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Free-piston heat engines are being examined by a number of international research groups as an option for conservative technology, as they are not limited by the movement of the crankshaft as in conventional engines. The free-piston engines are employed in applications like power generation using conventional methods. The higher compression ratios provide higher cycle efficiencies and also boost in-cylinder temperatures increasing mechanical stress, pressures, and heat transfer losses. This paper presents different in-cylinder flows by computational fluid dynamics for various compression ratios ranges from 7 to 15 and estimates were made to find best compression ratio for the optimal engine operating performance and characteristic.

В результате выполненной работы исследованы особенности выпускной системы поршневых двигателей внутреннего сгорания. Установлены факторы, влияния отработанных газов на окружающую среду. As a result of the work performed, the features of the exhaust system of reciprocating internal combustion engines were studied. Factors, influence of exhaust gases on the environment are established.

The increase of the power density, improvement of fuel efficiency and minimization of the environmental impact of modern internal combustion engines form the main trend of the engine development. Turbocharging is pivotal to ensure the thermodynamical as well as commercial competitiveness of modern large diesel and gas engines. The optimization of the gas-dynamic and heat transfer characteristics of the gas flow in the intake system targeting the optimization of the gas exchange process is an important task in engine building. Numerical simulation of working process of the 8-cylinder 21/21 diesel-motor (Russia, Ekaterinburg) was performed with the ACTUS simulation software (Switzerland, Baden, ABB Turbo Systems Ltd). The numerical study showed that the geometric dimensions of the intake pipe significantly impact the flow dynamics. In particular, it is shown that the use of inlet pipe with a larger diameter (on the 8DM-21 engine) leads to the average 0.5% increase in the filling ratio. This leads to an up to 0.7 % increase in engine power and reduces the effective specific fuel consumption by about 0.50-0.75. © 2017 The Authors. Published by Elsevier Ltd.

Цель работы выявление баланса термодинамической работы в теоретических циклах поршневых компрессоров для решения задачи их оптимального агрегатирования с приводными четырехтактными рядными поршневыми бензиновыми двигателями внутреннего сгорания (ДВС). Для этого необходимо решить следующие задачи: провести моделирование термодинамической работы в теоретических циклах поршневых компрессоров и выявить зависимость термодинамической работы рабочего тела (над рабочим телом) от угла поворота коленчатого вала. В результате обзора научнотехнических источников, разработанных ведущими российскими и мировыми научнотехническими центрами компрессоростроения, выявлено, что теоретическое обоснование параметров поршневых компрессоров осуществляется на основе некоторых средних за цикл термодинамических параметров рабочего тела. Такой подход вполне допустим при проектировании компрессорных установок с приводом от ДВС, включающих маховики для компенсации неравномерности потребления механической энергии в течение рабочего цикла, во время которого происходит постоянное изменение потребляемой поршневым компрессором механической работы. В условиях непостоянства выработки механической работы приводным четырехтактным рядным поршневым бензиновым ДВС это приводит к колебаниям системы вращающихся масс четырехтактный рядный поршневой бензиновый ДВС поршневой компрессор . С целью повышения эффективности функционирования системы четырехтактный рядный поршневой бензиновый ДВС поршневой компрессор необходима синхронизация максимумов выработки механической работы четырехтактным рядным поршневым бензиновым ДВС с максимумом потребления механической работы поршневые компрессором. В первом приближении с целью теоретического обоснования оптимального агрегатирования поршневых компрессоров с приводными четырехтактными рядными поршневыми бензиновыми ДВС выполнено математическое моделирование зависимости термодинамических работ в теоретических циклах четырехтактных рядных поршневых бензиновых ДВС и поршневых компрессоров и определено оптимальное соотношение углов поворота относительно друг друга коленчатых валов приводных четырехтактных рядных поршневым бензиновых ДВС и поршневых компрессоров. На основе полученных результатов выявлены зависимость термодинамической работы рабочего тела в рабочих циклах рядных поршневых компрессоров в функции от угла поворота коленчатого вала зависимость термодинамической работы в рабочем цикле V и Wобразных поршневых компрессоров в функции от угла поворота коленчатого вала закономерности влияния сдвига угла между коленчатым валом ДВС и коленчатым валом компрессора в системах четырехтактный рядный поршневой бензиновый четырехцилиндровый ДВС двухцилиндровый рядный поршневой компрессор , четырехтактный рядный поршневой бензиновый шестицилиндровый ДВС трехцилиндровый рядный поршневой компрессор на пульсации максимальной и минимальной термодинамической работы., The goal of the study is to identify a thermodynamic work balance in theoretical cycles of piston compressors for solving a problem of their optimum aggregation with the driving fourcycle line piston gasoline internal combustion engines (ICE). The objectives of the study are to model thermodynamic work in theoretical cycles of piston compressors and to identify thermodynamic work dependence of a working body (over a working body) on an angle of a bent shaft rotation. The review of the scientific and technical sources of the leading national and international scientific and technological centers of compressor manufacturing has shown that theoretical justification of piston compressor parameters is based on some cycle averages of thermodynamic parameters of a working body. Such approach is quite admissible for the design of compressor installations with the drive from ICE, including flywheels in their structure for compensation of unevenness of mechanical energy consumption during a running cycle when mechanical work consumption by a piston compressor varies. In the conditions of inconstancy of mechanical work generation by a fourcycle line piston gasoline ICE, it causes fluctuations of the rotating mass system of a fourcycle line piston gasoline ICE a piston compressor . In order to increase functional effectiveness of the system of a fourcycle line piston gasoline ICE a piston compressor it is necessary to synchronize maxima of mechanical work generation by a fourcycle line piston gasoline ICE with a maximum of mechanical work consumption by a piston compressor. As a first approximation for the purpose of theoretical justification of optimum aggregation of piston compressors with driving fourcycle line piston gasoline ICEs, we used mathematical modeling of dependence of thermodynamic works in theoretical cycles of fourcycle line piston gasoline ICEs and piston compressors and defined an optimum ratio of angles of rotation of bent shafts of fourcycle power of line piston gasoline ICEs and piston compressors in relation to each other. The main results of the study include the dependence of thermodynamic work of a working body in running cycles of line piston compressors in function on the angle of a bent shaft rotation dependence of thermodynamic work in a running cycle of Vshaped and Wshaped piston compressors in function on the angle of a bent shaft rotation regularities of influence of a corner shift between an ICE bent shaft and a bent shaft of the compressor in the systems of a fourcycle line piston gasoline fourcylinder ICE a twocylinder line piston compressor , a fourcycle line piston gasoline sixcylinder ICE a threecylinder line piston compressor on a pulsation of the maximum and minimum thermodynamic work., №3(11) (2019)

Improving the exploitative and environmental performance of piston engines (PICE) is an urgent task for many engineers and scientists. The article presents the results of the upgrade of a gas-and-air system of a diesel PICE, carried out through changing the turbocharging system's configuration and modernizing the design of the admittance collector. The authors present a review of studies on the given subject and a description of the object of the research. The study was conducted on the basis of bench tests at a manufacturing plant and mathematical modeling using ACTUS program. The results of experimental studies on the main indicators of a basic and upgraded PICEs are presented. The gas exchange processes in the PICE under examination were studied in detail using mathematical modeling. For the given diesel PICE, improvement of the gas-and-air system leads to a growth in charging efficiency by 2.45-3.92%, a decrease in scavenging factor by 3.11-6.31% and a reduction of specific fuel consumption up to 3.33%. In the conclusion, new directions for increasing the efficiency of the given PICE are offered. © The Authors, published by EDP Sciences, 2020. Russian Science Foundation, RSF: 18-79-10003 The work has been supported by the Russian Science Foundation (grant No. 18-79-10003).

Gas-dynamic perfection and intensity of heat exchange of intake systems determine the efficiency of the piston engine. The results of numerical simulation and experimental study of the heat transfer of gas streams in the intake system of engines having different configurations are presented in the article. Methods of modeling, experimental setup, geometric configuration of pipelines and measuring base are described in the paper. The investigations were carried out under steady-state air flow in the system. The results of mathematical modeling were verified using experimental studies. It is established that the use of profiled sections in the intake system leads to a decrease in the heat transfer rate up to 20 % at low air flow rates (up to 40 m/s) and an increase in the heat transfer rate up to 9 % at high speeds. © Published under licence by IOP Publishing Ltd. The work has been supported by the Russian Science Foundation (grant No. 18-79-10003).

This thesis covers general topics concerning the forces, oscillations, manufacturing processes, and design trends of a four stroke internal combustion engine crankshaft and the prior knowledge required to obtain a precise understanding of the crankshaft working conditions and the parameters that affect said conditions. Prior to defining the different forces acting on a crankshaft, basic piston dynamics are explained to establish relations between piston movement and crankshaft rotation since piston and connecting rod masses are a large source of force on the crankshaft. Geometric relations are used to derive kinematic equations that describe piston motion. By considering an ideal Otto cycle and the piston motion equations, a relation between cylinder gas pressure and crankshaft rotation is obtained. These equations are then used to derive the inertial and gas forces acting on the crankshaft. These equations are then used to create a software tool via MATLAB that allows users to input certain engine characteristics and obtain several graphs illustrating torques, piston motion, and gas pressure. The user can change independent parameters to observe how these affect different graphs. Manufacturing processes and their advantages and disadvantages are covered, alongside the different materials, their characteristics, and applications. Finally, the iterative crankshaft design process and key design focus points and their corresponding limitations are covered. Ingeniería Mecánica

In this work, a promising technique, consisting of a liquid Water Injection (WI) at the intake ports, is investigated to overcome over-fueling and delayed combustions typical of downsized boosted engines, operating at high loads. In a first stage, experimental tests are carried out in a spark-ignition twin-cylinder turbocharged engine at a fixed rotational speed and medium-high loads. In particular, a spark timing and a water-to-fuel ratio sweep are both specified, to analyze the WI capability in increasing the knock-limited spark advance. In a second stage, the considered engine is schematized in a 1D framework. The model, developed in the GT-Power(TM) environment, includes user defined procedures for the description of combustion and knock phenomena. Computed results are compared with collected data for all the considered operating conditions, in terms of average performance parameters, in-cylinder pressure cycles, burn rate profiles, and knock propensity, as well. Finally, the validated model is applied to investigate the full potential of water injection in reducing the knock tendency and improving the fuel economy in a wide load range. The numerical results highlight that WI technique involves significant Brake Specific Fuel Consumption (BSFC) advantages, especially at the medium-high loads. These benefits are limited by the maximum allowable levels for the in-cylinder pressure, while additional advantages are obtained in terms of reduced turbine inlet temperature, turbocharger speed, and boost pressure. The developed numerical procedure, based on validated combustion and knock sub-models, is able to take into account the complex interactions among different parameters, which affect the engine behavior. It is hence believed to realistically forecast the WI-related BSFC advantages and constraints, induced by thermo-mechanical stresses. Simultaneously, it underlines the need of a partial engine redesign to fully exploit WI potential.

The improvement of work processes of piston engines to boost the technical and economic parameters is the main objective in the field of power engineering. The improvement of the gas exchange processes (intake and exhaust processes) quality is one of the possible profiles to improve the efficiency and reliability of piston internal combustion engines. The study of the instantaneous local heat transfer at flow unsteadiness is one of the objectives of the experimental studies of the thermomechanical processes in the intake and exhaust systems of the engines. The influence of configuration of the intake and exhaust pipes on the heat transfer intensity is a relevant engineering problem. The local heat transfer intensity data serves as the basis to determine the basis for determination of heating of the air (at intake), cooling exhaust gas (at exhaust), calculation of thermal stresses in the nodes and details of intake and exhaust systems. The article presents the results of the experimental investigation of the instantaneous local heat transfer (taking into account the hydrodynamic nonstationarity) in the intake and exhaust pipes of different configurations for piston internal combustion engines. It is established that the cross profiling of the intake and exhaust pipes of piston engines leads to 5-20% decrease in the local heat transfer intensity depending on the crankshaft speed. © 2017 The Authors. Published by Elsevier Ltd. The reported study was funded by FBR R according to the research project

[EN] The present work includes findings from proof-of-principle feasibility studies on iron nanopowder combustion under idealized, enginelike, and real engine conditions. The study was conducted under the scope of recent interest in metallic nanoparticles as alternative fuels for internal combustion engines. More specifically, Fe nanoparticles with different morphologies and average primary particle sizes ranging from 25 to 85 nm were studied with respect to their oxidation characteristics via thermogravimetric analysis as well as in customized shock tube, constant-volume vessel, and compression-ignition (CI) engine configurations. Combusted powder samples were in all cases examined via in situ and ex situ techniques for the identification of combustion products and their morphologies. The findings facilitated the determination of the main phenomena involved during oxidation. The results verified that combustion of Fe nanoparticles in a slightly modified CI engine is feasible, albeit with various technological challenges related to ignition and scavenging that inhibit combustion quality., The authors thank the European Commission for partial funding of this work through the Project “COMETNANO” (FP7-NMP4-SL-2009-229063).

In–cylinder pressure trace analysis is an important investigation tool frequently employed in the study of internal combustion engines. While technical data is usually available for experimental engines, in some cases measurements are performed on automotive engines for which only the most basic geometry features are available. Therefore, several authors aimed to determine the cylinder volume and length of the connecting rod by other methods than direct measurement. This study performs an evaluation of two such methods. The most appropriate way was found to be the estimation of connecting rod length based on general engine category as opposed to the use of an equation that predicts cylinder volume with good accuracy around top dead centre for most geometries.

[EN] In-cylinder pressure signal has been largely used for analysing the combustion in reciprocating engines, mainly in test benches, although new engines are being designed with closed loop control based on the in-cylinder pressure feedback. Normally the pressure signal is filtered for removing the high frequency components and implement pressure applications based on the low-frequency components (, [ES] La señal de presión en cámara en Motores de Combustión Interna Alternativos (MCIA) ha sido empleada comúnmente para el diagnóstico de la combustión en bancos de ensayo. Normalmente, la señal de presión es filtrada para eliminar las componentes de alta frecuencia y poder implementar distintas herramientas basadas en las componentes de baja frecuencia de la señal de presión (

In this article, Large Eddy Simulations (LES) of Spark Ignition (SI) engines are performed to evaluate the impact of the numerical set-upon the predictedflow motion and combustion process. Due to the high complexity and computational cost of such simulations, the classical set-up commonly includes “low” order numerical schemes (typically first or second-order accurate in time and space) as well as simple turbulence models (such as the well known constant coefficient Smagorinsky model (Smagorinsky J. (1963) Mon. Weather Rev. 91, 99-164). The scope of this paper is to evaluate the feasibility and the potential benefits of using high precision methods for engine simulations, relying on higher order numerical methods and state-of-the-art Sub-Grid-Scale (SGS) models. For this purpose, two high order convection schemes from the Two-step Taylor Galerkin (TTG) family (Colin and Rudgyard (2000) J. Comput. Phys. 162, 338-371) and several SGS turbulence models, namely Dynamic Smagorinsky (Germano et al. (1991) Phys. Fluids 3, 1760-1765) and sigma (Baya Toda et al. (2010) Proc. Summer Program 2010, Stanford, Center for Turbulence Research, NASA Ames/Stanford Univ., pp. 193-202) are considered to improve the accuracy of the classically used Lax-Wendroff (LW) (Lax and Wendroff (1964) Commun. Pure Appl. Math. 17, 381-398) - Smagorinsky set-up. This evaluation is performed considering two different engine configurations from IFP Energies nouvelles. The first one is the naturally aspirated four-valve spark-ignited F7P engine which benefits from an exhaustive experimental and numerical characterization. The second one, called Ecosural, is a highly supercharged spark-ignited engine. Unique realizations of engine cycles have been simulated for each set-up starting from the same initial conditions and the comparison is made with experimental and previous numerical results for the F7P configuration. For the Ecosural engine, experimental results are not available yet and only qualitative comparisons are performed to enforce the analysis and conclusions made on the F7P configuration. Regarding SGS models, only slight differences are found at the aerodynamic level even if sigma allows a better resolution of small structures of the velocity field. However, all results are in cycle-to-cycle variability envelopes from Granet (Granet et al. (2012) Combust. Flame 159, 1562-1575) and these single cycle computations don’t permit to distinguish clear improvements on macroscopic parameters such as resolved kinetic energy, heat release or mean in-cylinder pressure. Concerning numerical schemes, TTG schemes also allow a slighlty better resolution of small scale vortices but global quantities such as resolved kinetic energy and SGS viscosity are comparable. Nevertheless, clear differences appear between the different schemes in the combustion stroke. This is attributed to a better resolution of the flame-turbulence interaction process during the free flame propagation period, leading to an increase of the resolved part of heat release. It is also shown in this paper that an adjustment of the efficiency constant in the Thickened Flame (TF) model is compulsory to account for the over dissipation of the smallest resolved structures if LW is used. In the light of these conclusions an hybrid setup, called ES O2 (Engine Stroke Optimal Order), which consists in using TTGC during combustion and LW elsewhere is proposed and applied to the two engines configurations. Results are in good agreement with the ones obtained in the case of a full TTGC simulation, while the CPU (Central Processing Unit) cost increase is only about 10% compared to LW. The accuracy of LW seems therefore to be sufficient for pure aerodynamic phases, while the use of TTGC only during combustion permits an improvement in the LES quality. The hybrid ES O2 method thus appears as an attractive approach to improve further calculations accuracy without being greatly penalized by additional CPU costs in multi-cycle simulations.

In this study, by preparing a dynamic model for the system consisting of piston, piston rod, crankshaft and block of a single cylinder four stroke diesel engine, the speed fluctuations of the crankshaft and translational vibrations of the engine block were examined. The dynamic model has four degrees of freedom as; the angular motion of the crankshaft, the angular motion of the engine block around the crankshaft center, and the translational vibrations of the engine block in the vertical and horizontal directions. In the analysis, the pressure profiles obtained from a single cylinder four stroke diesel engine at four different engine loads were used. The oscillation of crankshaft angular velocity was found to be increasing with the engine load. The angular vibrations of the engine block around the crankshaft center was found to be arising from the gas forces, the translational vibrations in the vertical and horizontal directions were found to be arising from the inertia of piston and unbalance of crankshaft. It was found that the counterweight used for minimizing the vertical vibration generates a horizontal vibration besides reducing vertical vibration. Therefore, reduction of its amplitude into the half was found to be more appropriate, instead of reducing to zero. From the mount force datum, which is dependent on frequency, the optimum spring and damping constants of the mounts were found as 100 kN/m and 1000 Ns/m, respectively.

It is known that more than 80% of global energy is produced by internal combustion engines. Therefore, the improvement of working cycles and modernization of systems and components of the piston and combined internal combustion engines with the aim of improving their technical and economic indicators is one of the urgent tasks in the global energy sector. Research studies in this area were carried out mainly by means of numerical simulations or experimentally under static conditions. Information about gas exchange processes in the unsteady gas dynamic conditions are quite limited and controversial. This work aims at obtaining of the additional clarifying information about the gas dynamics in the air-gas tract of the internal combustion engine and finding ways of improving the processes. The results of experimental studies of gas exchange processes in the intake and exhaust tracts piston engines were presented in the article. Experimental studies were conducted on full-scale models of a single-cylinder engine. The experimental dependencies of change of the instantaneous velocity and pressure of the gas flow in the gas paths from the crank angle were presented in the article. Improvement of gas exchange processes in the intake and exhaust pipes of internal combustion engines due to the transverse profiling of the channels was proposed in the paper. © 2016 The Authors.