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Mejora de una herramienta de diagnóstico de la combustión a partir de la presión instantánea en cámara mediante la incorporación de un modelo de tumble
| Content Provider | Semantic Scholar |
|---|---|
| Author | Torres, Daniel Verdú |
| Copyright Year | 2017 |
| Abstract | This project represents the memory of a Master's Thesis as the last step to complete the Master of Industrial Engineering. Throughout the different sections that form the document, it briefly describes the work done in the last six months, as well as the conclusions and results obtained after the execution of the project. It also explains the problems that have appeared and the solutions adopted. The purpose of the report is to propose a new theoretical model that allows to describe the influence of the tumble gas movement inside the chamber in the heat transfer that occurs and improve what is currently implemented in the CALMEC engine diagnostic’s tool. Since the gas enters the chamber during the intake phase, a more or less defined structure begins to develop. As the cycle progresses, the tumble movement becomes more intense. During the compression phase, its decay begins, the movement pattern disappears a few degrees before the TDC. Unlike the tumble movement, the swirl reaches its maximum around the TDC. Therefore, another model is needed to describe the heat transfer in the tumble case. The proposed model is a modification of the original equation proposed by Woschni for the swirl case. In the Woschni model, the heat transfer coefficient depends on the velocity of the gas, which in turn depends on a term proportional to the average speed of the piston, a term due to combustion and a last term referring to the tangential velocity of the gas due to the swirl movement. The equation also includes some constants called Cw1, Cw2 and C2 that weight the influence of each of the terms and whose objective is to adjust the theoretical model to the specific engine tested. In the case of the proposed model, the tangential gas velocity is the product of a mean tangential velocity and a mathematical function that represents the behaviour of the tumble phenomenon as a function of the crankshaft angle. The mean tangential velocity is proportional to the engine speed and the mean tumble ratio. After implementing the model and analysing the results provided by the model in a motoring test, it can be concluded that the model is accurately adjusted to the heat predicted by the method of the polytrophic exponent regardless of the engine speed. Finally, two sensitivity studies of the proposed model have been carried out taking into account uncertainties in some of the input variables or in the determination of some of the parameters of the model; one of them before performing the fitting process and the other, after fitting the model constants to the engine tested. In the first case, the motor is sensitive to errors in the definition of some of the parameters that govern the model, while after adjusting the constants of the model, the model shows to be robust against any perturbation. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://riunet.upv.es/bitstream/handle/10251/81067/04628120Z_TFG_14919250446171309387839868989059.pdf?isAllowed=y&sequence=2 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
