TY - GEN A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Stochastische Modellierung einer Methan/Luft Freistrahl-Flamme mit detaillierter Chemie T2 - 30. Deutscher Flammentag, Hannover-Garbsen, 28-29 September 2021 N2 - Die vorliegende Arbeit befasst sich mit der stochastischen Modellierung einer Methan/Luft Freistrahl-Flamme unter Verwendung des One-Dimensional Turbulence (ODT) Modells. Bei der untersuchten Cabra-Brennerkonfiguration handelt es sich um ein offenes System, bei welchem ein vorgemischter Methan/Luft Freistrahl von einer zentral angeordneten Düse in eine Umgebungsströmung aus heißen Verbrennungsgasen strömt. Das One-Dimensional Turbulence Modell ist ein stochastisches und abbildungsbasiertes Modell, welches die molekulare Diffusion und Reaktionskinetik durch sich zeitlich entwickelnde, deterministische Erhaltungsgleichungen berücksichtigt und entlang eines eindimensionalen Rechengebietes vollständig auflöst. Die Besonderheit von ODT liegt in der Modellierung der turbulenten Advektion über zufällig auftretende Wirbelereignisse, welche den fundamentalen Erhaltungseigenschaften unterliegen. Für die Abbildung der Methan/Luft Verbrennungschemie wird ein reduzierter Mechanismus mit 19 Spezies und 15 Reaktionen und ein detaillierter Mechanismus mit 53 Spezies und 325 Reaktionen eingesetzt. Die gezeigten vorläufigen ODT-Simulationsergebnisse der Methan/Luft Freistrahl-Flamme beinhalten Mittellinienprofile, radiale Profile, Streudiagramme und zweidimensionale Visualisierungen der Freistrahl-Flamme, welche mit einer zylindrischen Formulierung von ODT erzeugt wurden. Zu Vergleichszwecken werden die Simulationsergebnisse experimentellen Messungen gegenübergestellt. Obwohl die Simulation von reaktiven Freistrahl-Flammen keinen neuen Anwendungsfall von ODT darstellt, ist die akkurate Wiedergabe des sensiblen Zusammenspiels des zunächst unverbrannten Freistrahls mit der heißen Umgebungsströmung eine Herausforderung für das Modell. In der durchgeführten Studie konnte gezeigt werden, dass die mittels ODT erzeugten Statistiken eine beachtlich gute Übereinstimmung mit den Vergleichsdaten aufweisen. Im Hinblick auf die reduzierte Dimensionalität von ODT, die Qualität der erzielten Ergebnisse und die erforderliche Rechenleistung, stellt ODT ein attraktives Modell zur Simulation von turbulenten und reaktiven Strömungen dar. Y1 - 2021 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_2021_Flammentag.pdf ER - TY - GEN A1 - Kerstein, Alan R. A1 - Lignell, David O. A1 - Schmidt, Heiko A1 - Starick, Tommy A1 - Wheeler, Isaac A1 - Behrang, Masoomeh T1 - Using Hips As a New Mixing Model to Study Differential Diffusion of Scalar Mixing in Turbulent Flows T2 - 2021 AIChE Annual Meeting N2 - Mixing two or more streams is ubiquitous in chemical processes and industries involving turbulent liquid or gaseous flows. Modeling turbulent mixing flows is complicated due to a wide range of time and length scales, and non-linear processes, especially when reaction is involved. On the other hand, in turbulent reacting flows, sub-grid scales need to be resolved accurately because they involve reactive and diffusive transport processes. Transported PDF methods use mixing models to capture the interaction in the sub-grid scales. Several models have been used with varying success. In this study, we present a novel model for simulation of turbulent mixing called Hierarchical Parcel Swapping (HiPS). The HiPS model is a stochastic mixing model that resolves a full range of time and length scales with the reduction in the complexity of modeling turbulent reacting flows. This model can be used as a sub-grid mixing model in PDF transport methods, as well as a standalone model. HiPS can be applied to transported scalars with variable Schmidt numbers to capture the effect of differential diffusion which is important for modeling scalars with low diffusivity like soot. We present an overview of the HiPS model, its formulation for variable Schmidt number flows, and then present results for evaluating the turbulence properties including the scalar energy spectra, the scalar dissipation rate, and Richardson dispersion. These model developments are an important step in applying HiPS to more complex flow configurations. Y1 - 2021 UR - https://plan.core-apps.com/aiche2021/event/002309c77cf108fff1a6a8a101a07ebd ER - TY - GEN A1 - Starick, Tommy A1 - Lignell, David O. A1 - Schmidt, Heiko T1 - Stochastic Modeling of a Lifted Methane/Air Jet Flame with Detailed Chemistry T2 - 91th Annual Meeting of the International Association of Applied Mathematics and Mechanics March 15-19, 2021 Kassel, DE Y1 - 2021 UR - https://onlinelibrary.wiley.com/doi/epdf/10.1002/pamm.202100237 U6 - https://doi.org/10.1002/pamm.202100237 ER - TY - GEN A1 - Xie, Tianxiao A1 - Starick, Tommy A1 - Mosgow, Anatol A1 - Berg, Heinz Peter A1 - Höschler, Klaus A1 - Schmidt, Heiko T1 - Thermofluiddynamic pre-design of a primary surface heat exchanger under the influence of heat radiation using 1D/3D coupled simulation method T2 - NAFEMS World Congress 2021, online, 25-29. Oktober 2021 N2 - Within the Framework of the "TurboFuelCell (TFC)" a highly integrated and compact energy conversion system based on Micro Gas Turbine Solid Oxide Fuel Cell (MGT-SOFC) hybrid process is being developed by the team at BTU-Cottbus Senftenberg. This work focuses on the extension of the pre-design process of a primary surface heat exchanger (PSHX), which is a key component for the coupling between MGT and SOFC, using an 1D/3D hybrid simulation method for the understanding of its behaviour under the influence of heat radiation. In a MGT-SOFC hybrid process the high temperature heat exchanger plays an important role in preheating the fresh air to a minimum operation temperature necessary for SOFC. Due to the special location of this PSHX in the TFC, it is constantly exposed to heat radiation from the SOFC module, which requires additional consideration of its influence for better model accuracy. A first design, which is later extended through an 1D Flow network model, based on 𝜖 − 𝑁𝑇𝑈 method is presented. A complete 3D-CFD simulation with consideration of heat radiation is initially employed for the whole flow process to examine the first design. However, this approach proves to be highly computationally expensive due to the large dimensional difference between the plenum for cathode exhaust air and the fine channels in the PSHX. To reduce the computational effort, the flow and heat transfer in the PSHX is modelled by 1D elements. The flow in the plenum is simulated by 3D-CFD, which better accounts for convection and thermal radiation. A comparison between 3D-CFD and 1D/3D hybrid model is performed. A significant reduction of simulation time and computing resources can be achieved for well calibrated hybrid model without compromising on accuracy. In the talk, the effect of insulation layer thickness variations on the heat transfer on the plenum side due to heat radiation and their influence on the heat exchanger efficiency are discussed. Consequently, design improvements are realized based on the previous findings. Finally, the 1D/3D hybrid simulation method is evaluated and prepared for the general applications in thermal management of machines based on coupled MGT-SOFC process. Y1 - 2021 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_2021_NAFEMS_World_Congress_Manuscript.pdf UR - https://agenda.nwc21.org/session.php?s=B5 ER -