A. Hildebrandt | LTH - Academia.edu (original) (raw)
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Papers by A. Hildebrandt
Volume 7: Turbo Expo 2004, 2004
ABSTRACT Future pressurized Solid Oxide Fuel Cell (SOFC) Gas Turbine Hybrid Systems (HS) promise ... more ABSTRACT Future pressurized Solid Oxide Fuel Cell (SOFC) Gas Turbine Hybrid Systems (HS) promise high efficiency at both full- and part-load on account of the upper and lower SOFC temperature limit and the compressor surge line [1]. The compressor surge constraint is also evident in transient HS operation, caused by the slow transients of SOFC temperature imposed by large SOFC plenum, and fast turbo-machinery transients. This paper presents steady-state and unsteady-state HS modeling and calculation results with regard to surge. The transient compressor and SOFC models have been validated against literature. Calculation results of the coupled SOFC-GT-HS reveal a small operational window in case of unmatched turbine and the critical transient characteristics for HS shut-down.
Journal of Turbomachinery-transactions of The Asme, 2007
This paper presents a numerical investigation of the effect of different back sweep angles and ex... more This paper presents a numerical investigation of the effect of different back sweep angles and exducer widths on the steady-state impeller outlet flow pattern of a centrifugal compressor with a vaneless diffuser. The investigations have been performed with commercial computational fluid dynamics (CFD) and in-house programmed one-dimensional (1D) codes. CFD calculations aim to investigate how flow pattern from the impeller is quantitatively influenced by compressor geometry parameters; thereby, the location of wake and its magnitude (flow angle and relative velocity magnitude) are analyzed. Results show that the increased back sweep impeller provides a more uniform flow pattern in terms of velocity and flow deviation angle distribution, and offers better potential for the diffusion process inside a vaneless (or vaned) diffuser. Secondary flux fraction and flow deviation angle from CFD simulation are implemented into the 1D two-zone program to improve 1D prediction results. Downloaded 05 Nov 2008 to 130.235.253.111. Redistribution subject to ASCE license or copyright; see http://www.asme.org/terms/Terms_Use.cfm
Volume 7: Turbo Expo 2004, 2004
ABSTRACT Future pressurized Solid Oxide Fuel Cell (SOFC) Gas Turbine Hybrid Systems (HS) promise ... more ABSTRACT Future pressurized Solid Oxide Fuel Cell (SOFC) Gas Turbine Hybrid Systems (HS) promise high efficiency at both full- and part-load on account of the upper and lower SOFC temperature limit and the compressor surge line [1]. The compressor surge constraint is also evident in transient HS operation, caused by the slow transients of SOFC temperature imposed by large SOFC plenum, and fast turbo-machinery transients. This paper presents steady-state and unsteady-state HS modeling and calculation results with regard to surge. The transient compressor and SOFC models have been validated against literature. Calculation results of the coupled SOFC-GT-HS reveal a small operational window in case of unmatched turbine and the critical transient characteristics for HS shut-down.
Journal of Turbomachinery-transactions of The Asme, 2007
This paper presents a numerical investigation of the effect of different back sweep angles and ex... more This paper presents a numerical investigation of the effect of different back sweep angles and exducer widths on the steady-state impeller outlet flow pattern of a centrifugal compressor with a vaneless diffuser. The investigations have been performed with commercial computational fluid dynamics (CFD) and in-house programmed one-dimensional (1D) codes. CFD calculations aim to investigate how flow pattern from the impeller is quantitatively influenced by compressor geometry parameters; thereby, the location of wake and its magnitude (flow angle and relative velocity magnitude) are analyzed. Results show that the increased back sweep impeller provides a more uniform flow pattern in terms of velocity and flow deviation angle distribution, and offers better potential for the diffusion process inside a vaneless (or vaned) diffuser. Secondary flux fraction and flow deviation angle from CFD simulation are implemented into the 1D two-zone program to improve 1D prediction results. Downloaded 05 Nov 2008 to 130.235.253.111. Redistribution subject to ASCE license or copyright; see http://www.asme.org/terms/Terms_Use.cfm