جستجوی مقالات مرتبط با کلیدواژه « IC engine » در نشریات گروه « مکانیک »

This paper is about the application of instantaneous angular speed (IAS) signal in a 3-liter six-cylinder gasoline engine. The study is in continuation of former work in which a measurement system was developed for this signal on a rotating machine. The future trend of the research is to measure IAS in an I.C. engine. Therefore, the objective of the current work is to provide a verified software tool which can run simulated experiments with IAS signal output under healthy/faulty conditions. An engine model with detailed crankshaft elements is established in the GT-SUITE[1]</sup> software. Under the GT-SUITE environment, IAS signal output is obtained through simulated experiments. In order to validate the tool, the first torsional natural frequency of the crankshaft obtained from frequency analysis on the IAS signal is compared with the result of modal analysis on the crankshaft structure using the F.E. method. Also, the value is compared with the prediction from the GT CrankAnalysis module. A good match is found, which shows the validity of the developed software tool. Faulty condition of misfiring in one cylinder is simulated using this tool, and expected observations on the IAS output signal are verified to address the future trend of the research using the developed tool in this study.

In this paper, to address the problem of using displacement sensors in measuring the transverse vibration of engine accessory belt, a novel non-contact method based on machine vision and Mask-RCNN model is proposed. Mask-RCNN model was trained using the videos captured by a high speed camera. The results showed that RCNN model had an accuracy of 93% in detection of the accessory belt during the test. Afterward, the belt curve was obtained by a polynomial regression to obtain its performance parameters. The results showed that normal vibration of the center of the belt was in the range of 2 to 3 mm, but the maximum vibration was 8.7 mm and happened in the engine speed of 4200 rpm. Also, vibration frequency of the belt was obtained 124 Hz. Moreover, the minimum belt oscillation occurred at the beginning point of the belt on the TVD pulley, whereas the maximum oscillation occurred at a point close to the center of the belt at a distance of 16 mm from it. The results show that the proposed method can effectively be used for determination of the transvers vibration of the engine accessory belts, because despite the precise measurement of the belt vibration at any point, can provide the instantaneous position curve of all belt points and the equation of the belt curve at any moment. Useful information such as the belt point having the maximum vibration, belt slope, vibration frequency and scatter band of the belt vibration can be obtained as well.

In this article, an intelligent system is introduced in order to detection and classification of some common mechanical faults of an engine alternator based on the frequency analysis of vibration signals. For this purpose, firstly the vibration signals of an alternator under four conditions, including healthy, bearing corrosion, cracked rotor and unbalanced excited shaft, were captured by an accelerometer. Time-domain signals were then transformed into frequency-domain with the aid of FFT. At the next step, power spectral density (PSD) method was used for the secondary frequency signal processing level. Afterward, in data mining step, twelve statistical features were extracted from the PSD values of the signals, which were fed as the input data into the ANN classifier to detect and classify the alternator faults. The results indicate that the proposed method has the capable of detecting the different alternator faults with an accuracy higher than 92%.

Nobody escapes the importance of the air/fuel mixture preparation in internal combustion engines, whatever is the thermodynamic cycle they work on and the adopted fuel. The short time between the fueling and the start of the combustion is crucial for the best mixture formation and its burning for energy optimization and the pollutant production. The always stringent vehicle emissions rules led engine research toward the use of high-pressures and direct-injection systems for allowing a best atomization/vaporization of the fuel while, as drawback, the downsizing of the combustion system results in increasing of fuel impact on the combustion chamber and cylinder line with HC and particulate matter increase at the exhaust. A complete description of the injected fuel, its spread in the chamber with primary and secondary breakups, the vaporization, the mixture with the air and the combustion are of basic importance to govern the process and help new design architectures. Optical characterization has shown it’s powerful in describing these processes without interfering with their evolution both in stationary and reciprocating devices. Imaging and spectroscopic techniques allow us to follow the physic-chemical transformations of the initial bulk of fuel in the mixture, production of primary and secondary species and individuate the potential sites of pollutant production. Furthermore, the results constitute a data set for initializing and calibrating numerical codes for provisional, results and behavior of diverse injecting systems and at different ambient conditions, and last but not the least inside the engine. In this paper, a tracking shot of optical techniques adopted to depict the fuel spread in a quiescent optical accessible vessel at engine-like conditions is reported for practices of fuel direct injection in engines.

Porous media has interesting features in compared with free flame combustion due to the extended of the lean flammability limits and lower emissions. Advanced new generation of internal combustion (IC) engines are expected to have far better emissions levels both gaseous and particulate matter, at the same time having far lower fuel consumption on a wide range of operating condition. These criteria could be improved having a homogeneous combustion process in an engine. Present work considers simulation of direct fuel injection in an IC engine equipped with a chemically inert porous medium (PM), having cylindrical geometry that is installed in cylinder head to homogenize and stabilize the combustion process. A numerical study of a 3D model, PM engine is carried out using a modified version of the KIVA-3V code. Since there is not any published material for PM-engines in literature, the numerical results for combustion waves propagation within PM are compared with experimental data available in the literature for a lean mixture of air and methane under filtration in packed bed, the accuracy of results are very promising. For PM-engine simulation the methane fuel is injected directly through a hot PM which is mounted in cylinder head. Therefore volumetric combustion occurs as a result within PM and in-cylinder. The effects of injection timing on mixture formation, pressure and temperature distribution in both phases of PM and incylinder fluid together with combustion emissions such as CO and NO are studied in detail for an important part of the cycle.