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2 results on '"Hadi Khorand"'

1. Investigation of the efficiency of various reactive mufflers by noise reduction and transmission loss analyses

Author

Mahya Mohammadi, Seyed Esmail Razavi, Cyrus Aghanajafi, and Hadi Khorand

Subjects
Transmission loss, Noise reduction, Reactive muffler, k-ε model, Helmholtz equation, Technology, Electrical engineering. Electronics. Nuclear engineering, TK1-9971, Telecommunication, TK5101-6720
Abstract

Transmission loss and noise reduction of reactive mufflers are determined by linear acoustic theory and unsteady flow field study, respectively. The effects of extending the inlet tube of the muffler, adding holes to the extension, and the number of holes on both transmission loss and noise reduction are investigated. In noise reduction analysis, the Navier-Stokes equations and k-ε model are used to study the unsteady turbulent flow. Helmholtz equation is solved for transmission loss analysis. The present study is validated with experimental data. Numerical results show a rise in noise reduction by extending the inlet tube of the muffler and increasing its length. Moreover, the extended mufflers cause more transmission loss and broadband behavior at some frequencies due to the resonances. According to the results, different points of view in the investigation of acoustic attenuation performance of mufflers can be helpful to understand more and better about the effect of geometrical parameters.

Published
2018
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2. Combustion and emission characteristics of biomass derived biofuel, premixed in a diesel engine: A CFD study

Author

Hassan Mohammadi, Mehdi Vahabzadeh Bozorg, Yaning Zhang, Asgar Asadi, Hadi Khorand, Zhenhua Rui, and Mohammad Hossein Doranehgard

Subjects
Biodiesel, Materials science, 060102 archaeology, Renewable Energy, Sustainability and the Environment, 020209 energy, Biomass, 06 humanities and the arts, 02 engineering and technology, Combustion, Diesel engine, medicine.disease_cause, Soot, Diesel fuel, Chemical engineering, Biofuel, 0202 electrical engineering, electronic engineering, information engineering, medicine, 0601 history and archaeology, NOx
Abstract

In this study, the effect of biodiesel premixing on emission, combustion characteristics and engine performance was numerically investigated via AVL Fire. In order to confirm the validity of the study, combustion inside the chamber was simulated in a condition in which the fuel was pure diesel, and the results were compared with results presented in other work. Engine performance parameters and emissions were in a very good agreement with those reported in other research works. After the validity of the engine achieved, in the first phase of the study, pure diesel fuel and the mixture of diesel-biodiesel blends were injected to the chamber without premixing. In the next phase, pure biodiesel and biodiesel blends were premixed within the chamber and the effect of premixing on the interesting parameters was investigated. Results showed that premixing biodiesel leads to a reduction in the soot emission and increment in the NOx emission. In addition to this, using pure diesel as the main injected fuel and pure biodiesel as the premixed fuel decreased soot emission considerably. Besides, unlike biodiesel blends, it did not increase NOx emission considerably.

Published
2019
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