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Numerical Noise Prediction in Fluid Machinery

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Journal of Thermal Science 2005年第3期14卷 230-235,248页

作者： Iris PANTLE Franco MAGAGNATO martin gabi Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe

Numerical methods successively became important in the design and optimization of fluid machinery. However, as noise emission is considered, one can hardly find standardized prediction methods combining flow and acoustical optimization. Several numerical field methods for sound calculations have been developed. Due to the complexity of the considered flow, approaches must be chosen to avoid exhaustive computing. In this contribution the noise of a simple propeller is investigated. The configurations of the calculations comply with an existing experimental setup chosen for evaluation. The used in-house CFD solver SPARC contains an acoustic module based on Ffowcs Williams-Hawkings Acoustic Analogy. From the flow results of the time dependent Large Eddy Simulation the time dependent acoustic sources are extracted and given to the acoustic module where relevant sound pressure levels are calculated. The difficulties, which arise while proceeding from open to closed rotors and from gas to liquid are discussed.

关键词： numerical noise prediction fluid machinery computational aero-acoustics large eddy simulation

Empirical Model for the Quantitative Prediction of Losses of Radial Fans based on CFD Calculations

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Journal of Thermal Science 2013年第4期22卷 304-310页

作者： Heiko Ratter Saban Caglar martin gabi Institute of Fluid Machinery Karlsruhe Institute of Technology Kaiserstrasse 1276131 Karlsruhe Germany

In a classical layout process of a fan the quantity of losses is estimated as a sum and expressed in the overall efficiency rote However the characteristic of the pressure rise, the losses and the efficiency rate beside the design point is not known. Against this background a numerical model was developed to calculate quantitative values of occurring losses at radial fan impellers at an early stage in the design process. It allows to estimate the pressure rise and efficiency rate of a given fan geometry at and beside the design point. The physics of losses are described in literature, but obtaining quantitative values is still a challenge. As common in hydraulic theory the losses are calculated with analytic formulas supported by coefficients and efficiency rates, which have to be determined empirically. This paper shows the method how to determine the coefficients for a given radial fan. Therefore a representative radial fan with backward curved blades was designed in reference to classical design guidelines. Performance measuring was done conform to ISO 5801. The flow was calculated at 8 different operation points using CFD methods. The RANS equations are solved by using the SST-k-omega turbulence model. The flow do- main consists of one blade section including inlet channel and outflow chamber. Spatial discretization is done by a block-structured mesh of approx. 1.8 million cells. Performance data show a very good agreement between measurement and calculation.

关键词： loss model radial fan CFD RANS

Flow Field and Performance of Cross Flow Fans——Experimental and Theoretical Investigations

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Journal of Thermal Science 2003年第3期12卷 234-238页

作者： martin gabi Simon Dornstetter Toni Klemm Institute of Fluid Machinery University of Karlsruhe (TH) D-76128 Karlsruhe GermanyRobert Bosch GmbH D-71701 Schwieberdingen GermanyInstitute of Fluid Machinery University of Karlsruhe (TH) D-76128 Karlsruhe Germany

Due to the construction and the operating principle the prediction of performance of Cross Flow Fans (CFF) is difficult and the knowledge about the internal flow regime is limited. To investigate the impact of geometrical parameters on the performance of CFF, experimental investigations, using Particle Imaging Velocimetry (PIV), and CFD calculations were carried out. Some results of PIV measurements and CFD calculations are presented, which give an impression of the internal flow and confirm the numerical calculations.

关键词： fans cross-flow fans computational fluid dynamics particle imaging velocimetry

Investigations on the Flow Field in an Unshrouded Pump Impeller Geometry

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Journal of Thermal Science 2012年第2期21卷 136-144页

作者： Sten Sieber Friedrich Frhlig Saban Caglar martin gabi Fchgebiet Strmungsmaschinen Karlsruhe Institute of Technology Germany

Transient CFD simulations are performed to investigate the flow behaviour inside an unshrouded pump using the SAS method. Two blade designs are compared at two different tip clearances and the results are validated by measurements. The detected vortex structure is visualized by the normalized helicity, further discussed regarding its development and behaviour and finally implicated to the efficiency of the two different blade designs.

关键词： unshrouded pump tip clearance helicity

Prediction of the Resonance Characteristics of Combustion Chambers on the Basis of Large-Eddy Simulation

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Journal of Thermal Science 2005年第2期14卷 156-161页

作者： Franco MAGAGNATO Balázs PRITZ Horst BCHNER martin gabi Department of Fluid Machinery University of Karlsruhe GermanyDepartment of Fluid Machinery University of KarlsruheGermanyEngler-Bunte-Institute/Division for Combustion Technology University of KarlsruheGermanyDepartment of Fluid Machinery University of KarlsruheGermany

In the last few years intensive experimental investigations were performed at the University of Karlsruhe to develop an analytical model for the Helmholtz resonator-type combustion system. In the present work the resonance characteristics of a Helmholtz resonator-type combustion chamber were investigated using large-eddy simulations (LES), to understand better the flow effects in the chamber and to localize the dissipation. In this paper the results of the LES are presented, which show good agreement with the experiments. The comparison of the LES study with the experiments sheds light on the significant role of the wall roughness in the exhaust gas pipe.

关键词： compressible large-eddy simulation combustion instabilities oscillating flow damping ratio.

Numerical Investigation of Effective Heat Conductivity of Fluid in Charging Process of Thermal Storage Tank

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Open Journal of Fluid Dynamics 2015年第1期5卷 39-50页

作者： Hadi Taheri Ferdinand P. Schmidt martin gabi Institute of Fluid Machinery Department of Mechanical Engineering Karlsruhe Institute of Technology Karlsruhe Germany

This paper presents a numerical case study of heat transfer mechanisms during the charging process of a stratified thermal storage tank applied in a specific adsorption heat pump cycle. The effective thermal conductivity of the heat transfer fluid during the charging process is analyzed through CFD simulations using Unsteady Reynolds-averaged Navier-Stokes equations (URANS). The aim of the study is to provide an equivalent thermal conductivity for a one-dimensional storage tank model to be used in a system simulation of the complete adsorption heat pump cycle. The influence of the turbulent mixing and also the advection effect due to fluid bulk motion are investigated. The results show that in the case considered here, the turbulence effect on the effective thermal conductivity is more considerable than the advection effect.

关键词： Thermal Storage Tank Stratification Pipe Effective Thermal Conductivity