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Fluctuations in the Energetic Properties of a Spark-Ignition Engine Model with Variability
Instituto de Ingeniería Mecánica y Producción Industrial, Universidad de la República, Montevideo 11300, Uruguay
Departamento de Física Aplicada, Universidad de Salamanca, Salamanca 37008, Spain
Departamento de Física Aplicada and IUFFYM, Universidad de Salamanca, Salamanca 37008, Spain
Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas, Instituto Politécnico Nacional, Av. IPN 2580, L. Ticomán, Mexico D.F. 07340, Mexico
Departamento de Física, Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Edif. No. 9 U.P. Zacatenco, Mexico D. F. 07738, Mexico
* Author to whom correspondence should be addressed.
Received: 8 June 2013; in revised form: 30 July 2013 / Accepted: 13 August 2013 / Published: 19 August 2013
Abstract: We study the energetic functions obtained in a simulated spark-ignited engine that incorporates cyclic variability through a quasi-dimensional combustion model. Our analyses are focused on the effects of the fuel-air equivalence ratio of the mixture simultaneously over the cycle-to-cycle fluctuations of heat release (QR) and the performance outputs, such as the power (P) and the efficiency (QR). We explore the fluctuant behavior for QR, P and n related to random variations of the basic physical parameters in an entrainment or eddy-burning combustion model. P and n show triangle shaped first return maps, while QR exhibits a structured map, especially at intermediated fuel-air ratios. Structure disappears to a considerable extent in the case of heat release and close-to-stoichiometry fuel-air ratios. By analyzing the fractal dimension to explore the presence of correlations at different scales, we find that whereas QR displays short-range correlations for intermediate values of the fuel ratio, both P and n are characterized by a single scaling exponent, denoting irregular fluctuations. A novel noisy loop-shaped P vs. n plot for a large number of engine cycles is obtained. This plot, which evidences different levels of irreversibilities as the fuel ratio changes, becomes the observed loop P vs. n curve when fluctuations are disregarded, and thus, only the mean values for efficiency and power are considered.
Keywords: spark ignition engine; quasi-dimensional simulations; cycle-to-cycle variability; energetics
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Curto-Risso, P.L.; Medina, A.; Calvo-Hernández, A.; Guzmán-Vargas, L.; Angulo-Brown, F. Fluctuations in the Energetic Properties of a Spark-Ignition Engine Model with Variability. Entropy 2013, 15, 3277-3296.
Curto-Risso PL, Medina A, Calvo-Hernández A, Guzmán-Vargas L, Angulo-Brown F. Fluctuations in the Energetic Properties of a Spark-Ignition Engine Model with Variability. Entropy. 2013; 15(8):3277-3296.
Curto-Risso, Pedro L.; Medina, Alejandro; Calvo-Hernández, Antonio; Guzmán-Vargas, Lev; Angulo-Brown, Fernando. 2013. "Fluctuations in the Energetic Properties of a Spark-Ignition Engine Model with Variability." Entropy 15, no. 8: 3277-3296.