Session: 35-18 Turbine Methods 2
Paper Number: 102206
102206 - Numerical Study on the Influence of Geometrical Parameters on the Performance of a Turbine Exhaust Hood.
Complying with current environmental requirements, modern turbine designs must be robust, highly efficient, and able to operate at flexible operating conditions simultaneously.
Leaving the last turbine stage, the remaining kinetic flow energy is converted into static pressure in the turbine exhaust hood. An improvement of the pressure recovery in this component and especially in its diffuser can increase the overall turbine performance.
In a current study, an axial-radial diffuser is investigated, which represents a typical compact design for industrial turbine exhaust hoods. Since this diffuser exhaust-hood system turns the flow direction from axial to radial direction over a short distance, a characteristic complex three-dimensional asymmetric and unsteady flow field results. Due to this flow topology, local flow separations occur in regions with stronger adverse pressure gradients limiting the maximum overall pressure recovery of the exhaust hood.
This paper presents the influence of geometrical diffuser parameters on the diffuser exhaust-hood system performance in terms of pressure recovery, pressure loss, and flow-field asymmetry based on numerical flow simulations. For this purpose, a Design of Experiment (DoE) analysis is performed on a parametrised model of a diffuser exhaust-hood system for a newly developed diffuser test rig. The diffuser geometry is parameterised and a sensitivity study of the geometrical parameters with respect to the pressure recovery and pressure loss is performed for two operating conditions. Thus, the aerodynamic influence of the diffuser outlet area and its interactions with the exhaust hood is studied, whereby the diffuser geometry is modified asymmetrically in accordance with the asymmetric flow topology.
The simulation results indicate that the overall pressure recovery as well as the pressure loss of the diffuser exhaust-hood system can be influenced through asymmetric diffuser-shape modifications. Besides, it is demonstrated, that the aerodynamic origins of these sensitivities emerge from the local diffuser-loading and flow distribution.
Presenting Author: Anastasia Fomina ITSM, University of Stuttgart
Presenting Author Biography: I am a research engineer at the Institute of Thermal Turbomachinery and Machinery Laboratory at the University of Stuttgart, Germany, since November 2020. I studied at Karlsruhe Institute of Technology from October 2014 to October 2020 and graduated with the master degree in process engineering with spezialization in energy technology and thermodynamics.
Authors:
Anastasia Fomina ITSM, University of StuttgartChristopher Fuhrer ITSM, University of Stuttgart
Damian M. Vogt ITSM, University of Stuttgart
Tobias Willeke MAN Energy Solutions SE
Numerical Study on the Influence of Geometrical Parameters on the Performance of a Turbine Exhaust Hood.
Paper Type
Technical Paper Publication