Dario Amirante

Dario Amirante


Research Fellow
+44 (0)1483 682333
05A AB 01

Academic and research departments

Department of Mechanical Engineering Sciences.

My publications

Publications

Amirante D, Hills NJ, Barnes CJ (2012) Thermo-Mechanical Finite Element Analysis/Computational Fluid Dynamics Coupling of an Interstage Seal Cavity Using Torsional Spring Analogy, Journal of Turbomachinery 134 (5)
The optimization of heat transfer between fluid and metal plays a crucial role in gas turbine design. An accurate prediction of temperature for each metal component can help to minimize the coolant flow requirement, with a direct reduction of the corresponding loss in the thermodynamic cycle. Traditionally, in industry fluid and solid simulations are conducted separately. The prediction of metal stresses and temperatures, generally based on finite element analysis, requires the definition of a thermal model whose reliability is largely dependent on the validity of the boundary conditions prescribed on the solid surface. These boundary conditions are obtained from empirical correlations expressing local conditions as a function of working parameters of the entire system, with validation being supplied by engine testing. However, recent studies have demonstrated the benefits of employing coupling techniques, whereby computational fluid dynamics (CFD) is used to predict the heat flux from the air to the metal, and this is coupled to the thermal analysis predicting metal temperatures. This paper describes an extension of this coupling process, accounting for the thermo-mechanical distortion of the metal through the engine cycle. Two distinct codes, a finite element analysis (FEA) solver for thermo-mechanical analysis and a finite volume solver for CFD, are iteratively coupled to produce temperatures and deformations of the solid part through an engine cycle. At each time step, the CFD mesh is automatically adapted to the FEA prediction of the metal position using efficient spring analogy methods, ensuring the continuity of the coupled process. As an example of this methodology, the cavity flow in a turbine stator well is investigated. In this test case, there is a strong link between the thermo-mechanical distortion, governing the labyrinth seal clearance, and the amount of flow through the stator well, which determines the resulting heat transfer in the stator well. This feedback loop can only be resolved by including the thermo-mechanical distortion within the coupling process. © 2012 American Society of Mechanical Engineers.
Amirante D, Hills NJ, Barnes CJ (2012) A moving mesh algorithm for aero-thermo-mechanical modelling in turbomachinery, International Journal for Numerical Methods in Fluids 70 (9) pp. 1118-1138 Wiley
This paper describes the development of a mesh deformation method used for aero-thermo-mechanical coupling of turbo-engine components. The method is based on the nonlinear solution of an elastic medium analogy, solved using finite element discretisation and modified to let the boundary nodes be free to slide over the deflected surfaces. This sliding technique relies on a B-spline reconstruction of the moving boundary and increases the robustness of the method in situations where the boundary deflection field presents significant gradients or large relative motion between two distinct boundaries. The performance of the method is illustrated with the application to an interstage cavity of a turbine assembly, subjected to the deformations computed by a coupled thermo-mechanical analysis of the engine component.
Amirante D, Hills NJ (2014) LES OF WALL BOUNDED TURBULENT FLOWS USING UNSTRUCTURED LINEAR RECONSTRUCTION TECHNIQUES, PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2014, VOL 2B AMER SOC MECHANICAL ENGINEERS
Montomoli F, Amirante D, Hills N, Shahpar S, Massini M (2014) UNCERTAINTY QUANTIFICATION, RARE EVENTS AND MISSION OPTIMIZATION: STOCHASTIC VARIATIONS OF METAL TEMPERATURE DURING A TRANSIENT, PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2014, VOL 5C AMER SOC MECHANICAL ENGINEERS
Amirante D, Hills NJ, Barnes CJ (2010) THERMO-MECHANICAL FEA/CFD COUPLING OF AN INTERSTAGE SEAL CAVITY USING TORSIONAL SPRING ANALOGY, PROCEEDINGS OF THE ASME TURBO EXPO 2010, VOL 4, PTS A AND B pp. 1037-1049 AMER SOC MECHANICAL ENGINEERS
Montomoli F, Amirante D, Hills N, Shahpar S, Massini M (2015) Uncertainty Quantification, Rare Events, and Mission Optimization: Stochastic Variations of Metal Temperature During a Transient, JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME 137 (4) ARTN 04210 ASME
Amirante D, Hills NJ (2015) Large-Eddy Simulations of Wall Bounded Turbulent Flows Using Unstructured Linear Reconstruction Techniques, JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME 137 (5) ARTN 05100 ASME
Chew J, Onori M, Amirante D, Hills N (2016) LES VALIDATION FOR A ROTATING CYLINDRICAL CAVITY WITH RADIAL INFLOW, Proceedings of ASME Turbo Expo 2016
This paper describes Large-Eddy Simulations (LES) of the flow in a rotating cavity with narrow inter-disc spacing and a radial inflow introduced from the shroud. Simulations have been conducted using a compressible, unstructured, finite-volume solver, and testing different subgrid scale models. These include the standard Smagorinsky model with Van Driest damping function near the wall, the WALE model and the implicit LES procedure. Reynolds averaged Navier-Stokes (RANS) results, based on the Spalart-Allmaras and SST k ? É models, are also presented. LES solutions reveal a turbulent source region, a laminar oscillating core with almost zero axial and radial velocity and turbulent Ekman type boundary layers along the discs. Validations are carried out against the experimental data available from the study of Firouzian et al. [1]. It is shown that the tangential velocity and the pressure drop across the cavity are very well predicted by both RANS and LES, although significant differences are observed in the velocity profiles within the boundary layers.
Amirante D, Hills NJ, Barnes CJ (2012) Use of dynamic meshes for transient metal temperature prediction, Proceedings of the ASME Turbo Expo 4 (PARTS A AND B) pp. 2073-2084
This paper describes the thermal analysis conducted on a three-dimensional model of a stator well contained within a turbine assembly. A methodology has been developed for coupled fluid-solid modelling accounting for the boundary deflections predicted by the structural analysis. The coupling is obtained through an iterative process between a finite element code (FEA) performing structural and thermal analysis for the solid part, and a finite volume solver for the CFD. As the engine runs transiently through a specified flight cycle, the FEA predictions of metal deformations and temperatures are passed to the CFD code, which in turns computes the heat fluxes over the metal surfaces. A robust moving mesh technique is used to automatically modify an initial mesh, based on the cold geometry, to the time dependent boundary deflections. Thus, the methodology guarantees that the CFD is always carried out on the hot-running geometry. A thorough investigation into the flow physics involved in the stator well is conducted. It is shown that an accurate thermal modelling for transient regimes necessitates the correct prediction of the time dependent clearances present in the system. Even small changes in the clearances may cause a transition between different dynamic behaviours, egress or ingestion, ultimately leading to drastically different thermal responses. Copyright © 2012 by ASME.
© 2015 .High fidelity simulations of the flow phenomena around complex geometries for turbomachinery applications require fluid solvers to run on ever increasing processor counts. For fully unsteady predictions in rotor-stator systems most of CFD codes employ the sliding interface technique. However, the scalability and efficiency of current sliding grid parallel implementations are significantly constrained by the computation and communication imbalances. They are associated with data transfer across discrete non-matching interfaces. To prepare for the challenges at extreme scales in this paper we attempt to redesign the algorithm in such a way that it maintains the scalability of the original CFD code on static grids. In the proposed parallel implementation the cell containment search and interpolation workloads are balanced by employing a deterministic geometric decomposition on an intermediate "rendezvous" set of processes. Rapidly changing dynamic communication patterns induced by the grids relative motion are handled with a sparse communication protocol. The scaling behavior and performance of the developed technique are analyzed using realistic test cases on two different computing systems.
Amirante D, Sun Z, Chew J, Hills N J, Atkins NR (2016) MODELING OF COMPRESSOR DRUM CAVITIES WITH RADIAL INFLOW, Proceedings of ASME Turbo Expo 2016
Reynolds-Averaged Navier-Stokes (RANS) computations have been conducted to investigate the ?ow and heat trans-fer between two co-rotating discs with an axial through?ow of cooling air and a radial bleed introduced from the shroud. The computational ?uid dynamics (CFD) models have been cou-pled with a thermal model of the test rig, and the predicted metal temperature compared with the thermocouple data. CFD solutions are shown to vary from a buoyancy driven regime to a forced convection regime, depending on the radial in?ow rate prescribed at the shroud. At a high radial in?ow rate, the computations show an excellent agreement with the measured temperatures through a transient rig condition. At a low radial in?ow rate, the cavity ?ow is destabilized by the thermal strati?cation. Good qualitative agreement with the measurements is shown, although a signi?cant over-prediction of disc temperatures is observed. This is associated with under prediction of the penetration of the axial through?ow into the cavity. The mismatch could be the result of strong sensitivity to the prescribed inlet conditions, in addition to possible shortcomings in the turbulence modeling.
Kumar R, Chew J, Amirante D, Murua J, Hills NJ (2017) CFD Simulation of Blade Flows With High Amplitude Pitching, Proceedings of ASME 2017: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy 9 ASME
Large and flexible wind turbine blades may be susceptible to severe blade deformations coupled with dynamic stall. To advance prediction capability for this problem a general deforming mesh computational fluid dynamics (CFD) method has been developed for calculating flows with moving or deforming boundaries using an elastic spring analogy. The method has been evaluated against experimental data for flow around a pitching NACA0012 airfoil in the deep dynamic stall regime where flow is highly separated, and compared with other authors0 CFD simulations for pitching airfoil. The effects of varying the reduced frequency are also investigated. During the upstroke the present results are in generally good agreement with experiment and other CFD studies. During the downstroke some differences with experiment and other CFD models are apparent. This may be due to the sensitivity of the separated flow to modelling assumptions and experimental conditions. Overall, the degree of agreement between CFD and experiment is considered encouraging.
Gao F, Chew J, Beard P, Amirante D, Hills NJ (2017) Numerical Studies of Turbine Rim Sealing Flows on a Chute Seal Configuration, Proceedings of 12th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
This paper presents CFD (computational fluid dynamics) modelling of a chute type rim seal that has been previously experimentally investigated. The study focuses on inherent large-scale unsteadiness rather than that imposed by vanes and blades or external flow. A large-eddy simulation (LES) solver is validated for a pipe flow test case and then applied to the chute rim seal rotor/stator cavity. LES, Reynolds-averaged Navier-Stokes (RANS) and unsteady RANS (URANS) models all showed reasonable agreement with steady measurements within the disc cavity, but only the LES shows unsteadiness at a similar distinct peak frequency to that found in the experiment, at 23 times the rotational frequency. However, there are some significant differences between unsteadiness predicted and the measurements, and possible causes of these are discussed.
Sun Zhili, Amirante Dario, Chew John, Hills Nicholas (2015) Coupled Aero-Thermal Modeling of a Rotating Cavity with Radial Inflow, Journal of Engineering for Gas Turbines and Power: Transactions of the ASME ASME
Gao Feng, Chew John, Beard Paul F., Amirante Dario, Hills Nicholas (2018) Large-eddy simulation of unsteady turbine rim sealing flows, International Journal of Heat and Fluid Flow 70 pp. 160-170 Elsevier
Unsteady flow phenomena unrelated to the main gas-path blading have been identified in a number of turbine rim seal investigations. This unsteadiness has significant influence on the sealing effectiveness predicted by the conventional steady RANS (Reynolds-averaged Navier?Stokes) method, thus it is important for turbine stage design and optimisation. This paper presents CFD (computational fluid dynamics) modelling of a chute type rim seal that has been previously experimentally investigated. The study focuses on inherent large-scale unsteadiness rather than that imposed by vanes and blades or external flow. A large-eddy simulation (LES) solver is validated for a pipe flow test case and then applied to the chute rim seal rotor/stator cavity. LES, RANS and unsteady RANS (URANS) models all showed reasonable agreement with steady measurements within the disc cavity, but only the LES shows unsteadiness at a similar distinct peak frequency to that found in the experiment, at 23 times the rotational frequency. The boundary layer profile within the chute rim seal clearance has been scrutinised, which may explain the improvement of LES over RANS predictions for the pressure drop across the seal. LES results show a clockwise mean flow vortex. A more detailed sketch of the rim sealing flow unsteady flow structures is established with the help of the LES results. However, there are some significant differences between unsteadiness predicted and the measurements, and possible causes of these are discussed.
Onori Michel, Amirante Dario, Hills Nicholas J., Chew John W. (2019) Heat transfer prediction from large eddy simulation of a rotating cavity with radial inflow, Proceedings of ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition GT 2019 American Society of Mechanical Engineers (ASME)
The paper describes a Large Eddy Simulation (LES) conducted for a non adiabatic rotating cavity with a radial inflow introduced from the shroud. The dimensionless mass flow rate of the radial inflow is Cw = 3500 and the rotational Reynolds number, based on the cavity outer radius, is equal to Req =1:2 x 106. The time averaged local Nusselt number on the heated wall is compared with the experimental data available from the literature, and with those derived from the solution of two Unsteady Reynolds Averaged Navier-Stokes (URANS) eddy viscosity models, namely the Spalart-Allmaras and the k-w SST model. It is shown that the Nusselt number is underpredicted
in the lower part of the disc and over-predicted in the outer region by both URANS models, whereas the LES provides a much better agreement with the measurements. The behaviour results primarily from a different flow structure in the source region, which, in the LES, is found to be considerably more extended and show localized buoyancy phenomena that the URANS models investigated do not capture.
Onori Michel, Amirante Dario, Hills Nicholas J., Chew John W. (2019) Heat Transfer Prediction from Large Eddy Simulation of a Rotating Cavity with Radial Inflow, Journal of Engineering for Gas Turbines and Power American Society of Mechanical Engineers (ASME)
The paper describes a Large Eddy Simulation (LES) conducted for a non adiabatic rotating
cavity with a radial inflow introduced from the shroud. The dimensionless mass flow rate of the
radial inflow is Cw = 3500 and the rotational Reynolds number, based on the cavity outer radius, is equal to Re¸ = 1.2 x 10v. The time averaged local Nusselt number on the heated wall is compared
with the experimental data available from the literature, and with those derived from the solution
of two Unsteady Reynolds Averaged Navier-Stokes (URANS) eddy viscosity models, namely the
Spalart-Allmaras and the k - É SST model. It is shown that the Nusselt number is under-predicted
in the lower part of the disc and over-predicted in the outer region by both URANS models, whereas
the LES provides a much better agreement with the measurements. The behaviour results primarily
from a different flow structure in the source region, which, in the LES, is found to be considerably
more extended and show localized buoyancy phenomena that the URANS models investigated do
not capture.