FG Numerische Fluiddynamik

13 Items

Recent Submissions
Adjoint-based optimisation of detonation initiation by a focusing shock wave

Bengoechea, Sergio ; Reiss, Julius ; Lemke, Mathias ; Sesterhenn, Jörn (2021-03-25)

An optimisation study of a shock-wave-focusing geometry is presented in this work. The configuration serves as a reliable and deterministic detonation initiator in a pulsed detonation engine. The combustion chamber consists of a circular pipe with one convergent–divergent axisymmetric nozzle, acting as a focusing device for an incoming shock wave. Geometrical changes are proposed to reduce the ...

Numerical investigation of detonation initiation by a focusing shock wave

Bengoechea Lozano, Sergio ; Reiss, Julius ; Lemke, Mathias ; Sesterhenn, Jörn (2020-10-06)

This work presents a numerical study of detonation initiation by means of a focusing shock wave. The investigated geometry is a part of a pulsed detonation combustion chamber, consisting of a circular pipe in which the flow is obstructed by a single convergent–divergent axisymmetric nozzle. This obstacle acts as a focusing device for an incoming shock wave, serving as a low-energy detonation in...

Space-time-data of a 1D model of a puls detonation combustor

Reiss, Julius ; Lemke, Mathias (2020-09-22)

The data and the shifts to compensate the transports is loaded in the Matlab script readData.m where the data structure is also explained. The additional file Qfull.mat contains the original data with the resolution used in the simulation. It is down-scaled by taking every third point in space and every hundredth point in time for the shifted POD. It reduces the data size, but produces in the f...

Maximum Entropy Analysis of Flow Networks: Theoretical Foundation and Applications

Niven, Robert K. ; Abel, Markus ; Schlegel, Michael ; Waldrip, Steven H. (2019-08-08)

The concept of a “flow network”—a set of nodes and links which carries one or more flows—unites many different disciplines, including pipe flow, fluid flow, electrical, chemical reaction, ecological, epidemiological, neurological, communications, transportation, financial, economic and human social networks. This Feature Paper presents a generalized maximum entropy framework to infer the state ...

Simulation and modeling of a Helmholtz resonator under grazing turbulent flow

Stein, Lewin (2019)

When gas flows along a surface containing a cavity or gap, this fluid-dynamical process is likely linked with acoustical effects. Primarily, in the transport and energy sector, the phenomenon occurs frequently: gas flows around land and air vehicles or streams inside duct systems and engines. A key challenge for these examples is either to prevent cavity noise before it arises or to reduce exis...

Compressible starting jet: pinch-off and vortex ring–trailing jet interaction

Peña Fernández, Juan José ; Sesterhenn, Jörn (2017)

The dominant feature of the compressible starting jet is the interaction between the emerging vortex ring and the trailing jet. There are two types of interaction: the shock–shear layer–vortex interaction and the shear layer–vortex interaction. The former is clearly not present in the incompressible case, since there are no shocks. The shear layer–vortex interaction has been reported in the lit...

Statistics of fully turbulent impinging jets

Wilke, Robert ; Sesterhenn, Jörn (2017)

Direct numerical simulations (DNS) of subsonic and supersonic impinging jets with Reynolds numbers of 3300 and 8000 are carried out to analyse their statistical properties with respect to heat transfer. The Reynolds number range is at low or moderate values in terms of practical applications, but very high regarding the technical possibilities of DNS. A Reynolds number of 8000 is technically re...

Experimental and numerical results of active flow control on a highly loaded stator cascade

Hecklau, Martin ; Gmelin, C. ; Nitsche, W. ; Thiele, F. ; Huppertz, A. ; Swoboda, M. (2011)

This article presents experimental and numerical results for a compressor cascade with active flow control. Steady and pulsed blowing has been used to control the secondary flow and separation characteristics of a highly loaded controlled diffusion airfoil. Investigations were performed at the design incidence for blowing ratios from approximately 0.7 to 3.0 (jet-to-inlet velocity) and a Reynol...

The dynamics of volcanic jets

Cigala, V. ; Kueppers, U. ; Peña Fernández, J. J. ; Taddeucci, J. ; Sesterhenn, J. ; Dingwell, D. B. (2017-07-24)

Pyroclast ejection during explosive volcanic eruptions occurs under highly dynamic conditions involving great variations in flux, particle sizes, and velocities. This variability must be a direct consequence of complex interactions between physical and chemical parameters inside the volcanic plumbing system. The boundary conditions of such phenomena cannot be fully characterized via field obser...

Contact electrification in aerosolized monodispersed silica microspheres quantified using laser based velocimetry

Alois, Stefano ; Iversen, Jens Jacob ; Merrison, Jonathan ; Sesterhenn, Jörn (2017-04)

The contact electrification of aerosolized micro particles has been studied using a novel technique involving laser velocimetry. This has allowed the simultaneous determination of size and electrical charge of individual silica microspheres (in the range 1 – 8 µm). Interestingly the particles interacting with the injector tube have been seen to become electrified with a relatively narrow range ...

The compressible starting jet

Peña Fernández, Juan José (2018)

Jets are involved in numerous industrial applications and in nature: fuel injection, jet engines, volcanic jets, air-bag devices, but also water jet cutters, jet packs (rocket belts), jet injectors for vaccination, astrophysical jets, etc. Continuous jets have been already studied in the incompressible and compressible case for almost a century, focused mainly on the characterization of the flu...

Simulation und Analyse einer Verdichterkaskade mit aktiver Strömungsbeeinflussung

Gmelin, Christoph (2018)

Axiale Verdichter erreichen heutzutage sehr hohe Gesamtdruckverhältnisse, wozu eine hohe Anzahl von Verdichterstufen notwendig ist. Bei Flugtriebwerken stellt das Einsparen ganzer Stufen eine Möglichkeit dar, gleichzeitig das Gewicht und den Bauraum zu reduzieren. Für stationäre Gasturbinen wird der Teillastbetrieb mit steigendem Anteil an regenerativen Energien immer bedeutsamer. Beide Forderu...

Numerical simulation of a regional train in cross-wind

Eichinger, Sándor ; Sima, Mikael ; Thiele, Frank (2015)

In this work numerical investigations of regional trains were carried out studying the prediction accuracy of the aerodynamic load in cross-wind assessment of rail vehicles. The main focus is on 30° yaw angle. Two domain setups, one representing the wind tunnel setup and another more generic one, were investigated and validated against available measurements comparing load coefficients. Importa...