49 results found
Lu G, Wang F, di Mare L, et al., 2018, Data re-use for preliminary thermal-mechanical design of gas turbine engines, AERONAUTICAL JOURNAL, Vol: 122, Pages: 462-486, ISSN: 0001-9240
Jelly TO, Day IJ, di Mare L, 2017, Phase-averaged flow statistics in compressors using a rotated hot-wire technique, Experiments in Fluids, Vol: 58, ISSN: 0723-4864
A technique based on a rotated hot wire has been developed to characterise the unsteady, three-dimensional flow field between compressor blade rows. Data are acquired from a slanted hot wire rotated through a number of orientations at each measurement point. Phase-averaged velocity statistics are obtained by solving a set of sensor response equations using a weighted, non-linear regression algorithm. The accuracy and robustness of the method were verified a priori by conducting a series of tests using synthetic data. The method is demonstrated by acquiring a full set of phase-averaged flow statistics in the wake of a compressor stator blade row. The technique allows three components of phase-averaged velocity, six components of phase-averaged deterministic stress, and six components of phase-averaged Reynolds stress to be recovered using a single rotated hot-wire probe.
Carnevale M, Wang F, di Mare L, 2017, Low Frequency Distortion in Civil Aero-engine Intake, JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME, Vol: 139, ISSN: 0742-4795
Casari N, Pinelli M, Suman A, et al., 2017, Gas turbine blade geometry variation due to fouling, European Turbomachinery Conference
Casari N, Pinelli M, Suman A, et al., 2017, An energy based fouling model for gas turbines: EBFOG, Journal of Turbomachinery - Transactions of the ASME, Vol: 139, Pages: 021002-1-021002-8, ISSN: 0889-504X
Fouling is a major problem in gas turbines for aeropropulsionbecause the formation of aggregates on the wet surfacesof the machine affects aerodynamic and heat loads.The representation of fouling in CFD is based on the evaluationof the sticking probability, i.e. the probability a particletouching a solid surface has to stick to that surface. Two mainmodels are currently available in literature for the evaluation ofthe sticking coefficient: one is based on a critical threshold forthe viscosity, the other is based on the normal velocity to thesurface. However, both models are application specific and lackgenerality.This work presents an innovative model for the estimationof the sticking probability. This quantitiy is evaluated by comparingthe kinetic energy of the particle with an activation energywhich describes the state of the particle. The sticking criteriontakes the form of an Arrhenius-type equation. A general formulationfor the sticking coefficient is obtained. The method,named EBFOG (Energy Based FOulinG), is the first ”energy”based model presented in the open literature able to account anycommon deposition effect in gas turbines.The EBFOG model is implemented into a Lagrangian trackingprocedure, coupled to a fully three-dimensional CFD solver.Particles are tracked inside the domain and equations for the momentumand temperature of each particle are solved. The localgeometry of the blade is modified accordingly to the deposition rate. The mesh is modified and the CFD solver updates the flowfield.The application of this model to particle deposition in highpressure turbine vanes is investigated, showing the flexibility ofthe proposed methodology. The model is particularly importantin aircraft engines where the effect of fouling for the turbine, inparticular the reduction of the HP nozzle throat area, influencesheavily the performance by reducing the core capacity. The energybased approach is used to quantify the throat area reductionrate and estimate
Di Mare L, Jelly TO, Day IJ, 2017, Angular response of hot-wire probes, Measurement Science & Technology, Vol: 28, ISSN: 1361-6501
A new equation for the convective heat loss from the sensor of a hot-wire probe is derived which accountsfor both the potential and the viscous parts of the ow past the prongs. The convective heat loss from thesensor is related to the far- eld velocity by an expression containing a term representing the potential owaround the prongs, and a term representing their viscous e ect. This latter term is absent in the responseequations available in the literature but is essential in representing some features of the observed responseof miniature hot-wire probes. The response equation contains only four parameters but it can reproduce,with great accuracy, the behaviour of commonly used single-wire probes. The response equation simpli esthe calibration the angular response of rotated slanted hot-wire probes: only standard King's law parametersand a Reynolds-dependent drag coefficient need to be determined.
Carnevale M, Wang F, Parry AB, et al., 2017, FAN SIMILARITY MODEL FOR THE FAN-INTAKE INTERACTION PROBLEM, ASME Turbine Technical Conference and Exposition (Turbo Expo), Publisher: AMER SOC MECHANICAL ENGINEERS
Wang F, di Mare L, 2016, Hybrid meshing using constrained Delaunay triangulation for viscous flow simulations, International Journal for Numerical Methods in Engineering, Vol: 108, Pages: 1667-1685, ISSN: 0029-5981
In this paper, we present a generalized prismatic hybrid meshing method for viscous flow simulations.One major difficulty in implementing a robust prismatic hybrid meshing tool is to handle boundarylayer mesh collisions and normally an extra data structure (e.g. quadtree in 2D and octree in 3D) isrequired. The proposed method overcomes this difficulty via an heuristic approach and it only relieson Constrained Delaunay Triangulation/Tetrahedralization(CDT). No extra data structures are required.Geometrical reasoning is used to approximate the maximum marching distance of each point by walkingthrough the CDT. This is combined with post-processing of marching vectors and distance and prohibition ofmultilevel differences to form an automatic and robust mechanism to remove boundary layer mesh collisions.Benefiting from the matureness of CDT techniques, the proposed method is robust, efficient and simpleto implement. Its capability is demonstrated by generating quality prismatic hybrid meshes for industrialmodels with complex geometries. The proposed method is believed to be able considerably reduce the effortto implement a robust hybrid prismatic mesh generator for viscous flow simulations.
Wang F, Carnevale M, Lu G, et al., 2016, Virtual Gas Turbine: Pre-Processing and Numerical Simulations, ASME Turbo Expo 2016, Publisher: ASME, Pages: GT2016-56227-GT2016-56227
The design process of a gas turbine engine involves interrelated multi-disciplinary and multi-fidelity designs of engine components. Traditional component-based design process is not always able to capture the complicated physical phenomenon caused by component interactions. It is likely that such interactions are not resolved until hardware is built and tests are conducted. Component interactions can be captured by assembling all these components into one computational model. Nowadays, numerical solvers are fairly easy to use and the most time-consuming (in terms of man-hours) step for large scale gas turbine simulations is the preprocessing process. In this paper, a method is proposed to reduce its time-cost and make large scale gas turbine numerical simulations affordable in the design process. The method is based on a novel featured-based in-house geometry database. It allows the meshing modules to not only extract geometrical shapes of a computational model and additional attributes attached to the geometrical shapes as well, such as rotational frames, boundary types, materials, etc. This will considerably reduce the time-cost in setting up the boundary conditions for the models in a correct and consistent manner. Furthermore, since all the geometrical modules access to the same geometrical database, geometrical consistency is satisfied implicitly. This will remove the time-consuming process of checking possible mismatching in geometrical models when many components are present. The capability of the proposed method is demonstrated by meshing the whole gas path of a modern three-shaft engine and the Reynold’s Averaged Navier-Stokes (RANS) simulation of the whole gas path.
Hadade IC, di Mare L, 2016, Modern Multicore and Manycore Architectures: modelling, optimisation and benchmarking a multiblock CFD code, Computer Physics Communications, Vol: 205, Pages: 32-47, ISSN: 1879-2944
Modern multicore and manycore processors exhibit multiple levels of parallelismthrough a wide range of architectural features such as SIMD for data parallelexecution or threads for core parallelism. The exploitation of multi-level parallelismis therefore crucial for achieving superior performance on current andfuture processors. This paper presents the performance tuning of a multiblockCFD solver on Intel SandyBridge and Haswell multicore CPUs and the IntelXeon Phi Knights Corner coprocessor. Code optimisations have been appliedon two computational kernels exhibiting different computational patterns: theupdate of flow variables and the evaluation of the Roe numerical fluxes. Wediscuss at great length the code transformations required for achieving effi-cient SIMD computations for both kernels across the selected devices includingSIMD shuffles and transpositions for flux stencil computations and global memorytransformations. Core parallelism is expressed through threading basedon a number of domain decomposition techniques together with optimisationspertaining to alleviating NUMA effects found in multi-socket compute nodes.Results are correlated with the Roofline performance model in order to asserttheir efficiency for each distinct architecture. We report significant speedupsfor single thread execution across both kernels: 2-5X on the multicore CPUsand 14-23X on the Xeon Phi coprocessor. Computations at full node and chipconcurrency deliver a factor of three speedup on the multicore processors andup to 24X on the Xeon Phi manycore coprocessor.
casari N, pinelli M, suman A, et al., 2016, AN ENERGY BASED FOULING MODEL FOR GAS TURBINES: EBFOG, ASME IGTI Turbo Expo 2016
Barbarossa F, Parry AB, Green JS, et al., 2016, An Aerodynamic Parameter for Low-Pressure Turbine Flutter, Journal of Turbomachinery-Transactions of the ASME, Vol: 138, ISSN: 1528-8900
Rife ME, Barbarossa F, Parry AB, et al., 2016, MINIMISATION OF DUCTED FLOW NON-UNIFORMITY CAUSED BY DOWNSTREAM BLOCKAGES, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
Carnevale M, Wang F, di Mare L, 2016, LOW FREQUENCY DISTORTION IN CIVIL AERO-ENGINE INTAKE, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
Stapelfeldt SC, Di Mare L, 2015, Reduced passage method for multirow forced response computations, AIAA Journal: devoted to aerospace research and development, Vol: 53, Pages: 3049-3062, ISSN: 0001-1452
This paper presents a time-domain Fourier method for modeling steady and unsteady nonaxisymmetric flows in turbomachinery on a reduced computational domain. The method extends well-established single-passage multirow methods, which efficiently model periodic unsteadiness in single stages, to assemblies with stationary circumferential perturbations with periodicity different from the blade count. Such perturbations are caused, for example, by rotor–rotor/stator–stator interaction or geometric circumferential variations. The method is therefore suitable to study low-engine-order forcing problems, flow past nonuniform assemblies, and clocking problems. The proposed method solves the flow inside several discrete passages, located at different circumferential positions, using a time-accurate scheme. Boundary conditions at the azimuthal and interrow surfaces are approximated via time–space Fourier series and couple the individual passages. The reduced passage model is validated against the whole annulus solution for three test cases: 1) a row of outlet guide vanes with stagger pattern, 2) a high-pressure turbine stage with throat area variation in the stator, and 3) a 1.5-stage compressor. It is demonstrated that the time-domain Fourier method yields results equivalent to the whole annulus model but at a much reduced computational cost.
Hadade IC, di Mare L, 2014, Exploiting SIMD and Thread-Level Parallelism in Multiblock CFD, International Supercomputing Conference, ISC'14, Publisher: Springer International Publishing, Pages: 410-419, ISSN: 0302-9743
Ponjavic A, di Mare L, Wong J, 2014, Effect of pressure on the flow behavior of polybutene, Journal of Polymer Science Part B: Polymer Physics, Vol: 52, Pages: 708-715, ISSN: 0887-6266
The rheology of submicron thick polymer melt is examined under high normal pressure conditions by a recently developed photobleached‐fluorescence imaging velocimetry technique. In particular, the validity and limitation of Reynold equation solution, which suggests a linear through‐thickness velocity profile, is investigated. Polybutene (PB) is sheared between two surfaces in a point contact. The results presented in this work suggest the existence of a critical pressure below which the through‐thickness velocity profile is close to linear. At higher pressures however, the profile assumes a sigmoidal shape resembling partial plug flow. The departure of the sigmoidal profile from the linear profile increases with pressure, which is indicative of a second‐order phase/glass transition. The nature of the transition is confirmed independently by examining the pressure‐dependent dynamics of PB squeeze films. The critical pressure for flow profile transition varies with molecular weight, which is consistent with the pressure‐induced glass transition of polymer melt.
Carnevale M, Green JS, Di Mare L, 2014, NUMERICAL STUDIES INTO INTAKE FLOW FOR FAN FORCING ASSESSMENT, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
Di Mare L, Thirumurthy D, Green JS, et al., 2014, UNSTEADY AERODYNAMICS AND FORCED RESPONSE STUDIES ON AERODERIVATIVE GAS TURBINE EXHAUST SYSTEM, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
Botta F, Dini D, Schwingshackl C, et al., 2013, Optimal Placement of Piezoelectric Plates to Control Multimode Vibrations of a Beam, Advances in Acoustics and Vibration, Vol: 2013, ISSN: 1687-627X
Damping of vibrations is often required to improve both the performance and the integrity of engineering structures, for example, gas turbine blades. In this paper, we explore the possibility of using piezoelectric plates to control the multimode vibrations of a cantilever beam. To develop an effective control strategy and optimize the placement of the active piezoelectric elements in terms of vibrations amplitude reduction, a procedure has been developed and a new analytical solution has been proposed. The results obtained have been corroborated by comparison with the results from a multiphysics finite elements package (COMSOL), results available in the literature, and experimental investigations carried out by the authors. © 2013 Fabio Botta et al.
Romanov A, Di Mare L, 2013, EXTENDED TURBOMACHINERY AEROMECHANICAL MODEL, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
Wang F, Di Mare L, 2013, Automated hex meshing for turbomachinery secondary air system, Pages: 549-566
In this paper, we present a novel process of creating hexahedral meshes for the turbomachinery secondary air system. The meshing process is automated from the geometry import to the mesh setup and requires minimum human interventions. The core of the process is a hexahedral meshing algorithm with a boundary layer mesh automatically created. The hex meshing algorithm combines the pave-sweep, general sheet-insertion and a novel technique which creates the boundary layer mesh by carefully placing, maintaining and dicing a buffer layer around a geometry. After the mesh is created, relevant boundary conditions for the mesh are also assigned automatically. The whole meshing process is systematically automated and has the potential to considerably reduce the time cost in meshing the turbomachinery secondary air system.
Stapelfeldt SC, di Mare L, 2013, MODELLING ROTOR-ROTOR INTERACTION ON REDUCED PASSAGE COUNTS USING A TIME-DOMAIN FOURIER APPROACH, 10th European Conference on Turbomachinery: Fluid Dynamics and Thermodynamics, Publisher: EUROPEAN TURBOMACHINERY SOC-EUROTURBO
Stapelfeldt SC, di Mare L, 2013, MODELLING ROTOR-ROTOR/STATOR-STATORINTERACTIONS ON REDUCED PASSAGE COUNTS, European Turbomachinery Conference
Blade row interaction is known to significantly affect aerodynamic performance and aeromechanicalstability. Multi-stage flows can be modelled accurately on the whole annulus multistagedomain. However, full circumference time-accurate simulations remain expensive andunpractical in the design cycle. This paper uses a time-domain Fourier based method to modelsteady and unsteady interaction effects in a two stage compressor. The method was developedfor general non-axisymmetric flows across multiple blade rows. The computational domain includesseveral passages which are distributed over one wavelength of the fundamental stationarydisturbance and act as sampling points for a circumferential Fourier transform. Flow variablesat the pitch-wise boundaries and inlet/exit surfaces are updated from circumferential andtemporal Fourier approximations. Results from the reduced passage model and whole annulussolutions are compared in terms of unsteady and time-averaged loads. The results demonstratethat the time-domain Fourier approach is capable of capturing steady and unsteady blade rowinteraction effects.
Romanov A, di Mare L, 2013, Extended one-dimensional turbomachinery performance model (several bladerows), IGTI ASME TurboExpo 2013
An extended version of the previously presented linearized one-dimensional turbomachinery performance model is described. The current version of the model is capable of performing forced response and flutter simulations on several stationary and/or rotating bladerows. The amplitude of the perturbation is assumed small thus impact of the perturbations of several sources may be superimposed. The distortion propagation analysis may be performed in the early stages of the design process, or whenever a quick solution is desirable, having only minimal information about the studied geometry.The approach has a block structure, where each block represents a bladed passage or the empty space between. The blocks contain linearized gas relations that relate the gas state to known changes of enthalpy, entropy and momentum. The blade blocks are represented using the extended semi-actuator disk theory, where the flow inside the passage assumed to be one-dimensional . The model considers frequency scattering for the rotating bladerows and is also using a complete package of linearized loss- and deviation correlations, providing more realistic results. The approach extends the previously presented methods by Amiet ,  and Kaji&Okazaki , , being capable to handle harmonic distortions of various wavelength-to-chord ratios. Minimal assumptions are made about the studied geometry and nature of the gas, allowing to perform unsteady flow analysis not only on the idealized cases, but on more complex, realistic geometry.Appropriate non-reflecting boundary conditions are applied at the boundaries of each block, using the hyperbolic characteristic theory, thus facilitating multi-blaredow domains setup and allowing running more complex cases, involving both forced response and flutter.A number of idealized cases presented by Amiet and Kaji & Okazaki are reproduced to validate the model against the reference data, where a good comparison is achieved. The approach is also t
Phibel R, di Mare L, 2012, COMPARISON BETWEEN A CFD CODE AND A THREE CONTROL-VOLUME MODEL FOR LABYRINTH SEAL FLUTTER PREDICTIONS, ASME Turbo Expo 2011, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 597-606
Botta F, Marx N, Gentili S, et al., 2012, Optimal placement of piezoelectric plates for active vibration control of gas turbine blades: experimental results, SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2012, PTS 1 AND 2, Vol: 8345, ISSN: 0277-786X
Romanov A, di Mare L, 2012, Exact linearization of one-dimensional turbomachinery performance model, ISUAAAT 13
A generic, linearized one-dimensional innovative approach for the small-amplitude distortion propagation across the compressor blades is described. The model is capable of performing forced response and flutter simulations, trying to match other performance and wave propagation models. A basic model, presented by Kaji & Okazaki  is extended to handle arbitrary compressor blade and annulus geometry with minimal assumptions and to account for total pressure losses as well as the outlet flow angle deviations. The theory displays increased sensitivity in forced response cases of incident acoustic waves with very long and very short wavelengths compared to chord. It also provides better estimation of the reflection and transmission coefficients in near and in the cut-off regions. The model is capable of performing first-order modes flutter simulations and also has the interface for multi-bladerow analysis.A number of validation cases have been performed, showing the increased sensitivity of the model, as well as displaying its application on the real compressor geometry for estimating the blade forcing and effect on the flow due to the forced response.
Stapelfeldt SC, di Mare L, 2012, A METHOD FOR MODELLING FLOW PAST NON-AXISYMMETRIC CONFIGURATIONS ON REDUCED PASSAGE COUNTS, ISUAAAT 13
Advanced gas turbine and aeroengine designs require accurate computational methods to predict aerothermal and aeroelastic behaviour. The full unsteady flow field can be modelled accurately using time-accurate full circumference multi-row methods. Over the past few decades, much progress has been made in the development of single passage methods which take advantage of the well defined time-space periodicity in turbomachines.These single-passage multi-row methods successfully model unsteadiness due to rotor-stator interaction or blade vibration. However, limitations apply to the representation of interactions between more than two blade rows; Unequal blade counts of rows in the same frame of reference, geometrical variations and distortions can create steady circumferential non-uniformities which cannot be captured by single passage methods as no phase-shifted temporal periodicity exists. This has led to the development of more advanced time-domain Fourier methods capable of modelling non-axisymmetric flows.In this paper we extend the time-domain Fourier method to aerodynamically mistuned assemblies and multiple blade rows. In order to represent steady circumferential variations, several passages are distributed over one circumferential wavelength of the disturbance. Flow variables at periodic boundaries and blade row interfaces are decomposed into spatial and temporal Fourier coefficients which are continuously updated using a partial substitution technique. The boundary conditions at the periodic and inlet/exit surfaces are then corrected from the Fourier components. A phase correction is applied when reconstructing reflected disturbances on the inter-row boundaries in the multi-passage domain. This renders the position of the passages arbitrary with respect to the physical assembly such that even small wavelengths can be represented on a comparatively small number of passages. The order of the Fourier approximation then only depends on the number of passages used
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