SFB 1029 - TurbIn

19 Items

Recent Submissions
Numerical Assessment of Virtual Control Surfaces for Load Alleviation on Compressor Blades

Motta, Valentina ; Malzacher, Leonie ; Peitsch, Dieter (2018-01-17)

Virtual control surfaces for the optimization of steady and unsteady airloads on a compressor cascade are assessed numerically. The effects of mechanical surfaces are realized with plasma actuators, located both on the pressure and on the suction side of the blade trailing edge. Suction side plasma actuation is thought to reproduce the effects of mechanical wing spoilers, whereas pressure side ...

Entwicklung von Fehlererkennungs-, Zustandsschätzungs-, Regelungs- und ganzzahligen Optimalsteuerungsmethoden für pulsierende, detonative Brennkammern anhand eines akustischen Ersatzsystems

Wolff, Sascha Dominik (2019)

Aktuelle Forschungsbestrebungen zur Effizienzsteigerung von Gasturbinen verfolgen häufig den Ansatz eines Wechsels des zugrundeliegenden Kreisprozesses weg vom Brayton- hin zum Humphrey-Kreisprozess. Eine vielversprechende Möglichkeit, diesen Kreisprozess technischzu realisieren, ist durch den Einsatz einer pulsierenden, druckerhöhenden Detonationsbrennkammer gegeben. Eine solche Brennkammer be...

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...

Geregelte Strömungskontrolle einer Statorkaskade mit Seitenwand- und Hinterkantenaktuation

Kiesner, Matthias (2018)

Die Steigerung des Wirkungsgrades von Gasturbinen ist ein wichtiges Entwicklungs- und Forschungsziel. Durch die große Stückzahl der weltweit im Energie- und Transportsektor eingesetzten Gasturbinen ist das Potential für eine Reduktion der Treibhausgasemissionen enorm. Aktuell wird eine neue Technologie erforscht, die einen Wechsel von der konventionellen isobaren Verbrennung zu einer isochoren ...

Wissenschaftskulturen im Dialog – Wissenschaftsrezeption und Wissenschaftsmoderation im Zeitalter global verfügbarer Online-Publikationen

Otto, Gabriele E. (2018)

Diese Arbeit wendet sich Fragen nach den Bedingungen für eine pluri-kulturelle Nutzung wissenschaftlichen Wissens im Internet zu. Ausgehend von kulturellen Prägungen der Wissenschafts- und akademischen Kulturen in Indonesien und in Deutschland aus der Sicht der DaF-Didaktik und der Anthropologie werden anhand von exemplarischen Untersuchungen an Bachelor-Arbeiten zur Literaturwissenschaft aus I...

Data-driven interpolation of dynamical systems with delay

Schulze, Philipp ; Unger, Benjamin (2015)

We present a data-driven realization for systems with delay, which generalizes the Loewner framework. The realization is obtained with low computational cost directly from measured data of the transfer function. The internal delay is estimated by solving a least-square optimization over some sample data. Our approach is validated by several examples, which indicate the need for preserving the d...

A Matlab toolbox for the regularization of descriptor systems arising from generalized realization procedures

Binder, Amelie ; Mehrmann, Volker ; Miedlar, Agnieszka ; Schulze, Philipp (2015)

In this report we introduce a Matlab toolbox for the regularization of descriptor systems. We apply it, in particular, for systems resulting from the generalized realization procedure of [16], which generates, via rational interpolation techniques, a linear descriptor system from interpolation data. The resulting system needs to be regularized to make it feasible for the use in simulation, opti...

The shifted proper orthogonal decomposition

Reiss, Julius ; Schulze, Philipp ; Sesterhenn, Jörn (2015)

Transport-dominated phenomena provide a challenge for common mode-based model reduction approaches. We present a model reduction method, which extends the proper orthogonal decomposition (POD) by introducing time-dependent shifts of the snapshot matrix. The approach, called shifted proper orthogonal decomposition (sPOD), features a determination of the multiple transport velocities and a separa...

Port-Hamiltonian realizations of linear time invariant systems

Beattie, Christopher ; Mehrmann, Volker ; Xu, Hongguo (2015)

The question when a general linear time invariant control system is equivalent to a port-Hamiltonian systems is answered. Several equivalent characterizations are derived which extend the characterizations of [38] to the general non-minimal case. An explicit construction of the transformation matrices is presented. The methods are applied in the stability analysis of disc brake squeal.

On the port-Hamiltonian structure of the Navier-Stokes equations for reactive flows

Altmann, Robert ; Schulze, Philipp (2016)

We consider the problem of finding an energy-based formulation of the Navier-Stokes equations for reactive flows. These equations occur in various applications, e. g., in combustion engines or chemical reactors. After modeling, discretization, and model reduction, important system properties as the energy conservation are usually lost which may lead to unphysical simulation results. In this pa...

Numerical solution of singularly perturbed convection-diffusion-reaction problems with two small parameters

Das, Pratibhamoy ; Mehrmann, Volker (2015)

This paper discusses the numerical solution of 1-D convection-diffusion-reaction problems that are singularly perturbed with two small parameters using a new mesh-adaptive upwind scheme that adapts to the boundary layers. The meshes are generated by the equidistribution of a special positive monitor function. Uniform, parameter independent convergence is shown and holds even in the limit that ...

Shockless explosion combustion

Bobusch, Bernhard C. ; Berndt, Phillip ; Paschereit, Christian Oliver ; Klein, Rupert (2014-09-30)

Constant volume combustion (CVC) in gas turbines is a promising way to achieve a step change in the efficiency of such systems. The most widely investigated technique to implement CVC in gas turbine systems is pulsed detonation combustion (PDC). Unfortunately, the PDC is associated with several disadvantages, such as sharp pressure transitions, entropy generation due to shock waves, and exergy ...

Investigation of Fluidic Devices for Mixing Enhancement for the Shockless Explosion Combustion Process

Bobusch, Bernhard ; Berndt, Phillip ; Paschereit, Christian Oliver ; Klein, Rupert (2014-09)

Fuel-air mixing is a crucial process in low emission combustion systems. A higher mixing quality leads to lower emissions and higher combustion efficiencies. Especially for the innovative constant volume combustion processes "Shockless Explosion Combustion" (SEC) the mixing of fuel and air is an important parameter, since the whole combustion process is triggered and controlled via the equivale...

Experimental investigation of a turbine sealing cavity exposed to free stream pressure fluctuation

Schliwka, Tobias ; Malzacher, Leonie ; Chemnitz, Silvio ; Peitsch, Dieter (2014-09-10)

The current investigation examines the impact of a new pulsed unsteady combustion to the turbine sealing cavity, which prevents hot gas ingestion into the inner machine. Sealing flow is ensured by relatively cold secondary air blowing radially through the rotor-stator-wheel space. The interaction between the sealing flow and the main gas flow however causes aerodynamic losses. These losses as w...

Active Flow Control by Adaptive Blade Systems in Periodic Unsteady Flow Conditions

Hammer, Steffen ; Phan, Dat Tien ; Peter, Julija ; Werder, Tobias ; Meyer, Robert ; Liebich, Robert ; Thamsen, Paul Uwe (2014-09-10)

A test stand to investigate the rotor-stator interaction of a compressor stage is presented. This water channel allows to investigate the influence of wake depressions and choking to a stator cascade. Furthermore, adaptive blade systems are presented to affect the operating of stator under periodic unsteady flow conditions. The piezoelectric actuators are one of these adaptive blade systems. Th...

Experimental Investigation of a 7 by 7 Nozzle Jet Array for Dynamic Impingement Cooling

Haucke, Frank ; Kroll, Henning ; Peltzer, Inken ; Nitsche, Wolfgang (2014-09-10)

Dynamic impingement cooling is a promising way for more efficient exploitation of cooling air in highly heat charged environments. In many applications the deployed impinging jets are subjected to crossflow superimposed on the flow field of the transverse jets. The present study describes the initial experimental investigations regarding dynamic heat transfer between a flat surface and an array...

Review: Active Control of Shock-associated Unsteady Flow Phenomena in Aeroengines - Suppression Techniques for Transonic Cascade Flutter and Supersonic Jet Noise -

Watanabe, Toshinori (2014-09-10)

Active control techniques for cascade flutter suppression and supersonic jet noise reduction were studied in the University of Tokyo. For flutter suppression, piezoelectric devices were installed on the blade surfaces. The active oscillation of the trailing edge of a blade was found to suppress the flutter instability in the numerical analysis. The effect was qualitatively confirmed in a trial ...

Internal Flow Physics of a Fluidic Oscillator in the Transition Regime

Gregory, James W. ; Tomac, Mehmet N. (2014-09)

An experimental investigation of the underlying flow physics of a dual jet interaction fluidic oscillator has been conducted in the transition regime for a Reynolds number of 1680. The transition regime is defined as a narrow range of flow rates between two other operating modes of the fluidic oscillator. Particle image velocimetry (PIV) was used with refractive index matching sodium iodide sol...