Search results for "COMBUSTION"
showing 10 items of 232 documents
Propellant non-steady burning effects on controllable solid rocket motor internal ballistics
2009
An analysis of the unsteady non-linear behavior of the controllable solid propellant rocket motor (CSRM) consequent to rapid and relevant nozzle operation is presented. The study includes a development of a non-linear unsteady combustion model able to handle relevant and rapid chamber pressure changes typical of CSRMs. The CSRM nonlinear unsteady model is implemented according to a main solver - sub models architecture and uses different time scales. The formulation of the combustion gas mass flow rate is developed considering the propellant density, the unsteady combustion, the regression of the combustion surface and the outflow through the variable nozzle. The grain surface involved in t…
Further Experiments on the Effect of Bulk In-Cylinder Temperature in the Pressurized Motoring Setup Using Argon Mixtures
2020
Mechanical friction and heat transfer in internal combustion engines have long been studied through both experimental and numerical simulation. This publication presents a continuation study on a Pressurized Motoring setup, which was presented in SAE paper 2018-01-0121 and found to offer robust measurements at relatively low investment and running cost. Apart from the limitation that the peak in-cylinder pressure occurs around 1 DegCA BTDC, the pressurized motoring method is often criticized on the fact that the gas temperatures in motoring are much lower than that in fired engines, hence might reflect in a different FMEP measurement. In the work presented in SAE paper 2019-01-0930, Argon w…
An Experimental Study of In-Cylinder Heat Transfer from a Pressurized Motored Engine with Varying Peak Bulk Gas Temperatures
2022
The variation of in-cylinder heat transfer with parameters such as engine speed, air-to-fuel ratio, coolant temperature and compression ratio were frequently studied in classical research. These experimentally-obtained relationships are important for improving in-cylinder heat transfer models, essential in developing CO2 reducing strategies. In this publication, a 2.0 liter compression ignition engine was tested in the pressurized motored configuration. This developed experimental setup allowed testing of the engine at speeds ranging between 1400 rpm and 3000 rpm, with peak in-cylinder gas pressures from 40 bar to 100 bar. The engine was motored using different gas compositions chosen speci…
An Effective Method to Model the Combustion Process in Spark Ignition Engines
2022
A numerical simulation is a fundamental tool in the design and optimization procedure of an Internal Combustion (IC) engine; since combustion is the process that mostly influences the engine performance, efficiency and emissions, an effective combustion submodel is fundamental. A simple, nonpredictive way to simulate the combustion evolution is to implement a mathematical function that reproduces the mass fraction burned (MFB) profile that is characterized by a sigmoidal trend; the most used for this purpose is the Wiebe function. In this article the authors propose a different mathematical model, a Dose-Response (DR) type function that shows some benefits when compared to the Wiebe functio…
Simulation Study on the Use of Argon Mixtures in the Pressurized Motored Engine for Friction Determination
2020
Mechanical friction and heat transfer in internal combustion engines are two highly researched topics, due to their importance on the mechanical and thermal efficiencies of the engine. Despite the research efforts that were done throughout the years on both these subjects, engine modeling is still somewhat limited by the use of sub-models which do not fully represent the phenomena happening in the engine. Developing new models require experimental data which is accurate, repeatable and which covers wide range of operation. In SAE 2018-01-0121, the conventional pressurized motored method was investigated and compared with other friction determination methods. The pressurized motored method p…
Realistic Steady State Performance of an Electric Turbo-Compound Engine for Hybrid Propulsion System
2022
The efficiency of Hybrid Electric Vehicles (HEVs) may be substantially increased if the unexpanded exhaust gas energy is efficiently recovered and employed for vehicle propulsion. This can be accomplished employing a properly designed exhaust gas turbine connected to a suitable generator whose output electric energy is stored in the vehicle storage system; a new hybrid propulsion system is hence delineated, where the power delivered by the main engine is combined to the power produced by the exhaust gas turbogenerator: previous studies, carried out under some simplifying assumptions, showed potential vehicle efficiency increments up to 15% with respect to a traditional turbocharged engine. …
Nanocomposites of epoxy resin with graphene nanoplates and exfoliated graphite: Synthesis and electrical properties
2014
Nanocomposites are nowadays one of the most promising materials. Among different fillers, e.g. carbon nanotubes and silicon carbide nanowires (NWSiC), already used with epoxy resin matrices, graphene exfoliated graphite (EG) and graphene nanoplates have some characteristics that make them unique for electromagnetic shielding materials. However, there is still an unresolved problem of proper dispersion that will ensure the homogeneity of samples. To overcome this drawback, inorganic fibres were proposed. An amount of 0.25 phr (parts per hundred; filler content presented as wt.% of the whole polymeric matrix) NWSiC, added to the EG 1 phr/epoxy resin sample, efficiently prevents filler agglome…
Lo strano caso di Cornelia Bandi (1731). Un dibattito sulla «combustione spontanea» nel XVIII secolo
2014
Il saggio ricostruisce il dibattito di matrice medico-scientifica scaturito da un caso di cronaca avvenuto a Cesena nel 1731, quando il cadavere della nobildonna Cornelia Bandi veniva trovato in stato di parziale incenerimento in una camera da letto che non presentava tracce alcune di rogo. Emergeva nel mondo scientifico ed erudito dell’epoca un dibattito che coinvolgeva alcuni dei personaggi più influenti della cultura coeva, da Giuseppe Bianchini a Scipione Maffei e Ludovico Antonio Muratori, sino a Immanuel Kant, e che più avanti, in un contesto culturale profondamente mutato, raccoglieva l’interesse di Giacomo Leopardi e Charles Dickens. Appare con tutta evidenza la differenza tra la pe…
Combustion behavior of kraft black liquor droplets from hot water pretreated hardwood and softwood chips
2016
This paper describes the combustion behavior of birch and spruce kraft black liquors obtained from an integrated forest biorefinery concept in which a hot water extraction of chips was performed before pulping. This pretreatment, aiming mainly at the recovery of various hemicellulose-derived materials, increased the concentrations of lignin and hydroxy acids in black liquors, compared with those in the reference black liquors without any process modification. On the other hand, the pretreatment decreased the concentrations of volatile acids and other organics (extractives and hemicellulose residues). Because of these characteristic changes, the total burning times (pyrolysis time plus char …
WAVES PROPAGATION AND LIQUID ALUMINUM PARTICLE INJECTION IN SOLID ROCKET MOTORS
2013
A method to determine the injection of aluminium particles from the solid propellant burning surface to the core of the chamber in the presence of an acoustic wave field is developed and aluminum-droplet effects on propagation of acoustic waves in the flow of a solid rocket motor are analysed. Changes of the multiphase flow compressibility are calculated by taking into account both the translational and the pulsational motions of the aluminum droplets in consequence of the acoustic waves.