Publications
137 results found
Casari N, Pinelli M, Suman A, et al., 2017, Gas turbine blade geometry variation due to fouling, ETC, ISSN: 2410-4833
Copyright © by the Authors. Solid particles ingestion is a severe problem for gas turbines. In the aero-propulsion field the main problems related to this phenomenon occur on the hot sections of the machinery. Impinging particles can stick or Erode the blade material. The deposition on the turbine blades is the main issue among the two and the clogging of cooling holes can even speed up this process rising the blade surface temperature. An higher temperature affects negatively the deposition problems, increasing particle stickiness. In this paper an innovative approach to account for fouling and erosion effects on turbine vanes is presented. An energetic model to predict the sticking probability is used (EBFOG, from Energy Based FOulinG) and the erosion is evaluated through the model proposed by Tabakoff. Geometry variation of blades subject to fouling are investigated by means of a moving mesh technique which accounts for the boundary displacement of the blade surface.
ahlfeld, laizet, Geraci G, et al., 2016, Multi-Fidelity Uncertainty Quanti cation Using RANS and DNS, CTR Stanford Summer Program
Ahlfeld R, Montomoli F, 2016, A Single Formulation For Uncertainty Propagation in Turbomachinery: SAMBA, ASME Turbo Expo 2016
Montomoli F, pietropaoli M, ahlfeld R, et al., 2016, DESIGN FOR ADDITIVE MANUFACTURING: INTERNAL CHANNEL OPTIMIZATION, ASME IGTI Turbo Expo 2016
Ahlfeld R, Belkouchi B, Montomoli F, 2016, SAMBA: Sparse Approximation of Moment-Based Arbitrary Polynomial Chaos, Journal of Computational Physics, Vol: 320, Pages: 1-16, ISSN: 0021-9991
A new arbitrary Polynomial Chaos (aPC) method is presented for moderately high-dimensional problems characterised by limited input data availability. The proposed methodology improves the algorithm of aPC and extends the method, that was previously only introduced as tensor product expansion, to moderately high-dimensional stochastic problems. The fundamental idea of aPC is to use the statistical moments of the input random variables to develop the polynomial chaos expansion. This approach provides the possibility to propagate continuous or discrete probability density functions and also histograms (data sets) as long as their moments exist, are finite and the determinant of the moment matrix is strictly positive. For cases with limited data availability, this approach avoids bias and fitting errors caused by wrong assumptions. In this work, an alternative way to calculate the aPC is suggested, which provides the optimal polynomials, Gaussian quadrature collocation points and weights from the moments using only a handful of matrix operations on the Hankel matrix of moments. It can therefore be implemented without requiring prior knowledge about statistical data analysis or a detailed understanding of the mathematics of polynomial chaos expansions. The extension to more input variables suggested in this work, is an anisotropic and adaptive version of Smolyak's algorithm that is solely based on the moments of the input probability distributions. It is referred to as SAMBA (PC), which is short for Sparse Approximation of Moment-Based Arbitrary Polynomial Chaos. It is illustrated that for moderately high-dimensional problems (up to 20 different input variables or histograms) SAMBA can significantly simplify the calculation of sparse Gaussian quadrature rules. SAMBA's efficiency for multivariate functions with regard to data availability is further demonstrated by analysing higher order convergence and accuracy for a set of nonlinear test functions with 2, 5 and 10 diffe
Mazzoni C, Ahlfeld R, Rosic B, et al., 2016, Uncertainty quantification of leakages in a multistage simulation and comparison with experiments, Journal of Fluids Engineering-Transactions of the ASME, ISSN: 0098-2202
The present paper presents a numerical study of the impact of tip gap uncertainties in a multistage turbine. It is well known that the rotor gap can change the gas turbine efficiencybut the impact of the random variation of the clearance height has not been investigated before.In this paper the radial seals clearance of a datum shroud geometry, representative of steam turbine industrial practice, wassystematically varied and numerically tested.By using a Non-Intrusive Uncertainty Quantification simulation based on a Non-Intrusive Polynomial Chaos, it is possible to predict the radial distribution of uncertainty in stagnation pressure and yaw angle at the exit of the turbine blades.This work shows that the impact of gap uncertainties propagates radially from the tip towards the hub of the turbine and the complete span is affected by a variation of the rotor tip gap. This amplification of the uncertainty is mainly due to the low aspect ratio of the turbine and a similar behavior is expected in high pressure turbines.
Ahlfeld R, Montomoli F, Scalas E, et al., 2016, Uncertainty Quantification for Fat-Tailed Probability Distributions in Aircraft Engine Simulations, Journal of Propulsion and Power
Mazzoni CM, Ahlfeld R, Rosic B, et al., 2016, Uncertainty quantification of leakages in a multistage simulation and comparison with experiments, Isromac- 16th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, Publisher: ISROMAC
The present paper presents a numerical study of the impact of tip gap uncertainties in a multistageturbine. It is well known that the rotor gap can change the gas turbine efficiency but the impact of therandom variation of the clearance height has not been investigated before.In this paper the radial seals clearance of a datum shroud geometry, representative of steam turbineindustrial practice, was systematically varied and numerically tested. By using a Non-IntrusiveUncertainty Quantification simulation based on a Sparse Arbitrary Moment Based Approach, it ispossible to predict the radial distribution of uncertainty in stagnation pressure and yaw angle at the exitof the turbine blades.This work shows that the impact of gap uncertainties propagates radially from the tip towards the hub ofthe turbine and the complete span is affected by a variation of the rotor tip gap. This amplification of theuncertainty is mainly due to the low aspect ratio of the turbine and a similar behavior is expected in highpressure turbines.
casari N, pinelli M, suman A, et al., 2016, AN ENERGY BASED FOULING MODEL FOR GAS TURBINES: EBFOG, ASME IGTI Turbo Expo 2016
Salvadori S, Cappelletti A, Montomoli F, et al., 2015, Experimental and numerical evaluation of the NPSH<inf>R</inf> curve of an industrial centrifugal pump, ISSN: 2410-4833
Cavitation triggers harmful flow instabilities yielding both significant decrease of performance and reduced reliability. The aim of this paper is to investigate the accuracy of numerical methodologies for the correct prediction of cavitation inception in centrifugal pumps. Preliminary analyses are performed on the NACA 0009 hydrofoil using the ANSYS CFX V14.5 code. The available bubble dynamics model is calibrated using the experimental data in cavitation conditions. Then, the optimized parameters are used for the evaluation of the NPSHR curve of the R250 centrifugal pump industrial pump designed by WEIRGabbioneta srl. Reynolds-Averaged Navier-Stokes mono- and two-phase calculations are performed. The performance curve of the R250 centrifugal pump is evaluated at first, and then the NPSHR curve is obtained for the design flow rate. The control volume of the numerical analysis includes all the hydraulic features from flange to flange (except for the side chambers) and then a direct comparison with the available experimental data obtained during two experimental campaigns is possible. The numerical activity demonstrated that an adequately calibrated model is able to reproduce the shape of the cavitation curve of an industrial centrifugal pump, although the NPSHR value is underestimated.
Montomoli F, Amirante D, Hills N, et al., 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
Salvadori S, Cappelletti A, Montomoli F, et al., 2015, Experimental and numerical evaluation of the NPSH<inf>R</inf> curve of an industrial centrifugal pump, ISSN: 2313-0067
Cavitation triggers harmful flow instabilities yielding both significant decrease of performance and reduced reliability. The aim of this paper is to investigate the accuracy of numerical methodologies for the correct prediction of cavitation inception in centrifugal pumps. Preliminary analyses are performed on the NACA 0009 hydrofoil using the ANSYS CFX V14.5 code. The available bubble dynamics model is calibrated using the experimental data in cavitation conditions. Then, the optimized parameters are used for the evaluation of the NPSHR curve of the R250 centrifugal pump industrial pump designed by WEIRGabbioneta srl. Reynolds-Averaged Navier-Stokes mono- and two-phase calculations are performed. The performance curve of the R250 centrifugal pump is evaluated at first, and then the NPSHR curve is obtained for the design flow rate. The control volume of the numerical analysis includes all the hydraulic features from flange to flange (except for the side chambers) and then a direct comparison with the available experimental data obtained during two experimental campaigns is possible. The numerical activity demonstrated that an adequately calibrated model is able to reproduce the shape of the cavitation curve of an industrial centrifugal pump, although the NPSHR value is underestimated.
Salvadori S, Cappelletti A, Montomoli F, et al., 2015, Experimental and numerical evaluation of the NPSH<inf>R</inf>curve of an industrial centrifugal pump
Cavitation triggers harmful flow instabilities yielding both significant decrease of performance and reduced reliability. The aim of this paper is to investigate the accuracy of numerical methodologies for the correct prediction of cavitation inception in centrifugal pumps. Preliminary analyses are performed on the NACA 0009 hydrofoil using the ANSYS CFX V14.5 code. The available bubble dynamics model is calibrated using the experimental data in cavitation conditions. Then, the optimized parameters are used for the evaluation of the NPSH R curve of the R250 centrifugal pump industrial pump designed by WEIRGabbioneta srl. Reynolds-Averaged Navier-Stokes mono- and two-phase calculations are performed. The performance curve of the R250 centrifugal pump is evaluated at first, and then the NPSH R curve is obtained for the design flow rate. The control volume of the numerical analysis includes all the hydraulic features from flange to flange (except for the side chambers) and then a direct comparison with the available experimental data obtained during two experimental campaigns is possible. The numerical activity demonstrated that an adequately calibrated model is able to reproduce the shape of the cavitation curve of an industrial centrifugal pump, although the NPSH R value is underestimated.
Salvadori S, Cappelletti A, Montomoli F, et al., 2015, EXPERIMENTAL AND NUMERICAL EVALUATION OF THE NPSHR CURVE OF AN INDUSTRIAL CENTRIFUGAL PUMP, 11th EUROPEAN CONFERENCE ON TURBOMACHINERY FLUID DYNAMICS AND THERMODYNAMICS, Publisher: EUROPEAN TURBOMACHINERY SOC-EUROTURBO
Montomoli F, Insinna M, Cappelletti A, et al., 2015, UNCERTAINTY QUANTIFICATION AND STOCHASTIC VARIATIONS OF RENEWABLE FUELS, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
Bradford J, Montomoli F, D'Ammaro A, 2014, Uncertainty quantification and race car aerodynamics, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART D-JOURNAL OF AUTOMOBILE ENGINEERING, Vol: 228, Pages: 403-411, ISSN: 0954-4070
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- Citations: 5
Carnevale M, D'Ammaro A, Montomoli F, et al., 2014, FILM COOLING AND SHOCK INTERACTION: AN UNCERTAINTY QUANTIFICATION ANALYSIS WITH TRANSONIC FLOWS, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
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- Citations: 7
Montomoli F, D'Ammaro A, Uchida S, 2013, Numerical and experimental investigation of a new film cooling geometry with high P/D ratio, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, Vol: 66, Pages: 366-375, ISSN: 0017-9310
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- Citations: 23
Salvadori S, Montomoli F, Martelli F, et al., 2013, Analysis on the Effect of a Nonuniform Inlet Profile on Heat Transfer and Fluid Flow in Turbine Stages (vol 134, 011012, 2012), JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME, Vol: 135, ISSN: 0889-504X
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- Citations: 1
Carnevale M, Montomoli F, D'Ammaro A, et al., 2013, Uncertainty Quantification: A Stochastic Method for Heat Transfer Prediction Using LES, JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME, Vol: 135, ISSN: 0889-504X
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- Citations: 48
Salvadori S, Montomoli F, Martelli F, 2013, Film-cooling performance in supersonic flows: effect of shock impingement, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY, Vol: 227, Pages: 295-305, ISSN: 0957-6509
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- Citations: 7
Montomoli F, D'Ammaro A, Uchida S, 2013, Uncertainty Quantification and Conjugate Heat Transfer: A Stochastic Analysis, JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME, Vol: 135, ISSN: 0889-504X
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- Citations: 17
D'Ammaro A, Montomoli F, 2013, Uncertainty quantification and film cooling, COMPUTERS & FLUIDS, Vol: 71, Pages: 320-326, ISSN: 0045-7930
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- Citations: 25
Montomoli F, Naylor E, Hodson HP, et al., 2013, Unsteady Effects in Axial Compressors: A Multistage Simulation, JOURNAL OF PROPULSION AND POWER, Vol: 29, Pages: 1001-1008, ISSN: 0748-4658
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- Citations: 10
Montomoli F, Massini M, 2013, GAS TURBINES AND UNCERTAINTY QUANTIFICATION: IMPACT OF PDF TAILS ON UQ PREDICTIONS, THE BLACK SWAN, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
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- Citations: 5
Montomoli F, Massini M, Yang H, et al., 2012, The benefit of high-conductivity materials in film cooled turbine nozzles, INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW, Vol: 34, Pages: 107-116, ISSN: 0142-727X
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- Citations: 28
Simone S, Montomoli F, Martelli F, et al., 2012, Analysis on the Effect of a Nonuniform Inlet Profile on Heat Transfer and Fluid Flow in Turbine Stages, JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME, Vol: 134, ISSN: 0889-504X
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- Citations: 52
Montomoli F, Massini M, Salvadori S, et al., 2012, Geometrical Uncertainty and Film Cooling: Fillet Radii, JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME, Vol: 134, ISSN: 0889-504X
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- Citations: 35
Montomoli F, D'Ammaro A, Uchida S, 2012, UNCERTAINTY QUANTIFICATION AND CONJUGATE HEAT TRANSFER: A STOCHASTIC ANALYSIS, ASME Turbo Expo 2012, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 99-+
Carnevale M, Montomoli F, D'Ammaro A, et al., 2012, UNCERTAINTY QUANTIFICATION: A STOCHASTIC METHOD FOR HEAT TRANSFER PREDICTION USING LES, ASME Turbo Expo 2012, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 59-+
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