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  • 1
    Online Resource
    Online Resource
    Global Power and Propulsion Society ; 2023
    In:  Journal of the Global Power and Propulsion Society Vol. 7 ( 2023-6-9), p. 166-176
    In: Journal of the Global Power and Propulsion Society, Global Power and Propulsion Society, Vol. 7 ( 2023-6-9), p. 166-176
    Abstract: Micro Gas Turbines (MGTs) are nowadays largely used for electrical and thermal energy production in small buildings and households. Their reliability and compactness allow them to operate for thousands of hours with minimal maintenance. However, the long exposure at high temperatures in combustion chambers can promote creep, which can induce thermal fatigue and potential failure of these components. Creep-induced damage in MGTs has not yet been thoroughly investigated, due to the lack of numerical tools able to model these strongly coupled phenomena. This study presents the development of a Fortran-based subroutine integrated into ANSYS APDL. The code allows for a life assessment based on the Lemaitre-Chaboche creep damage model. Secondary creep and stress relaxation are modeled for the high-temperature resistant alloy Inconel718. A new set of temperature-dependent parameters for the Norton equation is provided, and the method to obtain these parameters from creep rupture tests is outlined. The model is validated and shows good agreement with experimental data. The subroutine correctly reproduces visco-plasticity, stress relaxation and damage under typical MGTs operating temperatures. This model constitutes the foundation of a life-assessment analysis for combustion chambers. The results highlight the impact of temperature and creep on the component’s life and the importance of integrating life assessment analysis into the preliminary design of combustion chambers.
    Type of Medium: Online Resource
    ISSN: 2515-3080
    Language: Unknown
    Publisher: Global Power and Propulsion Society
    Publication Date: 2023
    detail.hit.zdb_id: 2962119-7
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  • 2
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2023
    In:  Flow, Turbulence and Combustion Vol. 111, No. 2 ( 2023-08), p. 603-640
    In: Flow, Turbulence and Combustion, Springer Science and Business Media LLC, Vol. 111, No. 2 ( 2023-08), p. 603-640
    Abstract: To enable risk informed decisions in the simulation-based design and development of novel combustors, uncertainties in the simulation results must be considered. However, due to the high computational costs for their quantification, these uncertainties are commonly not taken into account. Therefore, this work aims at applying an efficient methodology for uncertainty quantification based on Polynomial Chaos Expansion to a semi-technical spray burner reflecting characteristics typically found in modern aeroengine combustors. This requires accurate treatment of the multicomponent liquid fuel, a combustion model relying on finite rate chemistry and a scale resolving hybrid turbulence model to account for highly unsteady flow features and combustion. To overcome the need for costly experimental data for the spray boundary conditions, an algebraic primary breakup model is utilized. The resulting reduction in a priori information is compensated through probabilistic modeling and uncertainty quantification. Due to their importance in the design process, temperature distribution in the gas phase as well as the flame position are considered as the primary quantities of interest. For these quantities of interest, moderate uncertainties are found in the probabilistic simulation results. Further, the predictive capability of the simulation model under uncertainties is quantitively assessed by defining accurary metrics for the gas phase temperature prediction. The study further reveals that the imposed input uncertainties affect quantities of interest in both the dispersed and the gas phase through phase coupling effects.
    Type of Medium: Online Resource
    ISSN: 1386-6184 , 1573-1987
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 1492282-4
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  • 3
    Online Resource
    Online Resource
    Elsevier BV ; 2022
    In:  Procedia Structural Integrity Vol. 42 ( 2022), p. 1728-1735
    In: Procedia Structural Integrity, Elsevier BV, Vol. 42 ( 2022), p. 1728-1735
    Type of Medium: Online Resource
    ISSN: 2452-3216
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2022
    detail.hit.zdb_id: 2880750-9
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  • 4
    In: Combustion and Flame, Elsevier BV, Vol. 213 ( 2020-03), p. 26-38
    Type of Medium: Online Resource
    ISSN: 0010-2180
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2020
    detail.hit.zdb_id: 2000795-4
    detail.hit.zdb_id: 240116-2
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  • 5
    In: Energies, MDPI AG, Vol. 14, No. 3 ( 2021-01-21), p. 537-
    Abstract: An atmospheric prototype burner is studied with numerical and experimental tools. The burner system is designed for operation in a hybrid power plant for decentralized energy conversion. In order to realize such a coupled system, a reliable combustion system has to be established. Numerical and experimental findings in the presented study demonstrate the capabilities of the novel burner system in suitable operation conditions. In this system, a solid oxide fuel cell (SOFC) is mounted upstream of the burner in the gas turbine system. The combination of both realizes a large operational flexibility with comparably high overall efficiency. Since the combustor is operated with SOFC off-gas, several challenges arise. Low calorific combustion needs careful burner design and numerical modeling, since the heat-loss mechanisms occur to be in the order of magnitude of thermal power output. Thus, different modeling strategies are discussed in the paper. The numerical studies are compared with experimental results and high-quality simulation results complement limited measured findings with easy-to-use low fidelity RANS models. A priori measurements are employed for the selection of investigation points. It is shown that the presented combustor system is able to cover low-calorific combustion over a large range of operation conditions, despite major heat-loss effects, which are characterized by means of numerical CFD (Computational Fluid Dynamics) modeling.
    Type of Medium: Online Resource
    ISSN: 1996-1073
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2437446-5
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  • 6
    Online Resource
    Online Resource
    Wissenschaftliche Verlagsgesellschaft mbH ; 2017
    In:  Acta Acustica united with Acustica Vol. 103, No. 2 ( 2017-03-01), p. 262-275
    In: Acta Acustica united with Acustica, Wissenschaftliche Verlagsgesellschaft mbH, Vol. 103, No. 2 ( 2017-03-01), p. 262-275
    Type of Medium: Online Resource
    ISSN: 1610-1928
    Language: English
    Publisher: Wissenschaftliche Verlagsgesellschaft mbH
    Publication Date: 2017
    detail.hit.zdb_id: 119-3
    detail.hit.zdb_id: 2078656-6
    SSG: 7,11
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  • 7
    In: E3S Web of Conferences, EDP Sciences, Vol. 113 ( 2019), p. 02016-
    Abstract: A demonstrator system for a hybrid power plant is currently being built at DLR, designed for an electrical power output level of 30 kW. Since the very low energy dense exhaust gas of the fuel cell anode side represents the fuel for the combustion chamber in this application, a low calorific SOFC off-gas combustor was developed at DLR specifically for this use case. With thorough investigations on the atmospheric test rig, the expected operational range of the combustor was quantified in preceding works. Now, a novel machine design, including dilution air with an adjustable air split configuration is derived to validate the gathered information on the micro gas turbine test rig under pressurized machine conditions. This work explains the design of the combustion system and addresses the different design features specifically implemented for this use case. Since simplifications had to be made for the atmospheric combustor prototype, a significant positive influence on the operational envelope is expected with the transition to the machine configuration.
    Type of Medium: Online Resource
    ISSN: 2267-1242
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2019
    detail.hit.zdb_id: 2755680-3
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  • 8
    Online Resource
    Online Resource
    MDPI AG ; 2022
    In:  Applied Sciences Vol. 12, No. 12 ( 2022-06-15), p. 6069-
    In: Applied Sciences, MDPI AG, Vol. 12, No. 12 ( 2022-06-15), p. 6069-
    Abstract: Currently, Micro Gas Turbines (MGTs) are widely used in small buildings, such as offices, hospitals, or households, in which electricity and thermal energy are needed. Their reliability, flexibility, and compactness allow these devices to operate in different regimes to fulfill the power demand. The opportunity to operate at partial-load is deeply investigated in this paper. To cope with the fast, unpredictable demand of energy, thermal storage and batteries are most commonly installed. The potential of these two components for the operating cost is also investigated in this paper in order to provide guidelines on their sizing. Moreover, the thermal and electrical energy demands depend on different factors such as building size, weather, day of the week, and location, all modeled in this work; the possibility to buy and feed electricity into the grid adds a further variable to the economic analysis. All these factors were considered in this study and led to the creation of an optimization algorithm, which was able to determine the optimal operating profile of the system for every single scenario. The operational optimization of a micro gas turbine, the MTT Enertwin, is presented. Data from experimental measurements were implemented in the algorithm in order to characterize the system performance. Concerning the input power demands, data for Germany according to the norm VDI 4655 were considered; hence, the results are formally limited to this region. However, considerations of batteries and thermal storage were broadly valid; also, the results can be of international interest in countries with a similar climate and habits. With this study, it is shown that the optimal operational strategy is in the vast majority of cases the full-load, with savings up to 20% with respect to partial-load. Furthermore, batteries between 1.5 and 2 kWh constitute the best compromise between installation costs and savings; the investment can be generally paid off in less than 3 years. Finally, a threshold of 400 L for thermal storage was identified.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2704225-X
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  • 9
    Online Resource
    Online Resource
    SAGE Publications ; 2017
    In:  International Journal of Spray and Combustion Dynamics Vol. 9, No. 4 ( 2017-12), p. 330-348
    In: International Journal of Spray and Combustion Dynamics, SAGE Publications, Vol. 9, No. 4 ( 2017-12), p. 330-348
    Abstract: A stochastic, hybrid computational fluid dynamics/computational combustion acoustics approach for combustion noise prediction is applied to the PRECCINSTA laboratory scale combustor (prediction and control of combustion instabilities in industrial gas turbines). The numerical method is validated for its ability to accurately reproduce broadband combustion noise levels from measurements. The approach is based on averaged flow field and turbulence statistics from computational fluid dynamics simulations. The three-dimensional fast random particle method for combustion noise prediction is employed for the modelling of time-resolved dynamics of sound sources and sound propagation via linearised Euler equations. A comprehensive analysis of simulated sound source dynamics is carried out in order to contribute to the understanding of combustion noise formation mechanisms. Therefrom gained knowledge can further on be incorporated for the investigation of onset of thermoacoustic phenomena. The method-inherent stochastic Langevin ansatz for the realisation of turbulence related source decay is analysed in terms of reproduction ability of local one- and two-point statistical input and therefore its applicability to complex test cases. Furthermore, input turbulence statistics are varied, in order to investigate the impact of turbulence on the resulting sound pressure spectra for a swirl stabilised, technically premixed combustor.
    Type of Medium: Online Resource
    ISSN: 1756-8277 , 1756-8285
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2017
    detail.hit.zdb_id: 2504645-7
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  • 10
    Online Resource
    Online Resource
    American Institute of Aeronautics and Astronautics (AIAA) ; 2017
    In:  AIAA Journal Vol. 55, No. 7 ( 2017-07), p. 2481-2488
    In: AIAA Journal, American Institute of Aeronautics and Astronautics (AIAA), Vol. 55, No. 7 ( 2017-07), p. 2481-2488
    Type of Medium: Online Resource
    ISSN: 0001-1452 , 1533-385X
    Language: English
    Publisher: American Institute of Aeronautics and Astronautics (AIAA)
    Publication Date: 2017
    detail.hit.zdb_id: 240221-X
    detail.hit.zdb_id: 2032720-1
    SSG: 16,12
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