CFD Analysis of a Large Marine Engine Scavenging Process

The scavenging process is an important part of the two-stroke engine operation. Its efficiency affects the global engine performance such as power, fuel consumption, and pollutant emissions. Slow speed marine diesel engines are uniflow scavenged, which implies inlet scavenging ports on the bottom of the liner and an exhaust valve on the top of the cylinder. A CFD model of such an engine process was developed with the OpenFOAM software tools. A 12-degree sector of the mesh was used corresponding to one of the 30 scavenging ports. A mesh sensitivity test was performed, and the cylinder pressure was compared to experimental data for the analyzed part of the process. The scavenging performances were analyzed for real operation parameters. The influence of the scavenge air pressure and inlet ports geometric orientation was analyzed. The scavenging process is analyzed by means of a passive scalar representing fresh air in the cylinder. Isosurfaces that show the concentration of fresh air were presented. The variation of oxygen and carbon dioxide with time and the axial and angular momentum in the cylinder were calculated. Finally, the scavenging performance for the various operation parameters was evaluated by means of scavenging efficiency, charging efficiency, trapping efficiency, and delivery ratio. It was found that the scavenging efficiency decreases with the engine load due to the shorter time for the process. The scavenging efficiency increases with the pressure difference between the exhaust and scavenging port, and the scavenging efficiency decreases with the increase in the angle of the scavenging ports. It was concluded that smaller angles than the industry standard of 20° could be beneficial to the scavenging efficiency. In the investigation, the charging efficiency ranged from 0.91 to over 0.99, the trapping efficiency ranged from 0.54 to 0.83, the charging efficiency ranged from 0.78 to 0.92, and the delivery ratio ranged from 1.21 to 2.03.

The study of a tractor diesel engine operation on ethanol and rapeseed oil at various speed modes

Introduction (problem statement and relevance). The depletion of oil fuels reserves and the steady growth of their consumption will require new solutions in the development of technologies based on renewable energy sources. The study of the possible alternative fuels use in internal combustion engines is a complex scientific task, including the research of the alternative fuels effect on the power plants operation efficiency.The purpose of the study was to obtain the speed characteristics of a diesel engine operating on ethyl alcohol and rapeseed oil.Methodology and research methods. An air-cooled with volumetric mixture formation tractor diesel engine of dimension 2Ch 10.5/12.0 was selected as an object of research. The study was carried out by a comparative method. To measure the speed characteristic a fixed cyclic fuel supply was applied after the engine reaching the nominal operating mode at a crankshaft speed of 1800 min-1 and an average effective pressure in the cylinder of 0.588 MPa. This approach, with the all-mode regulator of the fuel pump turned off, made it possible to identify the main regularities of intra-cylinder processes at different speed modes of engine operation.Scientific novelty and results. The article presents the bench tests results of a diesel engine operating at various speed modes on ethanol and rapeseed oil, and analyzes in detail the main indicators of the combustion process and the effective engine performance in comparison to the use of traditional fuel. The practical significance lies in the possibility of using the obtained results to improve the diesel engines operation on alternative renewable fuels.

Boosting engine performance with Bose-Einstein condensation

At low-temperatures a gas of bosons will undergo a phase transition into a quantum state of matter known as a Bose-Einstein condensate (BEC), in which a large fraction of the particles will occupy the ground state simultaneously. Here we explore the performance of an endoreversible Otto cycle operating with a harmonically confined Bose gas as the working medium. We analyze the engine operation in three regimes, with the working medium in the BEC phase, in the gas phase, and driven across the BEC transition during each cycle. We find that the unique properties of the BEC phase allow for enhanced engine performance, including increased power output and higher efficiency at maximum power.

ДОСЛІДЖЕННЯ РОБОТИ СИСТЕМ КЕРУВАННЯ ДОЗУВАЛЬНИМ ОБЛАДНАННЯМ БЕЗПЕРЕРВНОЇ ДІЇ З «ПІ» ТА «ПІД» РЕГУЛЯТОРАМИ

Purpose. Investigation of transients in the control system of continuous dosing equipment for bulk materials using PI and PID regulators and evaluation of their impact on the quality of work elements.Method. Using the Mathlab: Simulink software environment to develop a mathematical model, conduct experimental research and assess the impact on the working bodies of the control system of continuous dosing equipment.Researchresults. Control of motor parameters (motor characteristics) by means of standard regulators of their comparison of advantages and disadvantages. described in many standards and scientific papers. However, modeling the engine operation process in dosing systems is significantly complicated due to the inertness and adhesion of bulk material dosed in the core of the hopper, it can significantly affect the final result of the finished mixture. continuous operation equipment using PI and PID controllers, an experiment was performed on a mathematical model using PI and PID controllers to assess their impact on the control system of the plate feeder continuous action. The results of the simulation can be used to decide on the type of controller control of transient characteristics of the engine, at development of control system of plate feeders in mixing complexes of continuous action.Scientificnovelty. Scientific novelty. The parameters influencing the frequency with which the motor of the plate feeder of continuous action rotates are determined. The time of the transient process of engine operation and the value of the maximum dynamic deviation are determined. The expediency of using regulators of one or another type for certain modes of operation of feeders is proved.Practical significance. The obtained results will reduce the transient time in the operation of the feeder motor and increase the operating time until the failure of the entire system. Design changes are proposed that will reduce the amount of ripple and improve the performance of continuous dosing equipment.

Fouling Mitigation for Laser Igniters in Natural Gas Engines

Due to several recent developments in lasers and optics, laser igniters can now be designed to be (i) compact so as to have the same footprint as a standard spark plug, (ii) have low power draw, usually less than 50 Watts, and (iii) have vibration and temperature resistance at levels typical of reciprocating engines. Primary advantages of these laser igniters remain (i) extension of lean or dilution limits for ignition of combustible mixtures, and (ii) improved ignition at higher pressures. Recently, tests performed in a 350 kW 6-cylinder stationary natural gas reciprocating engine retrofitted with these igniters showed an extension of the operational envelope to yield efficiency improvements of the order of 2.6% points while being compliant with the mandated emission regulations. Even though laser igniters offer promise, fouling of the final optical element that introduces the laser into the combustion chamber is of concern. After performing a thorough literature search, a test plan was devised to evaluate various fouling mitigation strategies. The final approach that was used is a combination of three strategies and helped sustain an optical transmissivity exceeding 98% even after 1500 hrs. of continuous engine operation at 2400 rpm. Based on the observed trend in transmissivity, it now appears that laser igniters can last up to 6000 hrs. of continuous engine operation in a stationary engine running at 1800 rpm.

Design and Simulation of Air-Fuel Percentage Sensors in Drone Engine Controlling

This paper presents the design and simulation of air-fuel percentage sensors in drone engine control using Matlab. The applications of sensor engineering system have been pioneer in technology development and advancement of automated machine as complex systems. The integration of drone fuel sensor system is the major series components such as injector, pumps and switches. The suggested model is tuned to interface drone fuel system with fuel flow in order to optimize efficient monitoring. The sensor system is improved and virtualized in Simulink block set by varying the parameters with high range to observe the fuel utilization curves and extract the validated results. The obtained results show that the possibility of engine operation in critical conditions such as takeoff, landing, sharp maneuver and performance is applicable to turn off the system in case of break down in the sensor to ensure the safety of drone engine. HIGHLIGHTS The drone engine fuel rate sensor is designed and examined to determine the air-to-fuel ratio The suggested model is tuned to interface drone fuel system with fuel flow in order to optimize efficient monitoring The obtained results show that the possibility of using engine with different failure mode and fault considerations The represented control structure is simple, efficient and provides the required air-to-fuel ratio

The effect of using different Biodiesel fuels on jet development in a Diesel engine

The fuel properties and the injection rate-shape play an important role in the improvement of the combustion process of Diesel engines. In this work, the influences of using the forthcoming renewable biodiesel fuels on fuel jet development utilizing a computer simulation model created with the AVL Hydsim software were studied. Biodiesel fuels B20, B30 and B100 were considered and compared with the original pure Diesel fuel D100. The injection system behaviour under research was that one existing on a tractor engine equipped with Delphi DP200 pump and Delphi injectors. Two engine speeds of 1400 rpm and 2400 rpm were considered representative for the engine operation. For these speeds, the fuel jet characteristics as penetration, spray cone angle and Sauter mean diameter were analyzed. It can emphasize that in similar conditions of needle lift and injection rate-shape variation the usage of biodiesel fuels does not significantly alter the injection pressure and the Sauter mean diameter. However, the specific physical properties of biodiesel fuels affect substantially the spray penetration and its cone angle.

Methods for estimating the durability of the needle bearing of the piston head of the connecting rod of a transportation diesel

The article presents the results of an experimental study and analytical evaluation calculations to check service life and increase durability of the needle bearing of piston head of connecting rod of a transport diesel engine. The primary reasons for the violation of the nominal operation of the main units of this mechanism have been established. Corresponding recommendations are proposed for carrying out accelerated tests for durability, reducing the thermal loads of the bearing operation and, as a consequence, improving the quality and service life of its entire piston group. Theoretical and experimental methods for determining the nominal life of the needle bearing of the piston head of the connecting rod (PHCR) of a transport diesel engine are proposed. The theoretical methodology allows obtaining reliable values of durability, taking into account the distribution of the working load over the rolling elements, as well as the mobility of the piston pin and sleeve. The performed calculations make it possible to correct and clarify the standard mathematical model for determining the nominal life of the PHCR needle bearing, depending on the distribution of loads on the rolling elements (rollers) under different operating conditions. This experimental technique with an acceleration factor of 10 is based on a twofold increase in the force effect on the elements of the PHCR needle bearing. This was achieved by assembling the bearing using a special technology, which is described in detail in the work. A significant decrease in the thermal effect and a decrease in radial loads on working rollers have been established. For ensure the regular oil supply into bearing during engine operation, a technique was developed to increase the load on the roller in contact zone, which significantly influenced durability and made it possible to conduct accelerated tests with a reliable yield. Its results of operational research and experience in design work correlate and are sufficiently explained by the developed methods, which allows them to be used for the improvement and modernization of connecting rods with needle bearings in PHCR. That is a permission to use these methodic for doing perfect and modern the needle bearing of the connecting-rod piston. Keywords: diesel, test procedure, needle bearing, rollers, piston head of the connecting rod, durability.