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An analytical model, which takes care of thermal interactions of human body with surroundings via basic heat transfer modes like conduction, convection, radiation and evaporation, is compiled. The analytical model takes measurable inputs from surroundings and specific human parameters. Using these parameters a quick calculation entailing all heat transfer modes ensues in net heat exchange of human body with surroundings. Its magnitude and direction decides the qualitative indication of thermal comfort of concerned human being. The present model is scaled on actual human beings by noting the subjective assessment in comfortable as well as uncomfortable surroundings. As a part of validation, it is implemented in an actual Climatic Wind Tunnel Heater test, where temperatures and other parameters on different parts of the body are noted down and fed to the model as input. Output of the equation is then compared with the subjective assessment of human beings.

In cold climatic regions (25°C below zero) thermal comfort inside vehicle cabin plays a vital role for safety of driver and crew members. This comfortable and safe environment can be achieved either by utilizing available heat of engine coolant in conjunction with optimized in cab air circulation or by deploying more costly options such as auxiliary heaters, e.g., Fuel Fired, Positive Temperature Coefficient heaters. The typical vehicle cabin heating system effectiveness depends on optimized warm/hot air discharge through instrument panel and foot vents, air directivity to occupant's chest and foot zones and overall air flow distribution inside the vehicle cabin. On engine side it depends on engine coolant warm up and flow rate, coolant pipe routing, coolant leakage through engine thermostat and heater core construction and capacity.

Vehicle incab booming perception, a low frequency response of the structure to the various excitations presents a challenging task for the NVH engineers. The excitation to the structure causing boom can either be power train induced, depending upon the number of cylinders or the road inputs, while transfer paths for the excitation is mainly through the power train mounts or the suspension attachments to the body. The body responds to those input excitations by virtue of the dynamic behavior mainly governed by its modal characteristics. This paper explains in detail an integrated approach, of both experimental and numerical techniques devised to investigate the mechanism for boom noise generation. It is therefore important, to understand the modal behavior of the structure. The modal characteristics from the structural modal test enable to locate the natural frequencies and mode shapes of the body, which are likely to get excited due to the operating excitations.

The vehicle Heating, Ventilation and Air conditioning (HVAC) system is designed to meet both the safety and thermal comfort requirements of the passengers inside the cabin. The thermal comfort requirement, however, is highly subjective and is usually met objectively by carrying out time dependent mapping of parameters like the velocity and temperature at various in-cabin locations. These target parameters are simulated for the vehicle interior for a case of hot soaking and its subsequent cool-down to test the efficacy of the AC system. Typically, AC performance is judged by air temperature at passenger locations, thermal comfort estimation along with time to reach comfortable condition for human. Simulating long transient vehicle cabin for thermal comfort evaluation is computationally expensive and involves complex cabin material modelling.

The goal of reducing fuel consumption and CO2-Emission is leading to turbo-charged combustion engines that deliver high torque at low speeds (down speeding). To meet NVH requirements damper technologies such as DMF (Dual Mass Flywheel) are established, leading to reduced space for the clutch system. Specific measures need to be considered if switching over from SMF (Single Mass Flywheel) to DMF [8]. Doing so has an impact on thermal behavior of the clutch system, for example due to reduced and different distribution of thermal masses and heat transfer to the surroundings. Taking these trends into account, clutch systems within vehicle powertrains are facing challenges to meet requirements e.g. clutch life, cost targets and space limitation. The clutch development process must also ensure delivery of a clutch system that meets requirements taking boundary conditions such as load cycles and driver behavior into account.

Reduction of NOx (Oxides of Nitrogen) and particulates from engine exhaust is one of the prime considerations in current research and development in automotive industry. The present paper describes the combustion optimization done on a four cylinder, 4 liter DI diesel engine to meet stringent Euro-III emission norms. The engine FIE (Fuel Injection Equipment) and injector geometry was optimized for performance and emission. Smoke measurements were considered as indicative of soot, to predict particulate emissions. This was done to simplify the overall process and save development time. It was concluded that by combining the flexibility of electronically controlled fuel injection begin, with improved nozzle technologies, with higher spray velocities and spray penetration, a considerable reduction in NOx and particulate emissions can be achieved. This can serve as a low cost solution, without any exhaust after-treatment systems.

When an automobile negotiates a flooded region, water is splashed due to the rotational motion of the wheels. This water enters the air intake system of the turbocharged intercooled engine along with air and can pass through the turbocharger, intercooler and enter the engine. As water is an incompressible fluid, the piston cannot compress water inside the cylinder which leads to connecting rod bending and severe engine damage. This paper explains how the same has been resolved using CFD methodology and proposes the re-designed model of mud cover as a solution to this problem. The entire process has been streamlined and major time and cost reduction achieved by using simulation for optimization. The simulated results have been validated by extensive trials for correlation and outdoor tests for durability. Same analysis technique is used as a template to modify the air intake system.

In recent times, CFD (Computational Fluid Dynamics) simulation tools have been deployed by automotive OEMs for investigating Climate Control applications. In automotive vehicles, one such critical application is designing defroster nozzles with least flow resistance to carry hot air from HVAC (Heating Ventilation and Air Conditioning) unit and dispersing it onto the windscreen and side glasses to clear mist and ice. Clearance of windscreen and side window glass has a high importance for safe driving as mist and ice formation affects driver's visibility and comfort while driving in humid and snowy conditions respectively. In the present study, a half cabin model of the vehicle is prepared using commercial software package ICEM CFD as grid generation tool and CFD analysis is carried out using commercial software package FLUENT 6.3 to optimize the air flow distribution over the windscreen and then to predict defrost performance prior to full scale climatic wind tunnel tests.

DFSS is a disciplined problem prevention approach which helps in achieving the most optimum design solution and provides improved and cost effective quality products. This paper presents the implementation of DFSS method to design a distinctive cooling system where engine is mounted in the rear and radiator is mounted in the front of the car. In automobile design, a rear-engine design layout places the engine at the rear of the vehicle. This layout is mainly found in small, entry level cars and light commercial vehicles chosen for three reasons - packaging, traction, and ease of manufacturing. In conventional Passenger cars, a radiator is located close to the engine for simple packaging and efficient thermal management. This paper is about designing a distinctive cooling system of a car having rear mounted engine and front mounted radiator.

Small goods carrier and passenger vehicles powered by Naturally Aspirated (NA) Direct Injection (DI) diesel engines are popular in Indian automobile market. However, they suffer from inherently high radiated noise and poorly perceived sound quality. This paper documents the steps taken to reduce the radiated noise level from such an engine through structural modifications of major noise radiating components identified in the sound power analysis. The work is summarized as follows; Baseline radiated noise measurements of power train and identification of major noise sources through sound intensity mapping and noise source ranking (NSR) in an Engine Noise Test Cell (ENTC) Design modifications for identified major sources in engine structure Vehicle level assessment of the radiated noise in a Vehicle Semi-Anechoic Chamber (VSAC) for all the design modifications. A reduction of 7 dB at hot idle and 4 - 8 dB in loaded speed sweep conditions was observed with the recommended modifications.

The power output of an internal combustion engine is directly proportional to the amount of air that can be forced into the cylinder per cycle and the amount of fuel that can be burned efficiently. The amount of air is most effectively increased by means of a mechanical supercharger. The purpose of this paper is attempting the non mechanical supercharging ways (Supercharging by means of gas dynamic effects) for naturally aspirated (NA) diesel engines and understanding in a better way the induction gas dynamics and its influence on engine performance characteristics. Wave dynamics in the intake system has strong influence on the performance of naturally aspirated internal combustion (IC) engines. This paper presents an application of Helmholtz resonator in the induction system of the naturally aspirated diesel engine to improve the engine breathing efficiency (volumetric efficiency).

The modern trend of engine downsizing for CO₂ reduction coupled with stringent emission norms compel the engine air inlet system to outperform the conventional designs. Modern turbo diesel engine air inlet system handles higher & higher air flow, boost pressure and temperature. Air inlet system ducting designs have become complex due to oil particles (received through PCV system), engine movement and isolation for NVH. Air inlet ducting failures; like oil mist leakage through joints and seepage through hose wall cause high engine oil consumption and most predominantly environment damage. Also to some extent boost leakage in certain operating conditions. These failures reduce the reliability and performance of engine in certain conditions. This paper discusses design and development of cost-effective non-permeable and leak-proof hose-piping system for turbocharged diesel engine where PCV system was connected to air inlet system.

Integrating safety features may lead to changes in vehicle interior component designs. Considering this complexity, design guidelines have to take care of aspects which may help in package feasibility studies that consider systems performance requirements. Occupant restraints systems for protection in side crashes generally comprise of Side Airbag (SAB) and Curtain Airbag (IC). These components have to be integrated considering design and styling aspects of interior trims, seat contours and body structure for performance efficient package definition. In side crashes, occupant injury risk increases due to hard contact with intruding structure. This risk could be minimized by cushioning the occupant contact through provision of SAB and Inflatable IC. This paper explains the methodology for deciding the package definitions using Knowlwdge Based Engineering (KBE) tools.

This paper deals with the problem of cyclic irregularities during idling in relation with port to port fuel delivery variation of rotary Fuel Injection Pump (FIP) for a diesel engine. The relation is demonstrated on a two cylinder engine, where problem of high cyclic irregularities was observed for which the root cause was identified as the fuel delivery variation from the FIP, which was later taken up for the improvements in the design. This paper discusses the technical approach used in identifying the root cause for the high cyclic irregularities and the solution of the problem. It is demonstrated how angular acceleration of the crankshaft free end can be used to diagnose the non-uniformity of combustion in different cylinders which leads to higher cyclic irregularities. The solution discusses the improvements done in the hydraulic passages of the head and rotor of the FIP for line to line fuel delivery variation control.

The paper describes a first-of-its-kind attempt of authors to develop an intake manifold - combined with - rocker cover (IMCRC) in sheet molding compound (SMC) for 3 L and 4 L direct injection diesel engines with power ratings 75 kW and 92 kW respectively. The objective was to reduce overall engine weight, noise and cost. The intake manifold is designed to withstand absolute boost pressures of more than 2 bar, temperature in the range of 160 °C. and capable of carrying load of directly attached components such as an air intake pipe. It is worth to note that the designed SMC component always remains in the vicinity of the exhaust manifold by virtue of base engine layout constraint. The development if successful can expand the horizon of SMC in diesel engine application.

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.

This paper focuses on factors that enhance energy efficiency of air conditioning system on mid-sized, standard and premium buses with engine power from 125 to 280 HP. It covers aspects like light weighting of roof air conditioning system, usage of optimized ducting system with minimal resistance to blowers, deployment of rotary scroll compressor with fast idle control in place of reciprocating piston compressor. The scope of this paper covers AC compressors driven by main engine of vehicle/ bus, study related to auxiliary/donkey engine driven AC compressor is not considered. Context- In order to enhance fuel efficiency in buses an energy efficient air conditioning system should be deployed. This will lead to reduced parasitic load on the engine and translate into direct fuel saving.

Better ride and comfort, enhanced safety, reliability and durability, lower running cost as well as cost of ownership continue to be challenges for automotive OEMs. Higher fuel efficiency is considered as USP not only for lower running cost but also is hygiene factor from sustainability point of view. This has necessitated the need for Augmenting Light weighting horizon in automotive OEMs. Augmenting this leads to invention of innovative materials and processes for emerging cost competitive market. This paper focuses on technology efforts towards augmenting light weighting Horizon in Automotive. Light weighting concepts being explored by OEMs with the help of automotive component manufacturers from Powertrain - Engines & Transmission, Chassis and Suspension are discussed.

The objective of the work presented in this paper is to provide an overall CFD evaluation and optimization study of cabin climate control of air-conditioned (AC) city buses. Providing passengers with a comfortable experience is one of the focal point of any bus manufacturer. However, detailed evaluation through testing alone is difficult and not possible during vehicle development. With increasing travel needs and continuous focus on improving passenger experience, CFD supplemented by testing plays an important role in assessing the cabin comfort. The focus of the study is to evaluate the effect of size, shape and number of free-flow and overhead vents on flow distribution inside the cabin. Numerical simulations were carried out using a commercially available CFD code, Fluent®. Realizable k - ε RANS turbulence model was used to model turbulence. Airflow results from numerical simulation were compared with the testing results to evaluate the reliability.

An emissions, combustion noise and performance study were conducted to explore the effects of two different multiple injections strategies on emissions, combustion noise and performances without altering EGR %. The experiments were done on a six cylinder inline CRDI diesel production engine. The aim of this study is to improve performances (brake specific fuel consumption [BSFC], torque) and combustion noise (reduction) using multiple injection strategies without violating emission regulations. The other objective of this carried-out analysis is to examine the influence of different operating parameters (Speed and Load) and main injection timing combined, on same multiple injection strategies (Pilot- main – after {PMA}and Early - pilot- main –after {EPMA}) by means of analyzing emissions/soot, combustion noise and performances data.