Showing 24 results for Performance
Dr Javad Zareei, Abbas Rohani,
Volume 11, Issue 2 (6-2021)
Abstract
Diesel engines are the most trusted sources in the transportation industry. They are also widely used in the urban transportation system. Most pollutants are related to these engines. Therefore, it is important to increase the performance and reduce exhaust emissions of these engines. Alternative fuels are key to meeting upcoming targets.
An experimental and numerical study was performed to investigate the effect of diesel fuel and hydrogen addition to diesel fuel from 0 to 30% on performance and exhaust emissions. Also in this research for changing diesel fuel, an indirect injection engine converted to direct injection engine. The simulation study was conducted by Star cd codes and experimental investigation was carried out on a diesel engine (Perkins 1103A-33TG1), three- cylinders, and four-stroke with maximum engine power 72.3hp at 1800 rpm. The results from this study showed that the increase of hydrogen to diesel fuel improves the thermal efficiency, resulting in lower specific fuel consumption. Also, the results showed that adding hydrogen until 30%, the cylinder pressure increase by about 9% and occurred the delay of peak pressure about 8 degrees of a crank angle compared to diesel fuel. The other obtained results in emission with 30%H2+Diesel showed the soot emission reduced 11.3%, HC and CO reduced nearly 36%, but NOx increased by about 8.3% due to high combustion temperature.
Hossein Chehardoli,
Volume 12, Issue 2 (6-2022)
Abstract
The adaptive size-independent consensus problem of uni-directional (UD) and bi-directional (BD) decentralized large-scale vehicle convoys with uncertain dynamics has been investigated in this research work. The constant distance plan (CDP) is employed to adjust the distances between successive vehicles. We assume that only relative displacement information between adjacent vehicles is accessible (partial measurement) and other information such as relative velocity and acceleration are not provided. The stability of the convoy can be performed by the analysis of each couple of consecutive vehicles. The main objective is to design an adaptive size-independent control protocol maintaining internal and string stability based on CDP with only partial measurement. Appropriate adaptive rules are derived to estimate the uncertain dynamics by utilizing only relative displacement. It will be proved that the presented adaptive protocol assures both internal stability (asymptotic stability of closed-loop convoy) and string stability (tracking error attenuation) of large-scale decentralized UD and BD convoys under the CDP. Simulations demonstrate the efficiency of the presented control framework.
Hamidreza Ebrahimi, Mohammadhassan Shojaeifard, Salman Ebrahimi-Nejad,
Volume 13, Issue 2 (6-2023)
Abstract
The present study aims to optimize a two-chamber muffler’s geometry and improve its acoustic performance. Mufflers with a circular cross-section are used in this study and then underwent the vibroacoustic analysis using COMSOL Multiphysics software. Several geometries, including a reference model and new ones, are designed and their geometry is optimized by Parametric and grid optimization methods, which are the software’s optimization methods. First, the reference paper is validated to ensure the simulation produces the least error. The results obtained in this study have a good match with those of the reference. Then, by changing dimensions such as length, diameter, and inner design of the mufflers, the best geometry in terms of transmission loss and bandwidth was selected and compared with the results acquired by the reference model. It was found that the acoustic performance of the optimized design (two-chamber muffler with four inner tubes) outperforms the model used in the reference. That is, the results indicate that the optimized design is able to attenuate sound up to 78dB in the range of 0 to 500Hz, 45dB higher than that of the conventional model. Further, the muffler’s weight is reduced by a quarter, using a 0.9mm thickness.
Hojjat Saberinejad,
Volume 15, Issue 1 (3-2025)
Abstract
One of the main challenges in designing a vehicle's cooling system, particularly the radiator, is not considering the non-uniform airflow distribution in the radiator's characteristic performance graphs. In this study, a three-dimensional numerical analysis of the airflow passing through a QUIK vehicle and the effect of the cooling system's placement relative to the vehicle's grille in five different cases was conducted. The effect of non-uniform airflow distribution on related radiator parameters such as the Darcy number, particle diameter, and inertial term was examined. The results indicate that the optimal placement range of the vehicle's cooling system for appropriate cooling performance is very limited. Additionally, non-uniform air velocity distribution plays a significant role in the radiator pressure drop. The inertial term is more significant in non-uniform flow conditions. For larger Forchheimer numbers, the change in radiator pressure drop for uniform compared to non-uniform flow distributions is about 22%.
