Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Microfiche copy available in Archives and Engineering. / Includes bibliographical references. / by Julian A. LoRusso. / M.S.

Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Includes bibliographical references. / M.S.

Typescript. / Digitized by Kansas Correctional Industries

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Stephen Gregory Poulos. / M.S.

Government legislation on particulate matter (PM) and oxides of nitrogen (NOX) emissions have become increasingly stringent over the past decades. Future projections have led to internal combustion (IC)engine developers exploring advanced combustion technologies which may replace or supplement current state of the art systems. Advanced combustion technologies such as Low Temperature Combustion (LTC) cover a broad series of mechanisms that seek to attain in-cylinder Equivalence ratio (f) - Temperature (T) combinations during combustion which lead to acceptable emissions of exhaust PM and NOX. These are generally achieved by a combination of EGR dilution and extended ignition delays for mixture preparation. Another common feature of LTC is the poor combustion efficiency due to severe requirements placed on mixture quality as lower temperatures and oxygen concentrations reduce local ignitability limits. Therefore, a significant amount of work on LTC is centred around understanding the spatial and temporal development of inadequately prepared mixtures during LTC. The investigations presented in this thesis are expected to contribute to this body of work as they are predicated on the hypothesis that current mixture preparation methods are insufficiently adapted to conditions present in LTC combustion modes.

This report is a theoretical study of the potential an ICE (internal combustion engine) has when combined with the load case of a high-performance series hybrid drivetrain. It breaks down the different theoretical variables that affect engine efficiency and possible limitations that arise. The report then moves on to specifying the current emerging technologies associated with increasing engine efficiency such as active, and passive prechamber ignition. The different technologies strengths and weaknesses were then compared with each other to decide the best strategies and technologies to move forward with. Here efficiency gain potential was compared to price, performance and complexity. The different technologies were compared in two separate steps firstly the technologies were compared individually, then the best systems were compared to different engine configurations in an iterative process. Here the most balanced solution was found using a passive prechamber to allow higher compression ratio while allowing better timing control. This was later combined with a Miller cycle strategy resulting in a theoretical efficiency improvement of ~8%. This would potentially allow a high performance vehicle to match a midrange diesel engine in fuel economy.

This thesis focuses on the factors which lead to off-shore manufacture of Australian inventions. It establishes this phenomenon as a problem, both in terms of its incidence in the post-war period, and in the strategic importance of innovative activity to economic growth. The thesis utilises a case study approach and concentrates on the experiences of one company, the Orbital Engine Corporation (Orbital). In 1989 Ralph Sarich, inventor of the Orbital Combustion Process (OCP) engine and founder of Orbital, signed an agreement with the Michigan state government to manufacture the engine in the United States of America (USA), in preference to several alternative sites in Australia and overseas. This occurred in the context of Orbital actively pursuing assistance from the Australian government to secure local production. The research question is: Why did Orbital decide to manufacture its engine invention ofshore? A multi-disciplinary approach to this question is adopted. Three different conceptual frameworks are employed: industrial organisation theory, market failure theory and policy network theory. The analysis is not structured around a pre-existing hypothesis; instead, the aim is to generate potential explanations for more rigorous testing by subsequent researchers. The thesis concludes that, in terms of industrial organisation theory, the decision to manufacture OCP engines off-shore was a function of the poor quality of the Australian industrial context and the failure by those seeking assistance from the Commonwealth government to stress Orbital's status as an exemplary enterprise in Australian industry. Market failure theory indicated that offshore production of the OCP engine was made more likely by the suboptimal operation of the price mechanism, the neglect of market failure arguments by those supporting local production of the engine and 'government failure'. Policy network theory explained Orbital's decision as the result of: ineffective employment of negotiation tactics by proponents of the engine's domestic manufacture; and the chaotic nature of negotiations which allowed certain personal and ideological prejudices to dominate the issue resolution process. It is shown that some or all of these explanations underlie a number of other examples where Australian inventions have been manufactured offshore. In commenting on policy implications, the thesis points to the economic potential of the Orbital invention and the value of interventionist industry policy. The thesis identifies a number of actions which might be taken to lower the incidence of foreign manufacture of Australian inventions. Further research is necessary to determine the relative importance of the various factors which are identified as leading to offshore production. In addition, there remains a particularly crucial need to improve the social efficiency of existing cost-benefit techniques employed by government policy-makers and commercial analysts.

A Computational Fluid Dynamics (CFD) simulation of the Bishop Rotary Valve (BRV) engine is developed. The simulation used an existing commercial CFD code, CFX 4.3, with a number of new routines written to allow it to simulate the conditions and motions involved in an internal combustion engine. The code is extensively validated using results from other researchers, and several new validations are performed to directly validate the code for simulating internal combustion engine flows. Firstly, tumble vortex breakdown during the compression stroke of a square piston model engine is modelled. The results of the simulation are validated against published high quality experimental data. Both two- and three-dimensional models are tested, using the k-e and Reynolds stress turbulence models. The Reynolds stress turbulence model simulations successfully predicted the tumble break down process during the compression stroke. A simple three-dimensional Large Eddy Simulation model is also presented. The numerical simulation is then applied to the BRV engine. An in-cylinder flow field not previously described is discovered, created by the unique combustion chamber shape of the BRV engine. The flow field is not adequately described by the traditional descriptions of engine flows, being squish, swirl and tumble. The new flow structure is named 'dual cross tumble', and is characterised by two counter-rotating vortices in the cross tumble plane on either side of the inlet air jet. Analysis of the dual tumble structure indicates that it is most beneficial in high bore to stroke ratio engines. This flow structure has been predicted or visualised by a small number of previous researchers, however no published research has recognised its significance or potential benefits. The validated code is then used to predict the effect of modifying the valve cross sectional area, the effect of the inlet manifold wave, the effect of heat transfer from the inlet manifold walls, the effect of bore to stroke ratio, and the effect of engine speed. This work presents a numerical simulation of a new rotary valve engine technology. This opens up a whole new area of engine aerodynamics research as no detailed examination of the flows in a rotary valve engine have been presented previously. In the process, it discovers a new compression stroke turbulence generation mechanism, 'dual cross tumble', which offers the potential of performance levels not possible using poppet valve engines.

In this work CFD was used to simulate the flow through a novel valve design for internal combustion engines. CFD is numerical method for simulating the behaviour of systems involving flow processes. A FEM was used for solving the equations. Literature on the topic was studied to gain an understanding of the performance limiters on the Internal combustion engine. This understanding was used to set up models that better would mimic physical phenomena compared to previous studies. The models gave plausible results as to fluid velocities and in-cylinder flow patterns. Comsol Multiphysics 4.1 was used for the computations.

The mean value engine model (MVEM) is a mathematical model derived from basic physical principles such as conservation of mass and energy equations. Although the MVEM is based on some simplified assumptions and time averaged combustion engine parameters, it models the engine with a reasonable approximation and gives a satisfactory amount of information about the physics of the fluid energy passing through an engine system. MVEM can predict an engine’s main external variables such as crankshaft speed and manifold pressure, and important internal variables, such as volumetric and thermal efficiencies. Usually, the differential equations used in MVEM will predict fuel film flow, manifold pressure, and crankshaft speed. Because of its simplicity and short simulation time, the MVEM is widely used for engine control development. A mean value engine based on mathematical and parametric equations has recently been developed in the new MapleSim software. The model consists of three main components: the throttle body, the manifold, and the engine. The new MVEM uses combinations of causal and acausal components along with lookup tables and parametric equations. Adjusting the parameters allows the model to be used for new engines of interest. The model is forward-looking and so benefits from both Maple’s powerful mathematical tool and Modelica’s modern equation-based language. A set of throttle angle and mass flow data is used to find the throttle angle function, and to validate the throttle mass flow rates obtained from the model and the experiment.