Experimental Investigation and Numerical Simulation of Air Circulation in a Non-AC Bus Coach System

Document Type : Original Article


1 Department of Mechanical Engineering, School of Engineering and Technology, CHRIST (Deemed to be University), Bengaluru- 560076, Karnataka, India

2 Department of Mechanical Engineering, Atria Institute of Technology, Bengaluru- 560024, Karnataka, India

3 Department of Mathematics, School of Engineering and Technology, CHRIST (Deemed to be University), Bengaluru- 560076, Karnataka, India

4 Department of Mechanical Engineering, SJM Institute Technology, Chitradurga-577502, Karnataka, India

5 BLDEA’s V.P. Dr. P.G. Halakatti College of Engineering and Technology, Vijayapur-586103, Karnataka, India

6 Faculty of Engineering, Kuwait College of Science and Technology, Doha District, 7th Ring Road, 35004, Kuwait

7 Sanjeevan Engineering & Technology Institute, Sanjeevan Knowledge City, Panhala, Kolhapur, Maharastra, India


Air circulation plays a vital role in the comfort of passengers in a bus, being a non-AC bus without any aid from the air conditioning system. The circulation of air is utterly dependent on the design of the bus and the natural flow of air. However, optimize the flow of air inside the bus, a study on the design of the bus is needed. In this regard, experimental work was carried out to achieve uniform airflow by redesigning the coach into an aerodynamic shape. The openings are provided at the  leading edge of the bus to evaluate the best possibility for air to circulate in the bus. Three openings were provided at the leading edge of the bus, the first and second openings were mere openings, and the third opening was fitted with a roof vent providing three different geometric patterns to airflow. The initial boundary conditions were developed by considering that all windows and doors of the bus are closed. The scaling ratio of 1:20 was considered for modeling the bus. The experiments were conducted in the wind tunnel test rig. It was observed from the experimentation that the velocity of the air was considered to be the most influential parameter for the optimal air circulation. The velocities of  21.96 m/s and 22.68 m/s were obtained inside bus. The obtained experimental velocities were validated with results obtained by the Computational Fluid Dynamics (CFD). It was observed that a deviation of 5% for the given velocity of 20 m/s.


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