ARTICLE INFO In this research study, alumina nanoparticles (80 and 120 ppm) were prepared and added as additive to the diesel fuel. Effect of these blended fuels was investigated on the performance and exhaust emission of six cylinders, four-stroke diesel engine and the results were compared with the neat diesel fuel. Experimental results reveal that by using of nano-fuels and increase of nanoparticles concentration at diesel fuel increased engine performance variables including engine power and torque output up to 2% and brake specific fuel consumption (BSFC) was decreased 6.01% compared to the neat diesel fuel. Also results proved by increase of nanoparticles concentration at diesel fuel CO and HC emission decreased 13.1% and 23.4% compared to pure diesel fuel respectively. Moreover, CO2 and NOx emission increased 29.5% and 33.3% compared to pure diesel fuel respectively. Therefore, the results showed that alumina nanoparticle additives in diesel fuel increased engine performance and reduced exhaust emission of diesel engine and it can be used as an alternative and environmentally friendly fuel in CI engines. © Iranian Society of Engine (ISE), all rights reserved. Article history: Received: 14 September 2020 Accepted: 1 November 2020
ARTICLE INFO In this paper, the influence of the equivalence ratio on combustion characteristics has been examined by considering 16 different operating conditions. The fuel used in this research is gasoline and the ignition takes place in two stages. The first stage of combustion is due to low-temperature reaction heat release (LTRHR), and the second stage is related to the high-temperature reaction heat release (HTRHR). The three-dimensional computational fluid dynamics (3DCFD) with chemical kinetics has been chosen as the numerical method. In all of the studied operating conditions, the 3D-CFD simulations were able to see the combustion properly and the increase of maximum pressure and maximum rate of heat release (ROHRmax) with the rise of the equivalence ratio was properly observed. Also, by increasing the equivalence ratio, the 3D-CFD model show advanced maximum pressure and ROHRmax but mistakenly predicted the start of LTRHR more delayed, while the HTRHR was properly predicted. © Iranian Society of Engine (ISE), all rights reserved. Article history: Received: 5 December 2020 Accepted: 16 January 2021
ARTICLE INFO In this article, an intelligent system is introduced to the 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 signal of an alternator under four conditions, including healthy, bearing corrosion, cracked rotor, and the unbalanced excited shaft was captured by an accelerometer. Timedomain signals were then transformed into frequency-domain with the aid of FFT. At the next step, the power spectral density (PSD) method was used for the second frequency signal processing level. Afterward, in the 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 capability of detecting the different alternator faults with an accuracy higher than 92%. © Iranian Society of Engine (ISE), all rights reserved. Article history: Received: 8 December 2019 Accepted: 20 May 2020
ARTICLE INFO The effect of perimeter fins on the thermal stress and low cycle fatigue life (LCF) of exhaust manifolds was investigated. For doing this, Solidworks software was used to model the exhaust manifolds. Three Perimeter fins with 4 mm thickness were attached to the modified exhaust manifolds outlet section. Then ANSYS Workbench software was used to determine stress and fatigue life based on Morrow and Smith-Watson-Topper (SWT) approaches. Finally, the improvement of the low cycle fatigue life was studied. The temperature-dependent of material parameters was considered to increase the accuracy of LCF life results. The results of finite element analysis (FEA) uncovered the fact that perimeter fins reduce the temperature distribution in the exhaust manifolds about 32.54°C. As a result, the exhaust manifolds tolerates lower temperature, and fatigue life will increase. The results of thermo-mechanical analysis indicated that the stress in the modified exhaust manifolds decreased approximately 22MPa for the sake of depletion of temperature gradient, which can lead to higher fatigue lifetime. The results of LCF showed that the number of cycles of failure for modified exhaust manifold is approximately 55% higher than the results obtained from the original exhaust manifolds. © Iranian Society of Engine (ISE), all rights reserved. Article history: Received: 6 July 2020 Accepted: 14 September 2020
ARTICLE INFO The effect of the temperature on exhaust manifold modal analysis was investigated in this study. For doing this, Solidworks software was used to model the exhaust manifolds. Then the modal analysis was performed to get the natural frequencies in Abaqus software. Finally, the modal analysis that considers the temperature effect was done. The study of structural dynamics is essential for understanding and evaluating the performance of any engineering product. The determination of the dynamic characteristics of automotive structures has become an extremely important issue in the automobile industry. Modal Analysis is currently one of the key technologies in structural dynamics analysis. The temperature-dependent of material parameters was considered to increase the accuracy of finite element analysis (FEA) results. The results of FEA proved a very good agreement between temperature distribution and thermal analysis results, carried out in references. The frequency and vibration mode between cold modal and thermal modal were compared. The results showed that temperature has a great influence on the exhaust manifold mode and it is very valuable to product design. The results of the modal analysis proved that the maximum strain energy density and total strain energy exist in the confluence area. The results of the finite element analysis correspond with the experimental tests, carried out in references, and illustrate the exhaust manifold cracked in this region. The obtained FEA results show that gas pressure is effective on the modal analysis and must be considered in the modal analysis of exhaust manifold. © Iranian Society of Engine (ISE), all rights reserved. Article history: Received: 30 January 2020 Accepted: 20 May 2020
