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There are several physico-chemical processes which affect diesel combustion. Among them the processes occurring prior to the ignition have significant influence on the combustion and emission characteristics of direct injection diesel engine. The premixed phase combustion appearing between the ignition delay period and the mixing controlled combustion phase has been recognized to be important from emission standpoint. The fuel mass fractions burned in the premixed phase is dependent on the mass preparation rate during the delay period. Based on this consideration, a gas jet multizone phenomenological model has been used for the investigation concerning the premixed combustion phase. The results concerning effect of important engine parameters viz. injection timing, injection pressure and engine speed are discussed in this paper. The effects of these parameters on engine emissions are inferred from the mass fractions burned at the ignition.

The influence of fuel characteristics on particulate emissions has been widely investigated. In this paper, the effect of different fuel properties on particulate emissions has been reviewed. The effect of fuel sulphur has been reported to have linear-relationship with the sulphate content of particulates. Combustion system, engine loading etc. were found to have weak contribution to the sulphate content variation. The results and analysis of various studies are also discussed for identifying the effect of Aromatic content, volatility, cetane number, oxygenates etc.

This paper describes the engine mapping work carried out on a 2.1 litre carburetted petrol engine.The purpose of this work was to improve upon the emission levels of the engine to meet 1996 emission norms with sufficient margin and to achieve best fuel economy possible. This paper deals with the strategy for the selection of speed load points required for mapping depending on engine operating zones, engine base data collection, methodology followed in engine mapping, variation of engine performance and emissions with respect to air/fuel ratio and spark timing etc. Further the mass emission predictions for different strategies like leaning the air/fuel mixture, retarding the ignition timing etc. are also discussed. Recalibration of the carburettor based on the above findings, its effect on vehicle performance are dealt with.

The results of the investigation of a high pressure fuel injection system (HPFIS) with small accumulator (2500 mm3) and hydraulic intensifier (1:14), are presented. This was a critical evaluation of a new HPFIS in view of the present characteristics of up-to-date conventional fuel injection systems for vehicular diesel engines. The results show the main injection characteristics and their dependence on operating regimes of a multicylinder diesel engine under stationary and transient conditions.

In India, evaporative emission norms came into effect from 1st April 1996. The ARAI commissioned a Variable Temperature/Variable Volume SHED for conducting evaporative emission tests on all Passenger Cars. The present Indian evaporative emission test procedure is in line with the 91/441/EEC test procedure with the exception of Driving Cycle. As Indian Automotive Industry needs technical inputs for designing evaporative emission control systems, it was decided to collect an exhaustive data base on evaporative emissions. This paper briefly describes evaporative emission test methods adopted in different countries and different requirement of the test equipments and specifications. This paper also describes the commissioned VT/VV SHED System capabilities and its specifications.

Road vehicles powered with internal combustion engines employing natural gas have attracted in recent years considerable interest. Apart from the widespread availability of natural gas, this interest is due to the potential to achieve extremely low emission levels in road vehicles. For some countries having natural gas sources, a promotion of natural gas may be an important part of the national energy strategy aiming at: reducing dependence on imported oil supplies reducing flare-off and wastage overcoming environmental pollution problems. This paper reviews basic aspects of gas engines and their mixture formation and combustion processes. Then the layout and characteristics of Iveco gas engines for heavy duty vehicles which are derived from present production diesel engines are described and their characteristics given.

A novel catalytic converter technology for 2 stroke engine application has been successfully developed and tested on select two wheeler vehicles. The catalytic converter uses spherical beads, as catalyst carrier, that is characterised by its very low thermal expansion coefficient and excellent thermal shock resistance. This catalyst carrier is very different from the old fixed bed pelleted catalyst carrier used in the four wheelers in late 1970's and early 1980's, in terms of its: chemical and mineralogical composition microstructure and other physical properties When suitably catalysed and canned, it offers unique advantages over conventional honeycomb catalyst on account of its high conversion efficiency, good durability and easy catalyst replacement/refill capability. The reactor which houses the catalyst bead is so designed that it offers least pressure drop across the converter and negligible power loss at WOT conditions.

An experimental study was conducted on a carburetted 2-stroke gasoline, 3-wheeler engine for operating on Compressed Natural Gas (CNG) in bi-fuel mode and further to run on dedicated CNG. Work involved design and development of a gas-air mixer for CNG, pumpless lubrication system for engine, cylinder heads for higher compression ratio, etc. Moreover, the studies for optimising the spark timing for improving CNG engine performance and effect of higher compression ratio on CNG emission, BSFC, etc. was conducted. Performance tests regarding power, BSFC, emission, etc. were conducted on baseline gasoline, bi-fuel CNG and dedicated CNG mode. Engine test bed results show that, on bi-fuel mode power loss is around 14 to 19%, which can be reduced to 5 to 10% in dedicated mode.

Metallic substrates for catalysts constitute a supporting technology to meet the various emission legislations world wide for passenger cars as well as for 2- and 3-wheelers. Hot tubes offer additional advantages, especially for 2- and 3-wheelers in combination with metallic substrates or as independent systems. Low thermal capacity data indicates an early light off. High thermal conductivity assists the catalyst under engine misfiring conditions. The wall thickness of the foil material used is responsible for low back pressure and high engine performance. The greater geometrical surface area of metallic substrates and hot tubes in combination with structured surfaces offers the automotive industry an opportunity to reduce catalyst volume. Simple, economical canning methods are a field of special interest in the automotive industry. These advantages combined allow metallic substrates a significant market share in automotive applications.

Scooters and motorcycles are favoured as economical forms of transportation throughout much of Asia. This is particularly true of vehicles with 2-stroke powerplants, thanks to the high specific output produced by this simpler, less costly engine. However, a serious disadvantage of these vehicles is that they emit considerably higher volumes of gaseous pollutants per driven kilometer than do other automobiles. Reductions of greater than 50% in these gaseous emissions can be effected through the use of catalysts to treat the exhaust from these engines. In this paper, important aspects of the operating conditions and durability requirements which must be factored into the design of durable, active catalyst formulations for these vehicles will be described.

The feasibility of using ceramic catalytic converters to reduce HC and CO emissions from 2-stroke motorcycles and scooters was investigated by performing mass emission tests on the Indian Driving Cycle. It was found that it is possible to reduce emissions significantly by installing ceramic catalytic converters at a proper location in the exhaust pipe. A power loss requirement of <5% was also met with ceramic converters. Laboratory tests on mat durability indicated that the ceramic catalytic converter package can offer excellent mechanical durability under Indian driving conditions.

Compared with gasoline powered engines, the diesel engine naturally emits dramatically lower levels of gaseous hydrocarbons, carbon monoxide, and oxides of nitrogen. The primary form of health affecting airborne pollution from diesel engines is in the form of particulate emissions. While the full potential health impact of diesel particulates remains to be understood, the combination of poor urban visibility due to “noxious smoke” emissions, inhalation related irritations, and the odor associated with diesel emissions provides ample potential for quality of life improvement through abatement of these emissions. Modern catalytic aftertreatment of diesel exhaust can have substantial impact on the particulate portion of the emission spectrum, primarily through the oxidation of the heavy hydrocarbons comprising the “soluble organic fraction” (SOF) of the particulate distribution.

A theoretical heat transfer model was applied in the design and performance prediction of an aircraft nozzle cowl anti-ice system. Laboratory heat transfer tests were conducted to determine nozzle performance in a curved D-duct specimen. The local convective film coefficient variation on the interior nose cowl surface was empirically fitted relative to the secondary flow parameters in the D-duct. The measured D-duct flow variables were in excellent agreement with the theoretical jet pump model calculations, allowing the model to predict the internal heat transfer coefficient anywhere inside the nose cowl and calculate steady state skin temperature profiles during anti-icing. By minimizing the predicted thickness of runback ice aft of the heated cowl surface, an optimum nozzle design was determined analytically. The predicted anti-ice performance of the nose cowl ice protection design was later verified by flight test measurements of nose cowl skin temperatures.

A methodology and software to automatically define airplane configurations is presented. The general airplane configuration has wing, fuselage, vertical tail, horizontal tail, canard, pylon, and engine nacelle components. The wing, tail, canard, and pylon components are manifested by solving a fourth order partial differential equation subject to Dirichlet and Neumann boundary conditions. The design variables are incorporated into the boundary conditions, and the solution is expressed as a Fourier series. The fuselage and nacelles are described with analytic equations. The methodology is called Rapid Airplane Parametric Input Design (RAPID), and both batch and interactive software based on the technique are described. Examples of high-speed civil transport configurations and subsonic transport configurations are presented.

A family of Very Large Transport (VLT) concepts were studied as an implementation of the affordability aspects of the Robust Design Simulation (RDS) methodology which is based on the Integrated Product and Process Development (IPPD) initiative that is sweeping through industry. The VLT is envisioned to be a high capacity (600 to 1000 passengers), long range (∼7500 nm), subsonic transport. Various configurations with different levels of technology were compared, based on affordability issues, to a Boeing 747-400 which is a current high capacity, long range transport. The varying technology levels prompted a need for an integration of a sizing/synthesis (FLOPS) code with an economics package (ALCCA). The integration enables a direct evaluation of the added technology on a configuration economic viability.

A comparative analysis has been performed on the Boeing 727-100 using three conceptual design codes. These programs were: The Aircraft Synthesis Program, ACSYNT, Advanced Aircraft Analysis, AAA, and RDS-Student. The objective of this study was to investigate differences in the conceptual design methodologies of these three programs. All three codes showed reasonable prediction of drag in the subsonic flow regime. However all three programs had difficulty predicting transonic drag rise characteristics. The principal cause was the inability to accurately predict the critical drag rise Mach number. Difficulties in estimating the shape of the drag rise curve, relative to the critical Mach number, also contributed to the errors in drag prediction. AAA and RDS-Student gave reasonable predictions of maximum lift coefficient. ACSYNT could not model the triple-slotted flap system on the 727-100. The three codes showed a consistent trend towards under-prediction of empty weight.

The design process is an interactive feedback process where the performance of the design is compared with the performance specification. In aircraft design it is very important that the system is optimised with respect to different aspects such as performance and weight. Traditionally, and by necessity, the design procedure has began with some kind of performance specification followed by a conceptual design, and after that the system has been optimised (usually implicitly) with respect to the performance specification. Typically, aircraft design optimisation is characterised by a multitude of objectives that can be difficult to compare to each other, such as low fuel consumption, high speed and passenger comfort. Usually this is where the engineering judgement of the designer comes in. In traditional design it is often difficult to establish what was the result of design decisions and what was the result of pure optimisation.

The relationships between rotorcraft physical dimensions and their performance characteristics to vertiport/heliport design criteria have recently been critically evaluated. These evaluations have been conducted by the Federal Aviation Administration (FAA), the National Aeronautics and Space Administration (NASA), and by representatives from the vertical flight industry and academia. These efforts were prompted by the anticipated ability of advanced rotorcraft to provide airport and ground traffic congestion relief through commercial air transportation services on some short-haul routes after the year 2000. This paper discusses the results of these investigations and their impact on vertiport design issues, criteria, and future research and development (R&D) requirements.

This paper explores the urban design problem that the Vertiport poses for integration into the urban fabric and transportation systems. It discusses the complex challenges of site selection, intermodalism, and community acceptance. The paper presents a generic design prototype of a Vertiport for urban harbors as a solution for the land use, site selection, and community acceptance issues.

A personal computer based preliminary design system for aircraft demonstrates a practical method to design and analyze any aircraft configuration. The program provides a powerful framework to support the non-unique process of aircraft preliminary design. The system will allow design engineers to rapidly evolve an aircraft configuration from weight sizing through detailed performance calculations, while working within regulatory constraints. The program is designed to reduce the preliminary design phase cost and to bring advanced design methods to small businesses and universities.