Numerical and experimental evaluation of the time-variant flow field in a single-blade centrifugal pump

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.In this contribution the time-variant flow in a single-blade pump is evaluated by numerical and experimental methods. In a numerical approach the three-dimensional, viscous, unsteady flow field in the complete pump has been achieved by solving the unsteady Navier-Stokes equations (URANS) with different commercial solvers in a wide range of pump operation. From the calculated periodic flow field the hydrodynamic forces resulting from the time-variant pressure field and viscous stresses were determined for a complete impeller revolution. To validate the results of the numerical simulations a test rig was used to conduct some measurements in the pump. First of all the velocity field inside the pump was investigated by using the Particle Image Velocimetry. A good agreement between the velocity fields obtained by numerical simulations and by measurements has been achieved. In a second step the transient hydrodynamic forces of the pump were measured by acquisition of the appropriate forces acting on the bearings of the pump rotor during operation. The measurements of the hydrodynamic forces match the results of the numerical simulations very well. In particular, the good qualitative agreement suggests that predicting the transient flow in (single-blade) centrifugal pumps utilizing a Navier-Stokes (URANS) solver, is a reliable method to determine the time-variant hydrodynamic forces, which are decisive for the vibrations of the pump.cs201

Efficiency augmentation of gas turbine cycles

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.The efficiency of gas turbine cycles can be enhanced by application of several methods. In the present contribution, the four most promising options e.g. compressor cooling, recuperation, reheating and elevation of turbine inlet temperature are discussed in detail. The potential of efficiency augmentation is depicted for all described methods with respect to the required effort. In addition, it is shown that the combination of different cycle improvement methods can give a disproportional high benefit because of upcoming synergy effects. For the compressor cooling it is worked out that an unconventional cooling by water injection gives a superior result over a conventional cooling. Furthermore, as any cooling of the compression process is accompanied with lower compressor outlet temperatures a strong potential for recuperation is provided by combining both methods. Finally, the obtainable efficiency of a gas turbine is determined for combination of several enhancement methods.pm201

Water droplet evaporation at high pressure and temperature levels - Part i: Experimental investigations of spray patterns at varied test conditions

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.Water injection into gas turbines is subject of investigations since decades, due to a high power and efficiency augmentation potential compared to the simple gas turbine cycle. Based on former research at ambient conditions, some technologies have already been realized, e.g. inlet fogging. Further applications of water injection at higher temperature and pressure levels are limited, because of few experimental data. In order to gain fundamental understanding at these boundary conditions, a novel test facility for droplet evaporation investigations has been built up at the University of Duisburg-Essen. The resulting spray patterns are recorded by a laser based measuring technology, Phase Doppler Particle Analyzer (PDPA). Part I of the paper treats the experimental setup of the test facility; in particular the laser based measuring technology, as well as the measurement results of the spray pattern produced from a nozzle at high pressure and temperature levels. The focus of the investigations is on the droplet evaporation process in dependence on parameter variation of the environmental conditions.dc201

Water droplet evaporation at high pressure and temperature levels – part II: comparison of experimental results with a 1D simulation

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.Water injection into gas turbines is subject of investigations since decades, due to a high power and efficiency augmentation potential compared to the simple gas turbine cycle. Based on former research at ambient conditions, some technologies have already been realized, e.g. inlet fogging. Further applications of water injection at higher temperature and pressure levels are limited, because of few experimental data. In order to gain fundamental understanding at these boundary conditions, a novel test facility for droplet evaporation investigations has been built up at the Department of Mechanical Engineering at University of Duisburg-Essen. The resulting spray patterns are recorded by a laser based measuring technology, Phase Doppler Particle Analyzer (PDPA). In this second part of the paper, experimental results from the test facility are compared to simulation results of a 1D- model for droplet evaporation. The focus of this investigation is on the accordance of the simulation results with the experimental data at high pressure and temperature levels.dc201

Beitrag zur Berechnung der Stroemung in mehrstufigen Axialverdichtern unter besonderer Beruecksichtigung der Seitenwandgrenzschichten und der Sekundaerstroemungen

TIB: DP 9259 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman