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Gasket sealing performance of a manifold is traditionally characterized either by pressure distribution on flange face or line loads on gasket beads. These readings are sometimes susceptible to error due to complex contact algorithms or lack of reliable gasket data. In addition, they are difficult to correlate, particularly in the case of log-type manifolds. Here, a different approach for assessing gasket sealing performance of exhaust manifolds is presented based on overall manifold distortion under thermo-mechanical loading. Current technical paper describes the methodology used and presents a validation work.

Abstract TOC

Abstract Traditionally, in combustion engine applications, metallic materials have been widely employed due to their properties: castability and machinability with accurate dimensional tolerances, good mechanical strength even at high temperatures, wear resistance, and affordable price. However, the high thermal conductivity of metallic materials is responsible for consistent losses of thermal energy and has a strong influence on pollutant emission. A possible approach for reducing the thermal exchange requires the use of thermal barrier coating (TBC) made by materials with low thermal conductivity and good thermo-mechanical strength. In this work, the effects of a ceramic coating for thermal insulation of the piston crown of a car diesel engine are investigated through a numerical methodology based on finite element analysis. The study is developed by considering firstly a thermal analysis and then a thermo-structural analysis of the component.

Abstract In this study low temperature plasma technology was applied to expand auto-ignition operation region and control auto-ignition phasing of the homogeneous charge compression ignition (HCCI) combustion. The low temperature plasma igniter of a barrier discharge model (barrier discharge igniter (BDI)) with high-frequency voltage (15 kHz) was provided at the top center of the combustion chamber, and the auto-ignition characteristics of the HCCI combustion by the low temperature plasma assistance was investigated by using a single-cylinder gasoline engine. HCCI combustion with compression ratio of 15:1 was achieved by increasing the intake air temperature. The lean air-fuel (A/F) ratio limit and visualized auto-ignition combustion process on baseline HCCI without discharge assistance, spark-assisted HCCI, and BDI-assisted HCCI were compared.

Abstract The Formula SAE (FSAE) is an international engineering competition where a Formula style race car is designed and built by students from worldwide universities. According to FSAE regulation, an air restrictor with circular cross section of 20 mm for gasoline-fuelled and 19 mm for E-85-fuelled vehicles is to be incorporated between the throttle valve and engine inlet. The sole purpose of this regulation is to limit the airflow to the engine used. The only sequence allowed is throttle valve, restrictor and engine inlet. A new approach of combining ram theory and acoustic theory methods are investigated to increase the performance of the engine by designing an optimized intake runner for a particular engine speed range and an optimized plenum volume in this range. Engine performance characteristics such as brake power, brake torque and volumetric efficiency are taken into considerations.

Abstract Higher water evaporation and proper water vapor distribution in the cylinder are very vital for improving emission and performance characteristics of water-injected engines. The concentration of water vapor should be higher and uniform near the walls of the combustion chamber and nil at the spark plug location. In direct water-injected engines, water evaporation, vapor distribution, and spray impingement are highly dependent on injector parameters, viz., water injector orientation (WIO), location, and spray angle. Therefore, in this article, a computational fluid dynamics (CFD) investigation is conducted to study the effects of water injector spray angle (WISA), and WIO on the water evaporation, emission, and performance characteristics of a four-stroke, wall-guided gasoline direct injection (GDI) engine. The WISA is varied from 10° to 35°, whereas the WIO is varied from 15° to 35° in steps of 5°.

Abstract One of the key factors for accurate mass burn fraction and energy conversion point calculations is the accuracy of the compression ratio. The method presented in this article suggests a workflow that can be applied to determine or correct the compression ratio estimated geometrically or measured using liquid displacement. It is derived using the observation that, in a motored engine, the heat losses are symmetrical about a certain crank angle, which allows for the derivation of an expression for the clearance volume [1]. In this article, a workflow is implemented in real time, in a current production engine indicating system. The goal is to improve measurement data quality and stability for the energy conversion points calculated during measurement procedures. Experimental and simulation data is presented to highlight the benefits and improvement that can be achieved, especially at the start of combustion.

Abstract An in-cylinder combustion analysis and a computational fluid dynamics (CFD) coolant flow analysis were performed using AVL FIRE software, which provided the heat transfer boundary conditions (HTBCs) to the temperature field calculation of the cylinder head. Based on the measured material performance parameters such as stress-strain curve under different temperatures and E-N curve, creep, and oxidation data material performance, the cylinder head-gasket-cylinder block finite element analysis (FEA) was performed. According to the temperature field calculation results, the maximum temperature of the cylinder head is 200°C that is within the limit of ALU material. The temperature of the water is more than 21.1°C below the critical burnout point temperature. The high-cycle fatigue (HCF) and thermal-mechanical fatigue (TMF) analysis of the cylinder head were performed by FEMFAT software.

Abstract In recent years, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigations. With this solution, in fact, it is possible to simultaneously reduce NOx raw emissions and fuel consumption due to decreased heat losses, higher thermodynamic efficiency, and enhanced knock resistance. However, the real applicability of this technique is strongly limited by the increase in cyclic variation and the occurrence of misfire, which are typical for the combustion of homogeneous lean air/fuel mixtures. The employment of a Pre-Chamber (PC), in which the combustion begins before proceeding in the main combustion chamber, has already shown the capability of significantly extending the lean-burn limit. In this work, the potential of an ultralean PC SI engine for a decisive improvement of the thermal efficiency is presented by means of numerical and experimental analyses.

Abstract Direct dual fuel stratification (DDFS) strategy benefits the advantages of the RCCI and PPC strategies simultaneously. DDFS has improved control over the heat release rate, by injecting a considerable amount of fuel near TDC, compared to RCCI. In addition, the third injection (near TDC) is diffusion-limited. Consequently, piston bowl geometry directly affects the formation of emissions. The modified piston geometry was developed and optimized for RCCI by previous scholars. Since all DDFS experimental tests were performed with the modified piston profile, the other piston profiles need to be investigated for this strategy. In this article, first, a comparative study between the three conventional piston profiles, including the modified, stock, and scaled pistons, was performed. Afterward, the gasoline injector position was shifted to the head cylinder center for the stock piston. NOX emissions were improved; however, soot was increased slightly.

Abstract Interactions between fuel sprays and stepped-lip diesel piston bowls can produce turbulent flow structures that improve efficiency and emissions, but the underlying mechanisms are not well understood. Recent experimental and simulation efforts provide evidence that increased efficiency and reduced smoke emissions coincide with the formation of long-lived, energetic vortices during the mixing-controlled portion of the combustion event. These vortices are believed to promote fuel-air mixing, increase heat-release rates, and improve air utilization, but they become weaker as main injection timing is advanced nearer to the top dead center (TDC). Further efficiency and emissions benefits may be realized if vortex formation can be strengthened for near-TDC injections. This work presents a simulation-based analysis of turbulent flow evolution within a stepped-lip combustion chamber.

Abstract Cycle-by-cycle combustion prediction in real time during engine operation can serve as a vital input for operating at optimal performance conditions and for emission control. In this work, a real-time capable physics-based combustion model has been proposed for the prediction of the heat release rate in a direct injection diesel engine. The model extends the approaches proposed earlier in the literature by considering spray dynamics such as spray penetration and Sauter mean diameter in order to calculate the mass of evaporated fuel from the spray. Wall impingement of the liquid spray is predicted by considering the liquid length based on the prevailing in-cylinder conditions. These effects are considered even after the hydraulic end of injection till the last droplet of fuel impinges on the combustion chamber wall. The fuel evaporated from the wall film and its contribution to the kinetic energy of the charge are also considered.

Abstract Diesel engines include systems for cooling, lubrication, and fuel injection and contain a variety of components. A malfunction in any of the engine systems or the presence of any faulty element influences engine performance and deteriorates its components. This research is concerned with the untimely appearance of vital cracks in the liners of a turbocharged heavy-duty Diesel engine. To find the root causes for premature failure, rigorous examinations through visual observations, material characterization, and metallographic investigations are performed. These include Scanning Electron Microscope (SEM) and Energy-Dispersive Spectroscopy (EDS), fracture mechanics analysis, and performance examination, which are also followed by Finite Element Moldings. To find the proper remedy to resolve the problem, drawing a precise and reliable picture of the engine’s operating conditions is required.

The interaction of fuel sprays with in-cylinder air flow is crucially important for the mixture preparation and subsequent combustion processes in gasoline direct injection (GDI) engines. In the present work, the experimentally validated computational fluid dynamics (CFD) simulations are performed to study the dynamics and physical insight of hollow-cone sprays interacting with a uniform crossflow. The basis of the model is the standard Reynolds-averaged Navier-Stokes (RANS) approach coupled to the Lagrangian treatment for statistical groups (parcels) representing the physical droplet population. The most physically suitable hybrid breakup models depicting the liquid sheet atomization and droplet breakup processes based on the linear instability analysis and Taylor analogy theory (LISA-TAB) are used. Detailed comparisons are made between the experiments and computations in terms of spray structure, local droplet diameter and velocity distributions.

The single piece aluminium alloy piston remains the dominant and preferred design offering for highly loaded diesel engines. Piston manufacturers have progressively developed aluminium alloys, machining capability, and design geometries to cope with increasing thermal and mechanical loading. In conjunction with these developments, the methodology used to analyse the pistons has also improved as software and digital computers have advanced. This advancement has permitted larger more detailed models and more sophisticated simulation of the material behaviour, in response to the loading and contact conditions applied to pistons. Transient finite element analysis was first applied to diesel pistons in the late 1970's using a linear elastic approach, coupled with a life assessment based on limited low cycle fatigue data. This methodology gave valuable insights into the mechanism of piston failures, particularly at the combustion bowl rim of diesel pistons.

The development of high efficiency powertrains is a key objective for car manufacturers. One approach for improving the efficiency of gasoline engines is based on homogeneous charge compression ignition, HCCI, which provides higher efficiency than conventional strategies. However, HCCI is only currently viable at relatively low loads, primarily because at high loads it involves rapid combustion that generates pressure oscillations in the cylinder (ringing), and partly because it gives rise to relatively high NOX emissions. This paper describes studies aimed at increasing the viability of HCCI combustion at higher loads by using fully flexible valve trains, direct injection with charge stratification (SCCI), and intake air boosting. These approaches were complemented by using EGR to control NOX emissions by stoichiometric operation, which enables the use of a three-way catalyst.

The objective of the research is to develop a lightweight yet stiff, 2 piston fixed brake caliper which can be used in formula student race car. To make a race car, its components need to be lighter. To stop a car with minimum stopping distance, it needs to have a sophisticated braking system with well-designed components. The designing of the caliper is carried out on the Altair Inspire software. The topology optimisation algorithm is used to minimise the weight of the caliper without compromising the stiffness. The structural analysis is also carried out on the Altair Inspire. The caliper is also tested for fatigue failure using Ansys.

Turbocharging of diesel engines have undergone various phases of technological advancements proving merits with engine performance. Since VGTs are finding their applications in many automotive engines, it is also crucial on finding out ways to extract maximum benefits from the system. Pneumatic actuated VGTs control the vanes positioning with the help of mechanical linkages and don’t prove good in transient response with relatively slower boost build up. The electronic controlled VGT operates with the aid of DC motor which is linked to the engine management system. The position sensor senses the current position of the actuator which is controlled by the engine management system for delivering the desired boost pressure. The eVGT system thus provides very quick response and accurate control of boost pressure in all the vehicle driving conditions.

In this work, Calculations and design of connecting rod of IC engine is performed in innovative way. Calculation point of view, Con rod is the utmost critical component of IC Engine as it is the part which translates reciprocating forces into rotary forces and thus creates unbalance in engine. From the functionality point of view, connecting rod must have the higher inertia at the lowest weight. Different forces acting on con rod are: - Peak combustion pressure, inertia force of reciprocating masses, Weight of Reciprocating parts and frictional forces due to cylinder wall thrust. It experiences complex forces of compression and tensile in cyclic manner, which repeats after each 720 (in case of 4 stroke) or 360 (in case of 2 stroke) phase of degree. Hence, the design calculations are analyzed for the axial compressive as well as axial tensile loads considering the fatigue strength of con rod. This literature computes the required size and strength in the critical areas of failure.

EGR flow within individual cylinder as per requirement has a great importance which controls the performance and emissions of the diesel engine. The work presented here, elaborates the mixing process of EGR in the manifold with the fresh charge entering into intake manifold and then into cylinder. The study is carried on our three-cylinder diesel engine. For the simulation of such highly pulsating flow, the boundary conditions were generated from 1D model & in the back end the 3D CFD is used to solve the EGR mixing in a transient phase. The mixing at each cylinder port is evaluated using the Air and CO2 mass fraction at outlet of each intake port. Being a transient nature of valve operation, the EGR distribution within the manifold observed stabilized in 9 cycles. It was observed that the flow pulsations at the EGR inlet have large influence on the EGR distribution.