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Institute of Turbomachinery and Fluid Dynamics
Logo Leibniz Universität Hannover
Institute of Turbomachinery and Fluid Dynamics
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Working Group Turbochargers and Centrifugal Compressors

Description

Centrifugal machines are key components that help to further increase fuel efficiency in next-generation vehicles; they are also an important component of future energy supply systems. The current trend of downsizing also applies to the size of combustion engines. Utilizing increased turbocharging an equal power level can be achieved with lower fuel consumption. The resulting higher boost pressures and exhaust gas temperatures, as well as the demand for a wider operation range are the current challenges in turbocharger design. In addition, centrifugal compressors are used to deliver natural gas in pipelines or as air supply system for fuel cells. In the future these centrifugal compressors will increasingly operate in the partial load range to maintain a constant pipeline pressure, compensating for the fluctuations in the pipeline network. Fuel cell systems for household and vehicle energy supplies have to be dynamically controlled in accordance with fluctuating demand.

Improving the part load performance of centrifugal compressors is an important area of research at TFD. To this end, the physical flow phenomena at the operating limits are investigated using numerical and experimental methods. The results are used for the further development of static components, such as inlet guide vanes, bladed diffuser or asymmetric spiral, as well as for the development of the compressor’s rotor with the overall goal to extend the operating range of the compressor and to improve the efficiency. Another focus is on improving the part load behavior of small turbocharger turbines. In addition to the further development of classical control mechanisms, the concept of turbine impellers is the subject of current research. Consideration of diabatic  effects in turbocharger analysis is an important field of research at the TFD, as turbocharger performance is strongly influenced by heat loss and heat transfer inside the turbocharger.

Another field of work covered by this group is the design of compact turbomachinery and the further improvement of existing design processes at TFD for this machine class. This work includes the development of process chains and derivation of appropriate design criteria. For the development of new design tools, simulation and optimization strategies are developed to reduce development times and save resources. The turbomachines are then produced as prototypes and tested experimentally.

Completed Projects in the Turbocharger Area

  • Turbochargers with shrouds to reduce turbine clearance losses
  • Blow-by in turbochargers
  • Secondary flows in turbine turbochargers with variable turbine geometry
  • Application of the infinite tube technique for measuring the unsteady pressure in the turbocharger radial turbines
  • Influence analysis of the arrangement and operation on surge of turbochargers
  • Experimental investigation and simulation of advanced non-adiabatic performance of the turbochargers

Completed Projects in the Centrifugal Compressor Area

  • Development of Endoscopic Stereoscopic PIV to investigate the IGV-impeller Interaction in a Centrifugal Compressor
  • Experimental Studies on the Improvement Potential of a Centrifugal Compressor Stage with Different Spiral Geometries

Current Projects

  • Design and Optimization of Dynamic Compressors
  • Design of an Impulse Turbine for an ORC Process to use the Waste Heat from Truck Engines
  • Design of Turbocharger Turbines with Regards to Pulsating Exhaust Mass Flows
  • Impact Analysis of Dissipation in the Lubrication Film of Turbochargers
  • Investigation of Surge in Turbocharger Compressors and Design of Map-Extending Measures
  • Variable Diffuser and Volute for Air Supply to Fuel Cell Systems

Contacts

Group Leader

Dipl.-Ing. Ole Willers

Assistant Group Leader

Dipl.-Ing. Henning Rätz