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Flow variations from one cycle to the next significantly influence the mixture formation and combustion processes in engines. Therefore, it is important to understand the fluid motion and its cycle-to-cycle variations (CCVs) inside the engine cylinder. Researchers have generally investigated the cycle-to-cycle flow variations in moderate- to large-sized engines. In the present work, we have performed the flow measurement and analysis in a small spark-ignition engine. Experiments are conducted in an optically accessible, single-cylinder, port-fuel-injection engine with displacement volume of 110 cm3 at different throttle openings (i.e. 50% and WOT) using particle image velocimetry. Images are captured at different crank angle positions during both intake and compression strokes over a tumble measurement plane, bisecting the intake and exhaust valves and passing through the cylinder axis.

This paper presents the experimental investigation of combustion stability and nano-particle emissions from the CNG-diesel RCCI engine. A modified automotive diesel engine is used to operate in RCCI combustion mode. An open ECU is used to control the low and high reactivity fuel injection events. The engine is tested for fixed engine speed and two different engine load conditions. The tests performed for various port-injected CNG masses and diesel injection timings, including single and double diesel injection strategy. Several consecutive engine cycles are recorded using in-cylinder combustion pressure measurement system. Statistical and return map techniques are used to investigate the combustion stability in the CNG-diesel RCCI engine. Differential mobility spectrometer is used for the measurement of particle number concentration and particle-size and number distribution. It is found that advanced diesel injection timing leading to higher cyclic combustion variations.

Stringent emission regulations on one hand and increasing demand for better fuel economy along with lower noise levels on the other hand require adoption of advanced common-rail direct-injection technologies in diesel engines. In the present work, a small 0.9-l, naturally aspirated, two-cylinder, common-rail direct-injection diesel engine is used for the analysis of combustion noise at different engine operating conditions. Experiments are conducted at different loads and engine speeds, incorporating both single and multiple (i.e. pilot and main) injections along with different injection timings. In the case of multiple injections, the influence of pilot injection quantity is also evaluated on the combustion noise while maintaining the same load. In-cylinder pressure was recorded with the resolution of 0.1 crank angle degree, and it was used for the quantitative analysis of noise assessed from the resulting cylinder pressure spectra, and sound pressure level.

In a direct-injection (DI) engine, charge motion and mixture preparation are among the most important factors deciding the performance and emissions. This work was focused on studying the effect of injector positioning on fuel-air mixture preparation and fuel impingement on in-cylinder surfaces during the homogeneous mode of operation in a naturally aspirated, small bore, 0.2 l, light-duty, air-cooled, four-stroke, spark-ignition engine modified to operate under the DI mode. A commercially available, six-hole, solenoid-operated injector was used. Two injector locations were identified based on the availability of the space on the cylinder head. One location yielded the spray-guided (SG) configuration, with one of the spray plumes targeted towards the spark plug. In the second location, the spray plumes were targeted towards the piston top in a wall-guided (WG) configuration so as to minimize the impingement of fuel on the liner.

Experimental investigations relating to the performance and emission characteristics under idling conditions of a three cylinder passenger car spark ignition engine operating on a conventional carburettor and a developed single point gasoline fuel injection system are described in this paper. The idling performance at different engine speeds was studied by carrying out comprehensive engine testing on a test bed in two phases. In the first phase, experiments were conducted on an engine fitted with a conventional carburettor whilst they were extended to the engine provided with a developed electronic single point fuel injection (SPI) system, whose fuel spray was directed against the direction of air flow. The injection timing of the SPI system was varied from 82 deg. before inlet valve opening (or 98 deg. before top dead center) to 42 deg. after inlet valve opening (or 26 deg. after top dead center).

A gas turbine combustion system is an embodiment of all complexities that engineering equipment can have. The flow is three dimensional, swirling, turbulent, two phase and reacting. The design and development of combustors, until recent past, was an art than science. If one takes the route of development through experiments, it is quite time consuming and costly. Compared to the other two components viz., compressor and turbine, the combustion system is not yet completely amenable to mathematical analysis. A gas turbine combustor is both geometrically and fluid dynamically quite complex. The major challenge a combustion engineer faces is the space constraint. As the combustion chamber is sandwiched between compressor and turbine there is a limitation on the available space. The critical design aspect is in facing the aerodynamic challenges with minimum pressure drop. Accurate mathematical analysis of such a system is next to impossible.

Increasing the efficiency of engine auxiliary systems have become a challenge. Oil pump, identified for this study, is one such engine system which is used for lubrication of engine parts. To achieve higher efficiencies, there is a need for math-based analysis and design. This can be achieved by means of Computational Fluid Dynamics (CFD). The main aim of this paper is to simulate the flow through Gerotor Oil pump using Computational Fluid Dynamics. A 3D model of the entire flow domain is created and meshed in preprocessor GAMBIT. The mesh for various pressure outlet conditions is exported to FLUENT solver for analysis. The predicted results are validated with the experimental results. The comparison shows that the CFD predictions are in good agreement with experimental results. In particular, such a simulation offers a scope for visualizing the flow through the Gerotor oil pump.

This paper deals with the experimental investigation carried out to study the effect of expansion ratio (ER) on the brake thermal efficiency of a spark ignition ( S.I. ) engine. Intake valve closure timing (IVCT) and clearance volume have been suitably altered to achieve different ERs and compression ratios (CRs). For the modified engines the ratio of ER to CR ranges from 1:1 to 2.27:1, for CRs of 6,7, and 8:1. The results have been compared with the standard version of the engine with compression ratio of 7 and 8:1. Brake thermal efficiency improvement up to 35% has been achieved with a combination of variable IVCT (VIVCT) and variable CR (VCR) at part - load operation. Results show that in this system CR can be lowered without penalizing the thermal efficiency of the engine. Results indicate that the thermal efficiency of an Extended Expansion Engine with a CR of 6:1 and ER/CR equal to 1.5 is equal to the thermal efficiency of a standard engine with a CR of 8:1.

Advanced low temperature combustion (LTC) modes are most promising to reduce green house gas emissions owing to fuel economy benefits apart from simultaneously reducing oxides of nitrogen (NOx) and particulate matter (PM) emissions from diesel engines. Various LTC strategies have been proposed so far and each of these LTC strategies have their own advantages and limitations interms of precise ignition control, achievable load range and higher unburned emissions. In the present work, a small single cylinder diesel engine is initially operated under conventional combustion mode at rated speed, varying load conditions to establish the base line reference data. Then, the engine is modified to operate under different LTC strategies including Homogenous Charge Compression Ignition (HCCI), Premixed Charge Compression Ignition (PCCI) and Reactivity Controlled Compression Ignition (RCCI).

Reactivity controlled compression ignition (RCCI) is one of the most promising low temperature combustion (LTC) strategies to achieve higher thermal efficiencies along with ultra low oxides of nitrogen (NOx) and particulate matter emissions. Small single cylinder diesel engines of air-cooled type are finding increasing applications in the agriculture pump-set and small utility power generation owing to their lower cost and fuel economy advantages. In the present work, a small single cylinder diesel engine is initially operated under conventional combustion mode at rated speed, varying load conditions to establish the base line reference data. Then, the engine is modified to operate under RCCI combustion mode with a newly designed cylinder head to accommodate a high pressure, fully flexible electronically controlled direct diesel fuel injection system, a low pressure gasoline port fuel injection system and an intake air pre heater.

Minimum weight and high-efficiency gearboxes with the maximum service life are the prime necessity of today’s high-performance power transmission systems such as automotive and aerospace. Therefore, the problem to optimize the gearboxes is subjected to a considerable amount of interest. To accomplish these objectives, in this paper, two generalized objective functions for two stage spur-gearbox are formulated; first objective function aims to minimize the volume of gearbox material, while the second aims to maximize the power transmitted by the gearbox. For the optimization purpose, regular mechanical and critical tribological constraints (scuffing and wear) are considered. These objective functions are optimized to obtain a Pareto front for the two-stage gearbox using a specially formulated discrete version of non-dominated sorting genetic algorithm (NSGA-II) code written MATLAB. Two cases are considered, in the first with the regular mechanical constraints.

Of late direct injection engines are replacing carburetted and port injected engines due to their high thermal efficiency and fuel economy. One of the reasons for the increased fuel economy is the ultra lean mixture with which the engine operates under low loads. Under the low load conditions, the air fuel ratio of the mixture near the spark plug is close to stoichiometric values while the overall mixture is lean, which is called stratified mixture. In order to achieve this, proper air motion during the late stages of compression is a must. Quality of the mixture depends on the time of injection as well as the type of fuel injector and mixture preparation strategy used. Engines employing air guided mixture preparation are considered as the second generation engines. For understanding the efficient mixture preparation method, three types of flow structures like base (low tumble), high tumble and inclined swirl are created inside the engine cylinder using shrouds on the intake valves.

Copper ion-exchanged X-zeolite with urea infusion was tested for nitrogen oxide (NOx)conversion efficiency in this study. Temperature datapoints were obtained to arrive at peak activation temperatures. Variation of the air/fuel ratio showed the widening of the λ-window(the range of air-fuel ratios over which the NOx conversion efficiency is considerable); a maximum of 62% NOx conversion efficiency was obtained in the lean-burn range. Effects of space velocity variations were also observed. In order to minimise the deactivation of zeolite caused by water, ammonium carbonate and ammonium sulphate were deposited on the copper ion-exchanged X-zeolite and the corresponding NOx conversion efficiencies measured. Ammonia slip (leakage of unreacted ammonia), a prospective pollution hazard, was observed to be more in case of urea infusion than ammonium salt deposition at higher temperatures.

Evaluation of combustion parameters such as ignition delay and combustion duration are very important in the design and development of reciprocating diesel engines. So far, there is no established and straight, forward method for the estimation of these parameters. In this paper first the available methods have been reviewed. Limitations of the direct method have been discussed. Effect of some operating variables like compression ratio, speed, load and injection advance on the combustion parameters have been studied. An easy and reliable approach has been suggested for the determination of start and end of combustion for a direct injection diesel engine, minimizing the personal judgment. Procedure for calculating the ignition delay and combustion duration based on the experimental study has been highlighted for the proposed method.

As alternate fuels, ethyl and methyl alcohols stand out because of the feasibility of producing them in bulk from plentifully available raw materials. In the present work, ethanol is used as the only fuel, in the standard and Low Heat Rejection(LHR) diesel engines by adopting three different methods. In the first method, ethanol as the sole fuel was used in the LHR engine with normal metal glowplug and in the second method spark plug assistance was used to initiate combustion. In the third method, ethanol was used as the sole fuel in a LHR engine and a ceramic glow plug was used to initiate combustion. The engine was tested for performance and emissions for the above three methods of 100% ethanol operation in both the standard and LHR diesel engine and the results are compared. The spark plug assisted ethanol operation in the LHR engine gave the highest brake thermal efficiency and the lowest emissions.

Use of methanol and ethanol in conventional diesel engines is associated with problems on account of the high self ignition temperature of these fuels. The Hot Surface Ignition (HSI) method wherein a part of the injected fuel is made to touch an electrically heated hot surface for ignition, is an effective way of utilizing these fuels in conventional diesel engines. In the present work two types of HSI engines, one using a large ceramic base and the other using a conventional glowplug were developed. These engines were tested with methanol, M.spirit (about 90 % methanol and 10 % ethanol) and diesel. The results of performance, fuel economy emissions and combustion parameters including heat release rates for these fuels with both the types of HSI engines are presented. Diesel engines are commonly used as primemovers in the mass transportation and agricultural sectors because of their high brake thermal efficiency and reliability.

Hydrocarbon emissions due to short-circuiting of the fresh charge during scavenging process is a major source of pollution from the two-stroke spark ignition engines. This work presents a prediction scheme for analysis of hydrocarbon emission based on the material balance considerations. A generalized form of globular combustion equation has been used for general applicability of the scheme to any fuel or fuel blends. The influence of mixture quality, scavenging characteristics, residual contents and the delivery ratio are predicted. A good qualitative prediction has been established at all delivery ratios. The predictions are found quantitatively satisfactory in the higher delivery ratio range where the short-circuiting phase of the scavenging process is dominant.

The performance of a conventional, carbureted, two-stroke spark-ignition (SI) engine can be improved by providing moderate thermal insulation in the combustion chamber. This will help to improve the vaporization characteristics in particular at part load and medium loads with gasoline fuel and high-latent-heat fuels such as methanol. In the present investigation, the combustion chamber surface was coated with a 0.5-mm thickness of partially stabilized zirconia, and experiments were carried out in a single-cylinder, two-stroke SI engine with gasoline and methanol as fuels. Test results indicate that with gasoline as a fuel, the thin ceramic-coated combustion chamber improves the part load to medium load operation considerably, but it affects the performance at higher speeds and at higher loads to the extent of knock and loss of brake power by about 18%. However, with methanol as a fuel, the performance is better under most of the operating range and free from knock.

The use of alcohol-gasoline blends enables the favorable features of alcohols to be utilized in spark ignition (SI) engines while avoiding the shortcomings of their application as straight fuels. Eucalyptus and orange oils possess high octane values and are also good potential alternative fuels for SI engines. The high octane value of these fuels can enhance the octane value of the fuel when it is blended with low-octane gasoline. In the present work, 20 percent by volume of orange oil, eucalyptus oil, methanol and ethanol were blended separately with gasoline, and the performance, combustion and exhaust emission characteristics were evaluated at two different compression ratios. The phase separation problems arising from the alcohol-gasoline blends were minimized by adding eucalyptus oil as a co-solvent. Test results indicate that the compression ratio can be raised from 7.4 to 9 without any detrimental effect, due to the higher octane rating of the fuel blends.

This work demonstrates how the performance of a standard spark-assisted alcohol engine can be improved by using the Low Heat Rejection (LHR ) concept. The improved combustion is attained by better using the greater heat energy in the combustion chamber of a LHR engine - in this case for the faster vaporisation and better mixing of the alcohol fuels. For this program the LHR engine used has a single cylinder diesel and alcohols sued as sole fuels were ethanol and methanol. For spark assistance an extended electrode spark plug was used and location and projection were optimised for best results. These configurations were evaluated for performance and emissions with and without LHR implementation. The results show that the engine with LHR, ethanol fuel and spark assistance has the highest brake thermal efficiency with the lowest emissions.