JOURNAL OF FACULTY OF ENGINEERING (UNIVERSITY OF TABRIZ)
Year:2005 | Volume:31 | Issue:1 (38) MECHANICS|Papers Count:6

The present work includes a quasi-dimensional combustion model to predict the combustion of direct injection dual fuel diesel engines by a detailed chemical kinetic model for gaseous fuel combustion. Chemical kinetic model consist of 325 reactions with 53 species (GRI3). Heat release rate of pilot fuel at this model is considered by two Wiebe functions. Predicted values of cylinder pressure for dual fuel operation show good agreement with corresponding previous experimental data.

Because of importance of damage identification by vibration parameters, there are several methods, among which, index method, because of its abilities, have important role in identifying damage in civil structures exact property of index method was unknown before. In this research, by using suitable model of beam with transverse crack on it we have shown that index method can be used on a simply supported beam to identify transverse crack on it, so we could study properties and strength of index method exactly. Through these studies, the important results have been driven, such as high indexes are made on nodes of beam and these indexes are moving toward crack by increasing the depth of crack. In experimental section of this project, the index methods have been used on simply supported aliminum beam with transverse notch on it by using modal analysis. Then experimental and theory results have been used for comparison purposes.

Air pollution is one of the complexity and important problems of populous and industrial cities in the world. Physical state of air-fuel mixture at inflammation instant is one of the main factors which can strongly influence on the performance as well as on the engine pollutants. Cold EGR technique and it’s entrance location into air manifold that have been recently proposed for controlling NO pollutant, can be considered as an important parameter to improve the characteristic of the physic of mixture. Since, in order to, elimination the EGR particles, optimum utilization of different species of EGR fluid and increasing it’s efficiency for reducing the engine pollutants, especially, NO pollutants, the clean EGR (refined) was studied on carbureted 1600cc paykan engine made by Iran Khodro Company. Experimental data, based on 18 modes of European standard showed that when refined EGR is added to air-fuel mixture from two different locations, it is caused to prevent from closing the EGR circuit pipes, and also compared with base engine, the reduction rates of UHC, CO, NO and bsfc were 5.9, 12.6, 59 and 8.8 percent respectively. In addition, reduction of power in the same condition and quantity of EGR, based on 70020 DIN standard, under full-load and 2500 rpm conditions was 2.2 percent.

Indirect measuring of tool wear without stopping the process is a purpose in machining. In this paper an intelligent system for on-line tool wear estimation in milling through measuring spindle motor current is proposed. For this the current of motor in different condition of machining (feed, depth of cut and rpm of tool) and wear were measured with practical experiments and the effects of milling tool wear on current of motor is analysed. Based on the results, a back propagation (bp) neural network is developed and trained. Using this network the tool wear could be estimated while machining in different conditions with measuring current of motor. This system could be used in controlling and monitoring of the machining process.

In this paper a numerical model has been introduced to solve the flow in open channels. The algorithm of this numerical model was developed in such a manner that prevents the instabilities, which are produced by the surface waves. With this model, the effects of shear stresses on the variations of the free surface elevation, especially in the regions of stronger shear stresses, were studied for three different open channels. Also the effect of Froud number increasing was studied. The numerical results showed that by increasing the Froud number the accuracy of the model was reduced. The details of numerical procedure were studied in a case, which convergence was failed.

The registration of data obtained from the sea wave characteristics has a crucial role in design, fabrication, and maintenance of offshore structures. Therefore, the fabrication of devices which aid the analysis in this respect is of prime interest. In this article, the basic of such a device (a sea wave impact tester) which was built in the University of Guilan is investigated. Several experiments has been carried out during years 1374-1379 in three base stations, namely, Nosrat-Abad (near to Astara), Anzali port, and Ramsar. The results analytically evaluated showed, the system in capable of recording the wave behavior in different situations. The analyzed results showed that the total behavior of sea wave in the south region of the Caspian Sea is independent of location. Also the results showed uniformity between the minimum and maximum sea wave force in the aforementioned areas. Finally a mathematical sea wave impact function model for the south of the Caspian Sea is presented.