The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform

I. L. Maikov - One of the best experts on this subject based on the ideXlab platform.

  • Simulation of hydrodynamics and burning in cylindrical Combustion Chambers
    Thermal Engineering, 1998
    Co-Authors: G. S. Aslanyan, I. L. Maikov
    Abstract:

    A numerical model for calculating flows in three-dimensional Combustion Chambers using cylindrical coordinates is developed. A hydrodynamics model is constructed on the basis of the algorithm SIMPLE, in which the Navier-Stokes equations in natural variables U, V, W, and P are solved. Turbulence is considered within the scope of the k-e model. The approximation of local thermodynamic equilibrium is employed with a flow-mixing function, and its dispersion is introduced, as well as a probability density function of the rectangular type for obtaining mean values. Satisfactory agreement with calculations and experiments that were made is shown.

  • Simulation of turbulent flow in three-dimensional Combustion Chambers
    Thermal Engineering, 1996
    Co-Authors: G. S. Aslanyan, I. L. Maikov
    Abstract:

    A numerical model for calculating flows in three-dimensional Combustion Chambers is presented. The algorithm SIMPLE for the physical variables U, V, W, and p is used in the numerical solution of the Navier-Stokes equations. Turbulence is considered within the framework of the k-e model that is extended to include three-dimensional geometry using wall functions at solid boundaries. In solving the difference equations, the two-dimensional sweep method, extrapolated to cover the three-dimensional case, is used.

Oskar Haidn - One of the best experts on this subject based on the ideXlab platform.

  • experimental investigations of thermomechanical fluid structure interaction in rocket Combustion Chambers
    Journal of Propulsion and Power, 2019
    Co-Authors: Felix Hötte, Torben Fiedler, Matthias Haupt, Paul Lungu, Christoph Von Sethe, Oskar Haidn
    Abstract:

    This paper aims at investigations of thermomechanical fluid–structure interaction in regeneratively cooled rocket Combustion Chambers. In the first part the setup of a thermal cyclic fatigue experi...

  • Experimental Investigations of Thermomechanical Fluid–Structure Interaction in Rocket Combustion Chambers
    Journal of Propulsion and Power, 2019
    Co-Authors: Felix Hötte, Torben Fiedler, Matthias Haupt, Paul Lungu, Christoph Von Sethe, Oskar Haidn
    Abstract:

    This paper aims at investigations of thermomechanical fluid–structure interaction in regeneratively cooled rocket Combustion Chambers. In the first part the setup of a thermal cyclic fatigue experi...

  • CFD Analyses of Effusion Cooled Combustion Chambers
    2005
    Co-Authors: Jörg Riccius, Oskar Haidn, Tobias Leicht
    Abstract:

    In order to increase the efficiency of currently available 10 MPa Combustion Chambers, hot gaspressures of up to 25 MPa are desirable. As such high pressures lead to an increased heat transferfrom the hot gas into the Combustion chamber wall, alternative cooling methods to the conventional regenerative cooling are required. One of the most promising alternative cooling approach is effusion cooling. The advantages of effusion cooling are damage tolerance and a comparatively low weight. Since a few years DLR works on the field of effusion technology [1,2]. In the current paper, underlying CFD analyses are shown. These CFD analyses are based of the following principles: - rotatory symmetric model - solution of the Navier Stokes equations - coupled analysis of the hot gas and the coolant flow („multi species“) - compressible solution algorithm - ideal gas equation - k-e turbulence model in the Combustion chamber - no turbulence model in the chamber wall - „distributed resistance“ according to Forchheimer in the chamber wall

  • Fabrication of TBC-armored rocket Combustion Chambers by EB-PVD methods and TLP assembling
    Science and Technology of Advanced Materials, 2005
    Co-Authors: Uwe Schulz, Klaus Fritscher, Manfred Peters, Dirk Greuel, Oskar Haidn
    Abstract:

    A thermal barrier coating (TBC) system for rocket Chambers made of Cu-based high strength alloys has been developed in a pilot project in line with EB-PVD (electron-beam physical vapor deposition) technology aiming at TBC application on Cu-based walls of real rocket Combustion Chambers. The TBC system consists of a metallic bond coating compatible with Cu-based material and an yttria partially stabilized zirconia TBC. The TBC overlayer is a distinctive ceramic structure designed for an exceptionally low Young's modulus to withstand the extreme mismatch stresses between the internally LN-cooled high thermal expansion Cu metal base and the low thermal expansion hot ceramic shell. The TBC system has been qualified under close-to-service conditions on cylindrical LH2-cooled Combustion chamber segments, where they have performed superior.As EB-PVD technology is a line-of-sight process that is rather able to coat internal cavities, a transient liquid phase (TLP) joining technique for fully coated parts has been developed, that allows to assemble complete components out of vapor-accessible fully coated parts. It is capable, e.g. to incorporate sinuous cooling passages in the throat areas of Combustion Chambers, and/or to assemble oversized parts out of smaller components by maintaining parent metal properties. A manufacturing process is outlined for making internal TBC armored Combustion Chambers.

G. S. Aslanyan - One of the best experts on this subject based on the ideXlab platform.

  • Simulation of hydrodynamics and burning in cylindrical Combustion Chambers
    Thermal Engineering, 1998
    Co-Authors: G. S. Aslanyan, I. L. Maikov
    Abstract:

    A numerical model for calculating flows in three-dimensional Combustion Chambers using cylindrical coordinates is developed. A hydrodynamics model is constructed on the basis of the algorithm SIMPLE, in which the Navier-Stokes equations in natural variables U, V, W, and P are solved. Turbulence is considered within the scope of the k-e model. The approximation of local thermodynamic equilibrium is employed with a flow-mixing function, and its dispersion is introduced, as well as a probability density function of the rectangular type for obtaining mean values. Satisfactory agreement with calculations and experiments that were made is shown.

  • Simulation of turbulent flow in three-dimensional Combustion Chambers
    Thermal Engineering, 1996
    Co-Authors: G. S. Aslanyan, I. L. Maikov
    Abstract:

    A numerical model for calculating flows in three-dimensional Combustion Chambers is presented. The algorithm SIMPLE for the physical variables U, V, W, and p is used in the numerical solution of the Navier-Stokes equations. Turbulence is considered within the framework of the k-e model that is extended to include three-dimensional geometry using wall functions at solid boundaries. In solving the difference equations, the two-dimensional sweep method, extrapolated to cover the three-dimensional case, is used.

Thierry Poinsot - One of the best experts on this subject based on the ideXlab platform.

  • A simple analytical model to study and control azimuthal instabilities in annular Combustion Chambers
    Combustion and Flame, 2012
    Co-Authors: Jean-françois Parmentier, Pablo Salas, Gabriel Staffelbach, Pierre Wolf, Franck Nicoud, Thierry Poinsot
    Abstract:

    This study describes a simple analytical method to compute the azimuthal modes appearing in annular Combustion Chambers and help analyzing experimental, acoustic and LES (Large Eddy Simulation) data obtained in these Combustion Chambers. It is based on a one-dimensional zero Mach number formulation where N burners are connected to a single annular chamber. A manipulation of the corresponding acoustic equations in this configuration leads to a simple dispersion relation which can be solved by hand when the interaction indices of the flame transfer function are small and numerically when they are not. This simple tool is applied to multiple cases: (1) a single burner connected to an annular chamber (N = 1), (2) two burners connected to the chamber (N = 2), (3) four burners (N = 4). In this case, the tool also allows to study passive control methods where two different types of burners are mixed to control the azimuthal mode. Finally, a complete helicopter chamber (N = 15) is studied. For all cases, the analytical results are compared to the predictions of a full three-dimensional Helmholtz solver and a very good agreement is found. These results show that building very simple analytical tools to study azimuthal modes in annular Chambers is an interesting path to control them.

  • Stability of azimuthal modes in annular Combustion Chambers
    2011
    Co-Authors: Pablo Salas, Luc Giraud, Jens-dominik Müller, Gabriel Staffelbach, Thierry Poinsot
    Abstract:

    Thermoacoustic instabilities are an important concern in the design of gas turbine Combustion Chambers. Most modern Combustion Chambers have annular shapes and this leads to the appearance of azimuthal acoustic modes. These modes are often powerful and can lead to structural vibrations being sometimes damaging. Therefore, they must be identified at the design stage in order to be able to eliminate them. However, due to the complexity of industrial Combustion Chambers with a large number of burners, numerical studies of real configurations are a challenging task. The following work shows results obtained on an industrial annular gas turbine combustor with 24 burners using an acoustic approach. Assuming that each burner does not interact with the adjacent ones and is influenced only by the fluctuations of the flow rate through it, the Flame Transfer Function (FTF) of a single burner can be calculated via a single burner LES and used to simulate the acoustics of the 360° geometry (24 burners). This approach allows to predict stability changes when the flame is modified and to propose combustor modifications increasing the stability of the engine.

Clas A. Jacobson - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive stabilization of nonlinear acoustic oscillations in Combustion Chambers
    Proceedings of the 36th IEEE Conference on Decision and Control, 1
    Co-Authors: Miroslav Krstic, A. Krupadanam, Clas A. Jacobson
    Abstract:

    We present a self-tuning scheme for adapting the parameters of a PI controller proposed by Fung-Yang (1992) for stabilization of a Culick-type model of nonlinear acoustic oscillations in Combustion Chambers. Our adaptation criterion is Lyapunov-based. We focus on a two-mode model and develop a design based on an assumption that the amplitudes of the two modes are available for measurement. The adaptation mechanism is designed to stabilize both modes and prevent the phenomenon observed by Billoud et al. (1992) whose adaptive controller stabilizes the first but destabilizes the second mode. We also prove that the adaptation mechanism is robust to a time delay inherent to the actuation approach via heat release. We also develop an adaptation scheme which employs only one pressure sensor. Our approach is based on the idea to use the squares of the pressure and its derivative. Simulations illustrate the capability of the scheme to attenuate limit cycles without the knowledge of the growth coefficients.