Papers by Stefano D’Ambrosio
SAE Technical Paper Series, Oct 21, 2002
Applied Energy, Oct 1, 2014
Tire inflation pressure affects vehicle energetic balance, as well as road safety. These issues a... more Tire inflation pressure affects vehicle energetic balance, as well as road safety. These issues are particularly critical due to the low attention paid by the drivers to tire maintenance. Tire pressure monitoring systems are used to alert the drivers in case of low pressure, but higher benefits could be obtained through a completely autonomous onboard system capable of setting the optimal tire pressure according to current working conditions and of automatically inflate or deflate tires. Basing on computer simulations on fuel economy of a reference mid-size diesel passenger car, and referring to statistical data on vehicle use, the potentialities of such a device is evaluated on an annual mission. The results are then extended to the whole European fleet to provide an estimation of the potential benefits that could be obtained through massive adoption of this solution. The impact is evaluated through an economical evaluation of: fuel savings, reduction of social cost of carbon emissions, increase of tire life and reduction of costs related to crashes produced by improper tire pressure.
The paper investigates cyclic variability in a fast-burn engine running on both gasoline or CNG b... more The paper investigates cyclic variability in a fast-burn engine running on both gasoline or CNG by applying a new diagnostic technique based on a quasi-dimensional multizone model. Two different procedures were proposed for the ‘cycle-resolved’ calibration of the heat transfer correlation in the multizone model. The first procedure relates the cycle-resolved unreleased energy of the charge at the end of the flame propagation to the combustion efficiency determined from the average exhaust gas composition. The second procedure evaluates the coefficient in the heat transfer correlation through the application of the overall energy balance to the ensemble-cycle combustion and keeps them unchanged for all cycles. Both methods gave similar results, though the second procedure showed to be more physically consistent and in better agreement with the experimental results reported in the literature. The experimental matrix covered different engine speeds (n = 2000–4600 rpm), loads (bmep = 200–790 kPa), relative air-fuel ratios (RAFR = 0.80–1.60) and spark advances (SA ranging from 8 deg retard to 2 deg advance from MBT), for both CNG and gasoline operations, 100 consecutive in-cylinder pressure cycles were analyzed for each point in the test matrix and the sensitivity to cyclic variability of pressure, burn-rate and flame front position related parameters was analyzed. Main results showed that maximum pressure derivative, delay from SA of detected combustion start, NO exhaust concentration and maximum burning speed were the most sensitive parameters to cyclic variability. Strong correlations were found to hold between PFP and burned-gas temperature peak value, as well as between peak values of HRR and burning speed. On the contrary, some seemingly reasonable correlations were not assessed: for example, delay from SA of detected combustion start is related neither with PFP value nor with combustion duration. Finally, the results from mean cycle and cycle-resolved calculations were compared. Though they were usually in good agreement, in the case of NO emission and combustion interval calculation. cycle-resolved approach results in improved accuracy.
SAE International journal of engines, Mar 28, 2017
In the present work, different combustion control strategies have been experimentally tested in a... more In the present work, different combustion control strategies have been experimentally tested in a heavy-duty 3.0 L Euro VI diesel engine. In particular, closed-loop pressure-based and open-loop model-based techniques, able to perform a real-time control of the center of combustion (MFB50), have been compared with the standard map-based engine calibration in order to highlight their potentialities. In the pressure-based technique, the instantaneous measurement of in-cylinder pressure signal is performed by a pressure transducer, from which the MFB50 can be directly calculated and the start of the injection of the main pulse (SOImain) is set in a closed-loop control to reach the MFB50 target, while the model-based approach exploits a heat release rate predictive model to estimate the MFB50 value and sets the corresponding SOImain in an open-loop control. The experimental campaign involved both steady-state and transient tests. The three control techniques were compared in steady-state tests under various conditions, featuring standard as well as PCCI combustion mode, different kinds of fuels, a disturbance added to the pressure signals from in-cylinder transducers (to simulate the effect of an aged or low-cost pressure transducer) and an injector with a reduced mass flow rate mounted on one cylinder. The behavior of the three controls was tested in transient conditions as well, analyzing in particular fast load and speed ramps. The above mentioned testing conditions were performed to evaluate the robustness of the pressure-based and model-based techniques compared to standard calibration map-based control and their outcomes in terms of engine operation stability. The proposed real-time combustion control techniques provided fuel consumption and emissions in line with the conventional map-based control. In addition, they lead to an improvement in combustion stability, which can be an important issue especially when transient operations are considered or when non-conventional combustion modes, such as PCCI, are implemented.
SAE technical paper series, Apr 16, 2007
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, May 3, 2021
The paper investigates the effect of tire inflation pressure on the lateral dynamics of a passeng... more The paper investigates the effect of tire inflation pressure on the lateral dynamics of a passenger car, and presents a possible control-oriented methodology aimed at adapting tire pressure to the current vehicle loading condition targeting a reference characteristic. Starting from the tire characteristics at several inflation pressure levels, the paper investigates the effect of changing selectively tire pressure on each of the two axles, through theoretical calculation of the curvature gain based on the computation of the derivatives of stability, and compares the obtained sensitivity to the results of a multibody simulation model validated through on-track tests. Finally, the work presents a possible algorithm that could be implemented on-board vehicle ECU to provide, for the current loading condition of the vehicle, a tire pressure combination that targets a specific lateral dynamics characteristic. The algorithm is intended as part of the control logic of an intelligent Central Tire Inflation System (CTIS) able to adjust automatically tire pressure according to the actual vehicle working conditions.
Energies, Feb 19, 2021
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Energies, Oct 23, 2019
An experimental investigation has been carried out to compare the performance and emissions of a ... more An experimental investigation has been carried out to compare the performance and emissions of a low-compression-ratio Euro 5 diesel engine featuring high EGR rates, equipped with different injector technologies, i.e., solenoid, indirect-acting, and direct-acting piezoelectric. The comparisons, performed with reference to a state-of-the-art double fuel injection calibration, i.e., pilot-Main (pM), are presented in terms of engine-out exhaust emissions, combustion noise (CN), and fuel consumption, at low-medium engine speeds and loads. The differences in engine performance and emissions of the solenoidal, indirect-acting, and direct-acting piezoelectric injector setups have been found on the basis of experimental results to mainly depend on the specific features of their hydraulic circuits rather than on the considered injector driving system.
SAE technical paper series, Apr 11, 2005
ABSTRACT
Applied Energy, Oct 1, 2015
Thermal science and engineering progress, Aug 1, 2022
SAE International journal of passenger cars, Apr 3, 2018
SAE International Journal of Commercial Vehicles, Apr 3, 2018
SAE technical paper series, Apr 3, 2018
Energy Conversion and Management, Jul 1, 2015
In-cylinder pressure measurement and analysis has historically been a key tool for off-line combu... more In-cylinder pressure measurement and analysis has historically been a key tool for off-line combustion diagnosis in internal combustion engines, but online applications for real-time condition monitoring and combustion management have recently become popular. The present investigation presents and compares different low computing-cost in-cylinder pressure based methods for the analyses of the main features of combustion, that is, the start of combustion, the end of combustion and the crankshaft angle that responds to half of the overall burned mass. The instantaneous pressure in the combustion chamber has been used as an input datum for the described analytical procedures and it has been measured by means of a standard piezoelectric transducer. Traditional pressure-based techniques have been shown to be able to predict the burned mass fraction time history more accurately in spark ignition engines than in diesel engines. The most suitable pressure-based techniques for both spark ignition and compression ignition engines have been chosen on the basis of the available experimental data. Timefrequency analysis has also been applied to the analysis of diesel combustion, which is richer in events than spark ignited combustion. Time frequency algorithms for the calculation of the mean instantaneous frequency are computationally efficient, allow the main events of the diesel combustion to be identified and provide the greatest benefits in the presence of multiple injection events. These algorithms can be optimized and applied to onboard diagnostics tools designed for real control, but can also be used as an advanced validation tool for refined combustion models. The presented results on the pressure-based techniques, including a time frequency analysis, have been compared with the numerical outcomes from previously developed two-and three-zone thermodynamic combustion models.
SAE International journal of engines, Apr 20, 2009
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Papers by Stefano D’Ambrosio