and coupled γ-ReΘ transition model is applied to the prediction of typical aerodynamic design parameters of various VGJ configurations in steady simulations. High-speed cascade wind tunnel experiments for a wide range of Reynolds-numbers, two VGJ positions, and three jet blowing ratios are used for validation. Since the original transition model overpredicts separation and losses at Re2is≤100·103, an extra mode for VGJ induced transition is introduced. Whereas the criterion for transition is modeled by a filtered Q vortex criterion the transition development itself is modeled by a reduction of the local transition-onset momentum-thickness Reynolds number. The new model significantly improves the quality of the computational results by capturing the corresponding local transition process in a physically reasonable way. This is shown to yield an improved quantitative prediction of surface pressure distributions and total pressure losses.
    Type of Medium: Online Resource
    ISSN: 0889-504X , 1528-8900
    URL: Article
    DOI: 10.1115/1.4006421
    Language: English
    Publisher: ASME International
    Publication Date: 2013
    detail.hit.zdb_id: 56356-0
    detail.hit.zdb_id: 2010462-5
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  • 10
    Online Resource
    Online Resource
    Flow Patterns in High Pressure Steam Turbines During Low-Load Operation
    ASME International ; 2014
    In:  Journal of Turbomachinery Vol. 136, No. 6 ( 2014-06-01)
    Details
    In: Journal of Turbomachinery, ASME International, Vol. 136, No. 6 ( 2014-06-01)
    Abstract: Due to the legislative efforts of promoting renewable energy sources, electricity from these sources is preferentially fed into the electrical grid. This requires more frequent part- and low-load operation of peak- and even of base-load power plants to compensate for the varying energy output of renewable energy sources. These requirements ultimately lead to an increased part- and low-load operation not only of low pressure (LP) steam turbines but also of high pressure (HP) steam turbines, putting them at risk of damage due to windage, i.e., strongly separated flow with associated heat generation. For the first time measurements of the steady-state flow field in a 7-stage model air turbine with a modern HP steam turbine blading are conducted in order to extend the understanding of the part- and low-load operation from LP to HP steam turbines. In comparison with LP steam turbines, similar flow fields develop during windage. However, differences exist especially concerning the vortex development in front of the turbine vane rows. The present, geometrically realistic 7-stage turbine, unlike other turbines investigated before, does not show these vortices, which is explained by the shape of the vane passages of this turbine blading. Furthermore, steady-state flow field measurements at different rotor speeds show that the flow coefficient can be used as a nondimensional parameter for maintaining flow field similarity even in part- or low-load operation. Additionally, unsteady circumferential pressure measurements show the existence of pressure perturbations moving circumferentially in front of the stage 7 blades. Seven pressure perturbations moving at 60% of the rotor speed are identified. Due to the shrouded design of the HP steam turbine blading used, the pressure perturbations are not due to tip leakage vortices. Hence, they are identified as features which are similar to “Rotating Stall” cells known from compressors.
    Type of Medium: Online Resource
    ISSN: 0889-504X , 1528-8900
    URL: Article
    DOI: 10.1115/1.4025162
    Language: English
    Publisher: ASME International
    Publication Date: 2014
    detail.hit.zdb_id: 56356-0
    detail.hit.zdb_id: 2010462-5
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