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The study of aerodynamic forces in hypersonic environments is important to ensure the safety and proper functioning of aerospace vehicles. These forces vary with the angle of attack (AOA) and there exists an optimum angle of attack where the ratio of the lift to drag force is maximum. In this paper, computational analysis has been performed on a blunt cone model to study the aerodynamic characteristics when hypersonic flow is allowed to pass through the model. The flow has a Mach number of 8.44 and the angle of attack is varied from 0º to 20º. The commercial CFD solver ANSYS FLUENT is used for the computational analysis and the mesh is generated using the ICEM CFD module of ANSYS. Air is selected as the working fluid. The simulation is carried out for a time duration of 1.2 ms where it reaches a steady state and the lift and drag forces and coefficients are estimated. The pressure, temperature, and velocity contours at different angles of attack are also observed.

Modern combat aircraft demands efficient maintenance strategies to ensure operational readiness while minimizing downtime and costs. Innovative approaches using Digital Twining models are being explored to capture inter system behaviours and assessing health of systems which will help maintenance aspects. This approach employs advanced deep learning protocols to analyze the intricate interactions among various systems using the data collected from various systems. The research involves extensive data collection from sensors within combat aircraft, followed by data preprocessing and feature selection, using domain knowledge and correlation analysis. Neural networks are designed for individual systems, and hyper parameter tuning is performed to optimize their performance. By combining the outputs of these during the model integration phase, an overall health assessment of the aircraft will be generated.

The current research focuses on enhancing the performance of Si solar cells by using Er2O3 (Erbium Oxide) in cubic crystalline nature serves as an anti-reflection coating material. An anti-reflective coating aims to improve the Efficient Power Conversion (EPC) of polycrystalline silicon wafers solar cells (PSSC) utilised in solar roof panels of the automotive sector. It also exhibits superior light transmittance and least light reflectance, which eventually leads to the increase EPC. Erbium oxide helps to convert low energy photons into high energy photons. The incident photons, which lies on the solar cell, gradually losses its energy to travel in a denser medium and dissipate in the form of heat energy. In order to overcome the rate of reflection, current research aims in synthesis of erbium oxide nanosheets using electrospinning deposition technique for varying deposition timings such as 1, 1.5 and 2 hours.

Graphite plays a crucial role in friction materials, since it has good thermal conductivity, lubricity and act as a friction modifier. The right type, amount, shape, and size of the particles control the performance of the brake-pads. The theme of the study was investigating the influence of size of graphite particles (having all other specifications identical) on performance properties of brake-pads containing graphite particles in the average size of 60 μm, 120 μm, 200 μm and 400 μm. Physical, mechanical and chemical characterization of the developed brake-pads was done. The tribological performance was studied using a full- scale inertia brake dynamometer following a Japanese automobile testing standard (JASO C406). Tribo-performance in terms of fade resistance, friction stability and wear resistance were observed best for smaller graphite particles. It was concluded that smaller size serves best for achieving best performance properties barring compressibility.

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.

In this work methanol was port injected while diesel was injected using a common rail system in a single cylinder non-road CI engine. Experiments were conducted with single (SPI) and double (DPI - pilot and main) injection of the directly injected diesel at 75% load and at a constant speed of 1500 rpm. The effects of methanol to diesel energy share (MDES) and injection scheduling on combustion stability, efficiency and emissions were evaluated. Initially, in the SPI mode, the methanol to diesel Energy Share (MDES) was varied, while the injection timing of diesel was always fixed for best brake thermal efficiency (BTE). Increase in the MDES resulted in a reduction in NOx and smoke emissions because of the high latent heat of vaporization of methanol and the oxygen available. Enhanced premixed combustion led to a raise in brake thermal efficiency (BTE). Coefficient of variation of IMEP, peak pressure and BTE were deteriorated which limited the usable MDES to 43%.

Among the various Low Temperature Combustion (LTC) strategies, Homogeneous Charge Compression Ignition (HCCI) is most promising to achieve near zero oxides of nitrogen (NOx) and particulate matter emissions owing to higher degree of homogeneity and elimination of diffusion phase combustion. However, one of its major limitations include a very narrow operating load range owing to misfire at low loads and knocking at high loads. Implementing HCCI in small light duty air cooled diesel engines pose challenges to eliminate misfire and knocking problems owing to lower power output and air cooled operation, respectively. In the present work, experimental investigations are done in HCCI mode in one such light duty production diesel engine most widely used in agricultural water pumping applications. An external mixture preparation based diesel HCCI is implemented in the test engine by utilizing a high-pressure port fuel injection system, a fuel vaporizer and an air preheater.

Experiments were conducted on a turbocharged three cylinder automotive common rail diesel engine with port injection of butanol. This dual fuel engine was run with neat butanol and blends of water and butanol (up to 20% water by mass). Experiments were performed at a constant speed of 1800 rpm and a brake mean effective pressure of 11.8 bar (full load) at varying butanol to diesel energy share values while diesel was either injected as a single pulse or as twin pulses (Main plus Post). Open engine controllers were used for varying the injection parameters of diesel and butanol. Water butanol blends improved the brake thermal efficiency by a small extent because of better combustion phasing as compared to butanol without water. When the butanol to diesel energy share was high, auto-ignition of butanol occurred before the injection of diesel. This lowered the ignition delay of diesel and hence elevated the smoke level.

In this study, 3D air-flow-field evolution in a single cylinder optical research engine was determined using tomographic particle imaging velocimetry (TPIV) at different engine speeds. Two directional projections of captured flow-field were pre-processed to reconstruct the 3D flow-field by using the MART (multiplicative algebraic reconstruction technique) algorithm. Ensemble average flow pattern was used to investigate the air-flow behavior inside the combustion chamber during the intake and compression strokes of an engine cycle. In-cylinder air-flow characteristics were significantly affected by the engine speed. Experimental results showed that high velocities generated during the first half of the intake stroke dissipated in later stages of the intake stroke. In-cylinder flow visualization indicated that large part of flow energy dissipated during the intake stroke and energy dissipation was the maximum near the end of the intake stroke.

Diesel particulates are mainly composed of elemental carbon (EC) and organic carbon (OC) with traces of metals, sulfates and ash content. Organic fraction of the particulate are considered responsible for its carcinogenic effects. Diesel oxidation catalyst (DOC) is an important after-treatment device for reduction of organic fraction of particulates. In this study, two non-noble metal based DOCs (with different configurations) were prepared and evaluated for their performance. Lanthanum based perovskite (LaMnO3) catalyst was used for the preparation of DOCs. One of the DOC was coated with support material ceria (5%, w/w), while the other was coated without any support material. Prepared DOCs were retrofitted in a four cylinder water cooled diesel engine. Various emission parameters such as particulate mass, particle number-size distribution, regulated and unregulated emissions, EC/OC etc., were measured and compared with the raw exhaust gas emissions from the prepared DOCs.

Fuel-air mixing is the main parameter, which affects formation of NOx and PM during CI combustion. Hence better understanding of air-flow characteristics inside the combustion chamber of a diesel engine became very important. In this study, in-cylinder air-flow characteristics of four-valve diesel engine were investigated using time-resolved high-speed tomographic Particle Imaging Velocimetry (PIV). For visualization of air-flow pattern, fine graphite particles were used for flow seeding. To investigate the effect of different operating parameters, experiments were performed at different engine speeds (1200 rpm and 1500 rpm), intake air temperatures (room temperature and 50°C) and intake port configurations (swirl port, tangential port and combined port). Intake air temperature was controlled by a closed loop temperature controller and intake ports were deactivated by using a customized aluminum gasket.

The replacement of fossil diesel with neat biodiesel in a compression ignition engine has advantage in lowering unburned hydrocarbon, carbon monoxide and smoke emissions. However, the injection advance experienced with biodiesel fuel with respect to diesel injection setting increases oxides of nitrogen emission. In this study, the biodiesel-NO control is attempted using charge and fuel modification strategies with retarded injection timing. The experiments are performed at maximum torque speed and higher loads viz. from 60% up to full load conditions maintaining same power between diesel and biodiesel while retarding the timing of injection by 3 deg. crank angle. The charge and fuel modifications are done by recycling 5% by volume of exhaust gas to the fresh charge and 10% by volume of methanol to Karanja biodiesel.

Better understanding of flow phenomena inside the combustion chamber of a diesel engine and accurate measurement of flow parameters is necessary for engine optimization i.e. enhancing power output, fuel economy improvement and emissions control. Airflow structures developed inside the engine combustion chamber significantly influence the air-fuel mixing. In this study, in-cylinder air flow characteristics of a motored, four-valve diesel engine were investigated using time-resolved high-speed Tomographic Particle Imaging Velocimetry (PIV). Single cylinder optical engine provides full optical access of combustion chamber through a transparent cylinder and flat transparent piston top. Experiments were performed in different vertical planes at different engine speeds during the intake and compression stroke under motoring condition. For visualization of air flow pattern, graphite particles were used for flow seeding.

Road accidents and persons killed in India have been reported to the tune of 4,90,383 and 1,38,258 respectively during 2012. On National Highways (NHs), major share of accidents (about 29%) and number of persons killed (35.3%) are observed out of total accidents. National Highways in India constitute about 2% of total road network (92,851 km) in India, but carries about 40% of traffic. 46% (42,829 km) of NHs in India comprises of two-lane and about 19% (17239 km) of NHs are single or intermediate-lane. Road accidents being multi-disciplinary in nature involves attention of multiple departments such as Highways Authority, Police, Motor Vehicles, Automobile Manufacturers, NGOs, etc. Owing to spurt in growth of motor vehicle population in India, road accidents are not reduced significantly despite improvement in NHs (widening of carriageway and riding quality).

The effect of different cold- rolling and cryo-rolling routes on the strength and ductility of Al-6061 alloy was thoroughly investigated. Rolling decreased the grain size and increased the strength according to the Hall-Petch relationship. However subjecting the samples to ageing at different temperatures and for different time period increased the strength and improved the ductility. The ductility was improved due to the rearrangement and even decrease in dislocation density due to recovery and recrystallization during ageing while the strength was maintained due to ageing. Evolution of microstructure was investigated by optical microscopy, scanning electron microscopy. Preliminary hardness measurements coupled with tensile tests indicate the improvement of both yield strength and ductility. The disparity in ultimate tensile strength, yield strength and the elongation to failure with different ageing temperatures and for different time period is determined and discussed.

Performance of a Current generation catalytic converter using Pd/Rh (10:1) as binary catalyst impeded on an ultra thin ceramic substrate and alumina wash coat is modeled for performance prediction and parametric optimization. Kinetic rates for the catalyst are reduced after conducting series of experiments on a passenger car engine. A new concept in mass transfer coefficient is introduced for improving accuracy of the model prediction. In order to take care of the precious metal resources and to become independent of precious metal price fluctuation, a new pattern of loading of precious metal is suggested for optimum performance and metal savings about 46 percent was observed. Experimental investigations were carried out to validate the established kinetic rates over a wide range operation of the engine and for the model validation. Satisfactory agreements are observed for the model prediction and experimental results.

In the present study, a 17 kW, stationary, direct- injection diesel engine has been converted to operate it as a gas engine using producer-gas and compressed natural gas (CNG) as the fuels on two different operational modes called SIPGE (Spark Ignition Producer Gas Engine) and DCNGE (Dedicated Compressed Natural Gas Engine). The engine before conversion, was run on two other modes of operation, namely, diesel mode using only diesel and producer-gas-diesel-dual-fuel mode with diesel used for pilot ignition. The base data generated on diesel mode was used for performance comparison under other modes to ascertain the fuel flexibility. A technology development and optimisation followed by performance confirmation are the three features of this study. The exercise of conversion to SIPGE is a success since comparable power and efficiency could be developed. DCNGE operation also yielded comparable power with higher efficiency, which establishes the fuel flexibility of the converted machine.

Three catalysts based on X-zeolite have been developed by exchanging its Na+ ion with Copper, Nickel and Vanadium metal ions and tested in a stationary SI engine exhaust to observe their potentialities for NOx and CO controlling. The catalyst Cu-X, in comparison to Ni-X and V-X, exhibits much better NOx and CO reduction performance at any temperature. Maximum NOx conversion efficiencies achieved with Cu-X, Ni-X and V-X are 62.2%, 59.7% and 56.1% respectively. Unlike noble metals, the doped X-zeolite catalysts, studied here, maintain their peak NOx reduction performance through a wider range of A/F ratio. Back pressure developed across the catalyst bed is found to be well within the acceptable limits.