A reinforcement learning-based method for pressure distribution control in engine combustion chambers

The article presents an overview of the chemical principle of anti-detonation additives, which are now widely used in gasolines. The most probable reactions that occur with hydrocarbons in the fuel-air mixture when it enters the combustion chamber of an internal combustion engine are considered. These reactions are mainly represented by cracking with the formation of active radicals, which in turn enter into the oxidation reaction with oxygen. Formed in this way, hydroperoxides take part in chain oxidation reactions, which contributes to the effect of detonation combustion of the fuel-air mixture. In view of this reaction, it is proposed to use 1,3-diphenyltriazene, which belongs to the class of diazocompounds, as an anti-detonation additive for motor gasolines. The principle of anti-detonation effect of this substance is, first of all, the possibility of its thermal decomposition in the temperature range 130-160 °C. In this case, nitrogen, phenyl and aniline radicals will be formed. The phenyl radical, which is one of the most unstable particles, due to its increased reactivity reacts instantly with the most active fuel radicals: atomic hydrogen; methyl and hydroxyl radicals. At the same time, there is a high probability of formation of molecular hydrogen, toluene and phenol among the products of such interactions. These are stable compounds that are not able to continue and maintain the chain oxidation reactions that occur during the combustion of the fuel-air mixture in the combustion chamber of the engine. Thus, in the reaction zone with the direct participation of phenyl radicals there is a decrease in the concentration of radicals initiating chain oxidative reactions, which leads to chain breakage. Also, a very positive aspect of the use of 1,3-diphenyltriazene is that it can be used in compositions with alcohols or with methyl tert-butyl ether in straight-run gasoline fractions of oil, their mixtures with the fractions of the catalytic cracking and of the riforming. The using of the proposed additive in the composition of gasoline fully meets the requirements of the environmental safety standard Euro-5. Key words: gasoline, detonation resistance, additives, 1,3-diphenyltriazene, cracking, oxidation, radicals, internal combustion engine Corresponding author A. B. Grigorov, e-mail:grigorovandrey@ukr.net

In the present work, a convergent–divergent nozzle with a multi‐inlet combustion chamber of a rocket engine is numerically investigated to precisely understand the flow dynamics and variation of flow properties like pressure, temperature, and velocity distribution. The work also deals with a modified combustion chamber having multiple inlets. According to the entry conditions, when the propellants enter the combustion chamber, they are burning due to high velocity and temperature. Then there is a rapid increase in temperature and pressure in the combustion chamber, and afterward, they decrease over the nozzle's length. In this study, three configurations have been prepared in the design modular of ANSYS, a combined setup of the convergent–divergent nozzle with a combustion chamber with four inlets, six inlets, and one with increased combustion chamber length called a modified combustion chamber configuration. In this analysis, an investigation is performed to see the effect of multi‐inlet and increased length of the combustion chamber on the convergent–divergent nozzle's exit velocity. The results show that the configuration with six inlets modified combustion chamber has a 26.3% increase in velocity than six inlets and 38.6% higher exit velocity than four inlets convergent–divergent nozzle of the rocket engine.

An experimental study on quenching crevice widths in the combustion chamber of a spark-ignition engine

The future of automobile internal combustion (IC) engine facing twin challenges due to emission norms and improving engine performance. Hence it is very important to identify some technique to reduce the emission level and also to improve the engine performance. Catalytic coating is one of the most suitable techniques for reduction of pollution level and increase the engine efficiency. In this paper, the investigations carried out in the single cylinder catalytic coated four stroke spark ignition (SI) engine is discussed in detail. The engine combustion chamber and piston crown were coated by copper (catalyst). The performance of catalytic coated engine various parameters such as torque, brake power at different engine speed conditions measured by using two wheeler chassis dynamometer. In this investigation the comparative study also were carried out for copper coated engine with conventional (Un-coated) SI engine and the results showed that copper coated engine has significant reduction of the carbon monoxide (CO), Hydrocarbon (HC), and Carbon dioxide (CO2) level compare to conventional engine (uncoated) emission levels.The future of automobile internal combustion (IC) engine facing twin challenges due to emission norms and improving engine performance. Hence it is very important to identify some technique to reduce the emission level and also to improve the engine performance. Catalytic coating is one of the most suitable techniques for reduction of pollution level and increase the engine efficiency. In this paper, the investigations carried out in the single cylinder catalytic coated four stroke spark ignition (SI) engine is discussed in detail. The engine combustion chamber and piston crown were coated by copper (catalyst). The performance of catalytic coated engine various parameters such as torque, brake power at different engine speed conditions measured by using two wheeler chassis dynamometer. In this investigation the comparative study also were carried out for copper coated engine with conventional (Un-coated) SI engine and the results showed that copper coated engine has significant reduction of the carbon mon...

Combustion instability in rocket engines is accompanied by large-amplitude pressure fluctuations in the combustion chamber and (or) intense vibration of the load-bearing structural elements. Unstable operation leads to a decrease in thrust, specific impulse, a decrease in engine life, a violation of the normal operation of vibration-sensitive flight control system equipment. The study considers a method for determining the frequencies of the first and second tone natural resonances of the longitudinal mode of acoustic vibrations in the combustion chambers of solid propulsion engines. The gas path of the combustion chamber is divided into homogeneous sections, for which solutions of the wave equation are presented. To determine the natural frequencies and the distribution of vibrational pressures and velocities, the method of "stitching" acoustic fields at the boundaries of cavities was applied. In the course of the study, to determine the decrement from natural perturbations, the following methods were used: spectral, correlation, amplitude, and instantaneous period method. In the study, vibrations of a certain frequency in a given range were excited using an electrodynamic emitter. To obtain the acoustic characteristics of the camera at various moments of engine operation, experiments were carried out with several charge models having different sizes. The solution of the wave equation in the form of standing waves was considered. In addition, the study results present a description of the experimental setup, in particular, the distribution of the oscillatory pressure in the chamber gas cavity (according to the calculated data). In the course of the study, an algorithm was developed for calculating and experimentally determining the acoustic characteristics of the combustion chambers of solid propulsion engines.

THE LIGHT "KNIFE" METHOD FOR STUDYING AERODYNAMIC PROCESSES IN THE COMBUSTION CHAMBERS OF DIESEL ENGINES V. M. Boiko, O. G. Kudelin, O. N. Lebedev, G. E. Lushchaev, and A. A. Plesovskikh UDC 621.43-44 It is well known that in order to optimize the working process of internal combustion engines (ICEs) it is necessary to know the laws governing the motion of air in the combustion chambers (CCs) throughout the entire period of compression as a preparatory stage before mix- ing and burning of the fuel. This question has never been completely studied, though more than one generation of investigators in different countries has studied it intensively [1-5 and others]. In the opinion of many of these investigators the question can be reduced to two problems that reflect the main difficulty in the experimenal study: choice of measure- ment methods and organization of the optical access to the CC. Among the modern methods for performing measurements the methods based on contact-free optical principles must be singled out. Thus, compared with the traditional contact methods [6, 7], the contact-free methods inherently have a high accuracy, which is especially impor- tant, and the compression process is not disturbed. For this reason they can be used to study complicated aerodynamic processes in the CCs of ICEs. The light "knife" method stands out among the methods used in practice [8]. In this work this method is chosen because it has significant advantages over the other methods. The realization of optical access directly into the CC, situated in the piston, is an extremely difficult technical problem. We shall study the traditional methods for solving this problem for the following examples. In [9] a model of a piston whose bottom was made in the form of a transparent insert and the skirt, was equipped with a cut is described. A mirror was rigidly fastened inside the piston in the zone of the cut at an angle to its longi- tudinal axis. The cylinder contained an optically transparent window, opposite which a mo- tion picture camera was placed. The errors introduced by the refraction of the light rays on the curved surface as well as the great technical difficulties in preparing the apparatus make it difficult to use this model for studying the aerodynamic qualities of semidivided CC in diesel engines.

The expediency of using vehicles of liquefied petroleum gas as a motor fuel, as com-pared with traditional liquid motor fuels, in particular with diesel fuel, is shown. The advantages of converting diesel engines into gas ICEs with forced ignition with respect to conversion into gas diesel engines are substantiated. The analysis of methods for reducing the compression ratio in diesel engines when converting them into gas ICEs with forced ignition has been carried out. It is shown that for converting diesel engines into gas ICEs with forced ignition, it is advisable to use the Otto thermo-dynamic cycle with a decrease in the geometric degree of compression. The choice is grounded and an open combustion chamber in the form of an inverted axisymmetric “truncated cone” is developed. The proposed shape of the combustion chamber of a gas internal combustion engine for operation in the LPG reduces the geometric compression ratio of D-120 and D-144 diesel engines with an unseparated spherical combustion chamber, which reduces the geometric compression ratio from ε = 16,5 to ε = 9,4. The developed form of the combustion chamber allows the new diesel pistons or diesel pistons which are in operation to be in operation to be refined, instead of making special new gas pistons and to reduce the geometric compression ratio of diesel engines only by increasing the combustion chamber volume in the piston. This method of reducing the geometric degree of compression using conventional lathes is the most technologically advanced and cheap, as well as the least time consuming. Keywords: self-propelled chassis SSh-2540, wheeled tractors, diesel engines D-120 and D-144, gas engine with forced ignition, liquefied petroleum gas (LPG), compression ratio of the internal com-bustion engine, vehicles operating in the LPG.

The objective of this study is the thermal investigation of a typical spark-ignition (SI) engine combustion chamber with particular focus in determination of the locations where the heat flux and heat transfer coefficient are highest. This subject is an important key for some design purposes especially thermal loading of the piston and cylinder head. To this end, CFD simulation using the KIVA-3V CFD code on a PC platform for flow, combustion, and heat transfer in a typical SI engine has been performed. Some results including the temporal variation of the area-averaged heat flux and heat transfer coefficient on the piston, combustion chamber, and cylinder wall are presented. Moreover, the temporal variation of the local heat transfer coefficient and heat flux along a centerline on the piston as well as a few locations on the combustion chamber wall are shown. The investigation reveals that during the combustion period, the heat flux and heat transfer coefficient vary substantially in space and time due to the transient nature of the flame propagation. For example, during the early stages of the flame impingement on the wall, the heat flux undergoes a rapid increase by as much as around 10 times the preimpingement level. In other words, the initial rise of the heat flux at any location is related to the time of the flame arrival at that location.

The purpose of the work is to identify complex transient heat flow paths in the combustion chamber of engine, significantly improve the models of diesel engine heat flow, and study the effect of aluminum oxide coating by the galvanic plasma method on short-term and long-term reactions of the piston head. The analysis of operation of aluminum alloy coated diesel engine piston is carried out using a modified quasi -steady method and a finite element method. A thermodynamic analysis is presented using energy and state equations with corresponding gas heat transfer. Time-dependent boundary conditions are set on the gas-blown surfaces of 2D finite element transition models of combustion chamber components. It is shown that this methodology can reveal complex transient paths of the heat flow in engine combustion chambers and distribution details of heat losses in various cooling media. Numerical simulation has shown that the maximum temperature increase relative to the uncoated piston is 64.3% for the coating thickness of 0.13 mm. Tests have shown that the coatings can endure up to 280 thermal cycles. It is found out that predictions of numerical simulation are in good agreement with the results of experiments conducted with repaired pistons. The experimental operation of Cummins КТА 38 engines at Chernogorsk and Vostochno-Beysk coal mines has shown that the engine equipped after repair with the piston coated with aluminum applied by the galvanic plasma method has been in operation for 2 years and 3 months, whereas its set overhaul period is 18,000 hours. Therefore, the proposed methodology allows to reduce temperature variations in the piston and, thereby increase the service life of engine pistons coated with the use of the thermal barrier coating technology.

The combustion chamber is one of the main components that determine the energy and mass characteristics of the propulsion system. A detailed description of the combustion chambers of some model engines running on kerosene is given. The results of fire tests and numerical studies of combustion chambers of model small-sized gas turbine engines are considered. To qualitatively compare the results of calculations with the data of a physical experiment, annealed colors are used. Based on the results of the research, a map of tem perature distribution on the walls of the combustion chamber was compiled. The internal and external surfaces of the combustion chamber are unevenly colored with tarnished colors. This coloring is a consequence of non-uniform distributions of temperature and concentration of various components of combustion products, and also indicates the formation of a spatial flow in the combustion chamber.

The paper formulates the issue of development of experimental base with noninvasive optical-electronic tools for control of combustion in a combustion chamber of gas turbine engine. The design and specifications of a pilot sample of optronic system are explained; this noninvasive system was created in the framework of project of development of main critical technologies for designing of aviation gas turbine engine PD-14. The testbench run data are presented.

In various countries around the world, the emissions of NOX from petrol/gasoline and diesel engine vehicles are restricted by legislation. NOX is produced in the combustion chamber of engines at high temperatures and high pressure. One of the most promising technology for effective control of NOX emissions is Exhaust Gas Recirculation (EGR) and now most modern engines require exhaust gas recirculation to meet emission standards. EGR lowers the presence of oxygen concentration and burn temperature in the combustion chamber and hence controls the NOx. The experimentation was carried out on a 5.2 kW of single cylinder four stroke direct injection diesel engines in computerized mode to investigate the performance, emissions and combustion parameters at different EGR ratios (10, 20 and 30%). From the results, O2, NOX and exhaust temperatures are found to be reduced whereas HC and CO emissions are increased as the EGR concentration increases.

<div class="htmlview paragraph">Experiments and modeling of a spray impinged onto a cavity wall of a simulated piston were performed under simulated diesel engine conditions (pressure and density) at an ambient temperature. The diesel fuel was delivered from a Bosch-type injection pump to a single-hole nozzle, the hole being drilled in the same direction as the original five-hole nozzle. The fuel was injected into a high-pressure bomb in which an engine combustion chamber, composed of a piston, a cylinder head and a cylinder liner, was installed. Distributions of the spray impinged on the simulated combustion chamber were observed from various directions while changing some of the experimental parameters, such as combustion chamber shape, nozzle projection and top-clearance. High-speed photography was used in the constant volume bomb to examine the effect of these parameters on the spray distributions. The spray distributions obtained in the simulated combustion chamber are compared to the distributions calculated by a spray model based on a multi-package spray model.</div>

The existence of deposits in the combustion chamber will affect the performance and emissions of the engine, and this will not be avoided using petroleum fuels and lubricating oils. This makes it necessary to study the formation, composition, structure and influential factors of the deposit, which will provide a basis for reducing deposit on the engine. This article reviews experimental studies on the formation of deposits in engine combustion chambers, as an effect of the use of a mixture of biodiesel on diesel fuel, with an emphasis on the composition of deposits, the influence of temperature, and study methods. This study is based on a report by researchers who conducted various experiments with various types of biodiesel and various methods to obtain deposit formation characteristics in mixing biodiesel. The study of deposit formation with several types of newly developed fuels was also included. The mechanism of deposit structure analysis in various ways is also explained. Based on the results of the study, it shows that deposits can be formed or can be determined depending on the nature of the fuel. Furthermore, about the deposit research approach to its chemical composition and physical structure is taken. Finally, regarding the formation of deposits in diesel engines, the composition of deposits and factors that influence deposit formation, such as engine type, fuel type, are mentioned through experimental studies on machines.

Although premixed charge compression ignition (PCCI) combustion engines are praised for potentially high efficiency and clean exhaust, experimental engines built to date emit more hydrocarbons (HCs) and carbon monoxide (CO) than the conventional machines. These compounds are not only strictly controlled components of the exhaust gas of road vehicles but are also an energy loss indicator. The prime objective of this study was to investigate the major sources of the HCs formed in the combustion chamber of an experimental PCCI engine in order to suggest some effective technologies for HC reduction. In this study, to explore the dominant sources of HC emissions in both operation modes, a single cylinder engine was prepared such that it could operate using either conventional diesel combustion or PCCI combustion. Specifically, the contributions of the top-ring crevice volume in the combustion chamber and the bulk quenching of the lean mixture were investigated. To understand the influence of the shape and magnitude of the crevice on HC emissions, the engine was operated with 12 specially prepared pistons with different top-ring crevices installed one after another. The engine emitted proportionally more HCs as the depth of the crevice increased as long as the width remained narrower than the prevailing quench distance. The top-ring-crevice-originated exhaust HCs comprised approximately 31% of the total HC emissions in the baseline condition. In a series of tests to estimate the effects of bulk quench on exhaust HC emissions, intake air was heated from 300K to 400K in steps of 25K. With the intake air heated, HC and CO emissions decreased with a gradually diminishing rate to zero at 375K. In conclusion, the most dominant sources of HC emissions in PCCI engines were the crevice volumes in the combustion chamber and the bulk quenching of the lean mixtures. The key methods for reducing HC emissions in PCCI engines are minimizing crevice volume in the combustion chamber and maximizing intake air temperature allowed based on the permissible NOx level.