A model based approach for determining data quality metrics in combustion pressure measurement. A study into a quantative based improvement in data quality
AuthorRogers, David R.
SupervisorEbrahimi, Kambiz M.
Mason, Byron A.
KeywordCombustion measurement; Internal combustion engine; Data quality; Result calculation; Simulation; Modelling; Error simulation; Combustion pressure; Internal combustion
The University of Bradford theses are licenced under a Creative Commons Licence.
InstitutionUniversity of Bradford
DepartmentFaculty of Engineering and Informatics
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AbstractThis thesis details a process for the development of reliable metrics that could be used to assess the quality of combustion pressure measurement data - important data used in the development of internal combustion engines. The approach that was employed in this study was a model based technique, in conjunction with a simulation environment - producing data based models from a number of strategically defined measurement points. A simulation environment was used to generate error data sets, from which models of calculated result responses were built. This data was then analysed to determine the results with the best response to error stimulation. The methodology developed allows a rapid prototyping phase where newly developed result calculations may be simulated, tested and evaluated quickly and efficiently. Adopting these newly developed processes and procedures, allowed an effective evaluation of several groups of result classifications, with respect to the major sources of error encountered in typical combustion measurement procedures. In summary, the output gained from this work was that certain result groups could be stated as having an unreliable response to error simulation and could therefore be discounted quickly. These results were clearly identifiable from the data and hence, for the given errors, alternative methods to identify the error sources are proposed within this thesis. However, other results had a predictable response to certain error stimuli, hence; it was feasible to state the possibility of using these results in data quality assessment, or at least establishing any boundaries surrounding their application for this usage. Interactions in responses were also clearly visible using the model based sensitivity analysis as proposed. The output of this work provides a solid foundation of information from which further work and investigation would be feasible, in order to achieve an ultimate goal of a full set of metrics from which combustion data quality could be accurately and objectively assessed.
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The mechanics of valve cooling in internal-combustion engines. Investigation into the effect of VSI on the heat flow from valves towards the cooling jacket.Rosala, George F.; Wright, Steve; Abdel-Fattah, Yahia (University of BradfordSchool of Engineering Design and Technology, 2010-06-14)Controlling the temperature of the exhaust valves is paramount for proper functioning of engines and for the long lifespan of valve train components. The majority of the heat outflow from the valve takes place along the valve-seat-cylinder head-coolant thermal path which is significantly influenced by the thermal contact resistance (TCR) present at the valve/seat and seat/head interfaces. A test rig facility and experimental procedure were successfully developed to assess the effect of the valve/seat and seat/head interfaces on heat outflow from the valve, in particular the effects of the valve/seat interface geometry, seat insert assembly method, i.e. press or shrink fit, and seat insert metallic coating on the operating temperature of the valve. The results of tests have shown that the degree of the valve-seat geometric conformity is more significant than the thermal conductivity of the insert: for low conforming assemblies, the mean valve head temperature recorded during tests on copper-infiltrated insert seats was higher than that recorded during tests on noninfiltrated seats of higher conformance. The effect of the insert-cylinder head assembly method, i.e. shrink-fitted versus press-fitted inserts, has proved negligible: results have shown insignificant valve head temperature variations, for both tin-coated and uncoated inserts. On the other hand, coating the seat inserts with a layer of tin (20-22¿m) reduced the mean valve head temperature by approximately 15°C as measured during tests on uncoated seats. The analysis of the valve/seat and seat/head interfaces has indicated that the surface asperities of the softer metal in contact would undergo plastic deformation. Suitable thermal contact conductance (TCC) models, available in the public domain, were used to evaluate the conductance for the valve/seat and seat/cylinder head interfaces. Finally, a FE thermal model of the test rig has been developed with a view to assess the quality of the calculated TCC values for the valve/seat and seat/head interfaces. The results of the thermal analysis have shown that predicted temperatures at chosen control points agree with those measured during tests on thermometric seats with an acceptable level of accuracy, proving the effectiveness of the used TCC models.
Distinguishing wild ruminant lipids by gas chromatography/combustion/isotope ratio mass spectrometryCraig, O.E.; Allen, R.B.; Thompson, A.; Stevens, R.E.; Steele, Valerie J.; Heron, Carl P. (2012)RATIONALE: The carbon isotopic characterisation of ruminant lipids associated with ceramic vessels has been crucial for elucidating the origins and changing nature of pastoral economies. delta(13)C values of fatty acids extracted from potsherds are commonly compared with those from the dairy and carcass fats of modern domesticated animals to determine vessel use. However, the processing of wild ruminant products in pottery, such as deer, is rarely considered despite the presence of several different species on many prehistoric sites. To address this issue, the carbon isotope range of fatty acids from a number of red deer (Cervus elaphus) tissues, a species commonly encountered in the European archaeological record, was investigated. METHODS: Lipids were extracted from 10 modern red deer tissues obtained from the Slowinski National Park (Poland). Fatty acids were fractionated, methylated and analysed by gas chromatography/combustion/isotope ratio mass spectrometry (GCCIRMS). The delta(13)C values of n-octadecanoic acid and n-hexadecanoic acid, and the difference between these values (Delta(13)C), were compared with those from previously published ruminant fats. RESULTS: Nine of the ten deer carcass fats measured have Delta(13)C values of less than -3.3 per thousand, the threshold previously used for classifying dairy products. Despite considerable overlap, dairy fats from domesticated ruminants with Delta(13)C values less than -4.3 per thousand are still distinguishable. CONCLUSIONS: The finding has implications for evaluating pottery use and early pastoralism. The processing of deer tissues and our revised criteria should be considered, especially where there is other archaeological evidence for their consumption.
Simulating the Influence of Injection Timing, Premixed Ratio, and Inlet Temperature on Natural Gas / Diesel Dual-Fuel HCCI Combustion in a Diesel EngineGhomashi, Hossein; Olley, Peter; Mason, Byron A.; Ebrahimi, Kambiz M. (2015)Dual-fuel HCCI engines allow a relatively small quantity of diesel fuel to be used to ignite a variety of fuels such as natural gas or methane in HCCI mode. The gaseous fuel is mixed with the incoming air, and diesel fuel is sprayed into the cylinder by direct injection. Mathematical modelling is used to investigate the effects of parameters such as premixed ratio (fuel ratio) and pilot fuel injection timing on combustion of a dual-fuel HCCI engines. A CFD package is used with AVL FIRE software to simulate dual-fuel HCCI combustion in detail. The results establish a suitable range of premixed ratio and liquid fuel injection timing for low levels of NOx, CO and HC emissions along with a reliable and efficient combustion. Dual-fuel HCCI mode can increase NOx emission with lower premixed ratios in comparison to normal HCCI engines, but it is shown that the NOx emission reduces above a certain level of the premixed ratio. Due to the requirement of homogenous mixing of liquid fuel with air, the liquid fuel injection is earlier than for diesel engines. It is shown that, with careful control of parameters, dual-fuel HCCI engines have lower emissions in comparison with conventional engines.