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Dr Donato Maria Palermo


My publications

Publications

Donato M. Palermo, Feng Gao, Dario Amirante, John Chew, Anna Bru Revert, Paul Beard (2021)Computational and Experimental Assessment of Rim Sealing Flows in Axial Turbine Chute Rim Seals, In: AIAA Propulsion and Energy 2021 Forum

Hot gas ingestion in a chute seal configuration has been numerically and experimentally investigated. First, the NGVs were included to generate a swirled annulus flow. This staged approach to rig configuration is used to understand the relative contribution of rotation and NGVs induced pressure asymmetries in turbine rim sealing flow ingestion. Computations were performed with a URANS model and a novel LES code including near wall boundary layer modelling, the wall-modelled LES (WMLES). The experimental data was obtained in the Oxford Rotor Facility (ORF). The main focus of this study was the mean cavity flow aerodynamics and the sealing performance of the chute seal under a range of operating conditions. These are studied through measurements of pressure and gas concentration within the rotor-stator disc cavity and the rim seal which are compared to CFD predictions. In addition, experimental and CFD assessments of concentration-based sealing effectiveness in the gas path for the vaned configuration are presented. Measurements were taken at a representative rotor leading edge axial position to focus on the radial diffusion and interaction between the purge flow and annulus flow. Overall the WMLES code better captured the interaction between main annulus and turbine cavity flow positioning it as a powerful tool with potential to be implemented in the design and verification process.

Donato M. Palermo, Feng Gao, John W. Chew, Paul F. Beard (2019)EFFECT OF ANNULUS FLOW CONDITIONS ON TURBINE RIM SEAL INGESTION, In: Proceedings of ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition GT 2019 American Society of Mechanical Engineers (ASME)

A systematic study of sealing performance for a chute style turbine rim seal using URANS methods is reported. This extends previous studies from a configuration without external flow in the main annulus to cases with a circumferentially uniform axial flow and vane generated swirling annulus flow (but without rotor blades). The study includes variation of the mean seal-to-rotor velocity ratio, main annulus-to-rotor velocity ratio, and seal clearance. The effects on the unsteady flow structures and the degree of main annulus flow ingestion into the rim seal cavity are examined. Sealing effectiveness is quantified by modeling a passive scalar, and the timescales for the convergence of this solution are considered. It has been found that intrinsic flow unsteadiness occurs in most cases, with the presence of vanes and external flow modifying, the associated flow structures and frequencies. Some sensitivities to the annulus flow conditions are identified. The circumferential pressure asymmetry generated by the vanes has a clear influence on the flow structure but does not lead to higher ingestion rates than the other conditions studied.

Donato M. Palermo, Feng Gao, Dario Amirante, John W. Chew, Anna Bru Revert, Paul F. Beard (2020)WALL-MODELLED LARGE EDDY SIMULATIONS OF AXIAL TURBINE RIM SEALING, In: ASME Turbomachinery Technical Conference & Exposition 2020

This paper presents WMLES simulations of a chute type turbine rim seal. Configurations with an axisymmetric annulus flow and with nozzle guide vanes fitted (but without rotor blades) are considered. The passive scalar concentration solution and WMLES are validated against available data in the literature for uniform convection and a rotor-stator cavity flow. The WMLES approach is shown to be effective, giving significant improvements over an eddy viscosity turbulence model, in prediction of rim seal effectiveness compared to research rig measurements. WMLES requires considerably less computational time than wall-resolved LES, and has the potential for extension to engine conditions. All WMLES solutions show rotating inertial waves in the chute seal. Good agreement between WMLES and measurements for sealing effectiveness in the configuration without vanes is found. For cases with vanes fitted the WMLES simulation shows less ingestion than the measurements, and possible reasons are discussed.

John Chew, Feng Gao, Donato Maria Palermo (2018)Flow mechanisms in axial turbine rim sealing, In: Proc. IMechE part C: Journal of Mechanical Engineering Science SAGE Publications Ltd

This paper presents a review of research on turbine rim sealing with emphasis placed on the underlying flow physics and modelling capability. Rim seal flows play a crucial role in controlling engine disc temperatures but represent a loss from the main engine power cycle and are associated with spoiling losses in the turbine. Elementary models that rely on empirical validation and are currently used in design do not account for some of the known flow mechanisms, and prediction of sealing performance with computational fluid dynamics (CFD) has proved challenging. CFD and experimental studies have indicated important unsteady flow effects that explain some of the differences identified in comparing predicted and measure sealing effectiveness. This review reveals some consistency of investigations across a range of configurations, with inertial waves in the rotating flow apparently interacting with other flow mechanisms which include vane, blade and seal flow interactions, disc pumping and cavity flows, shear layer and other instabilities, and turbulent mixing.

Donato M. Palermo, Feng Gao, Dario Amirante, John Chew, Anna Bru Revert, Paul F. Beard (2020)Wall Modelled Large Eddy Simulations of Axial Turbine Rim Sealing, In: Journal of Engineering for Gas Turbines and Power American Society of Mechanical Engineers (ASME)

This paper presents WMLES simulations of a chute type turbine rim seal. Configurations with an axisymmetric annulus flow and with nozzle guide vanes fitted (but without rotor blades) are considered. The passive scalar concentration solution and WMLES are validated against available data in the literature for uniform convection and a rotor-stator cavity flow. The WMLES approach is shown to be effective, giving significant improvements over an eddy viscosity turbulence model, in prediction of rim seal effectiveness compared to research rig measurements. WMLES requires considerably less computational time than wall-resolved LES, and has the potential for extension to engine conditions. All WMLES solutions show rotating inertial waves in the chute seal. Good agreement between WMLES and measurements for sealing effectiveness in the configuration without vanes is found. For cases with vanes fitted the WMLES simulation shows less ingestion than the measurements, and possible reasons are discussed.