Title: Approach to Control the in Cab Noise without Affecting Passenger Comfort in AC Midi Buses
text: This paper discusses various fruitful iterations / experiments performed to reduce air flow induced noise without compromising on total air flow requirement for thermal comfort and ways to avoid heat ingress inside the bus. Also the paper discusses the devised process for noise reduction through front loading of computer aided engineering and computational fluid dynamics analysis. Air conditioning buses in light commercial vehicle (LCV) segment is growing market in India, especially for applications like staff pick-up and drop, school applications and private fleet owners. The air-conditioning system is typically mounted on bus roof top and located laterally and longitudinally at center. It is an easiest and most feasible way to package air conditioning system to cater the large passenger space (32 to 40 seats) with the conditioned air. This makes air conditioning duct design simple and commercially viable. Most of the LCV buses are with front engine configuration which adds more heat and noise to driver and passenger compartment, this demands for isolation of driver's area from passenger area by means of partition in between. In case of buses without partition engine noise is more dominant, but in case of buses with partition, blower noise of roof mounted AC system is more perceivable in passenger area. The larger glass area, limitation on glass tint percentage and mandate for not to use curtain added more challenges in front of thermal engineer to device effective cabin cooling system to cater huge heat load and achieve required human comfort.