Permissible Pressure Research Articles

Definition of Contact Stresses and Gaps in the Hinges of Chain Gears

The article discusses the issues of determining contact stresses in the hinges of chain gears. It is necessary to know these stresses to assess the hinges’ wear resistance, since the wear of hinges (joints) is the most common cause of chain gears’ damage. In this regard, the focus was made on determining the necessary gap between the bushing and the roller of the chain gears. This gap significantly affects the largely determines the distribution pattern and magnitude of the stresses in the hinge, and, consequently, the wear resistance of chain gears. A method for calculating the maximum contact stress in the hinges of chain gears has been developed. It was proved that a decrease of the gap in the hinges influence in the following way: the contact angle between the roller and the bushing increases and the maximum contact stresses become lower. However, for real contact angles, the contact stresses greatly exceed the permissible average specific pressure, causing increased wear on the joints (hinges). One of the possible ways to solve this problem is to use transitional fittings in hinges, in which the gaps and tightness are relatively small. When pressing the rollers into the bushings, microroughnesses are cut from the contact surfaces, and the tightness in the connection practically disappears. Some examples of determining gaps and contact stresses in the hinges of chain gears are given.

D.L. KATZ METHOD IN OILFIELD PROBLEMS SOLUTION

Background The separation of gas from oil occurs throughout the entire technological process of oil production and preparation due to the constant or periodic decrease in pressure in oilfield equipment. Only in borehole conditions, gas release from oil is observed twice: before and after the downhole pump. In surface conditions, an efficient multistage separation of gas from oil ensures economical and safe transportation of oil through the pipeline system, stabilization of oil and obtaining the maximal amount of marketable oil. The last two tasks are directly related to the permissible saturated vapor pressure of the oil and its component composition when delivering commercial oil to the consumer. The article discusses the solution of several tasks for the preparation of borehole products using the D.L. Katz method. Aims and Objectives o to determine the optimal position of PP-4V track heater in the technological chain of the water discharge and oil preparation unit; o to evaluate the possibility of using the D.L. Katz method for rapid assessment of saturated gas pressure of reservoir oil. Methods To calculate the component composition of the gas phase and the separated oil, the material balance method was used, which is expressed in the equality of moles of a certain component of the system before and after phase separation. Results According to D.L. Katz method there calculated 5 types for the degassing of reservoir oil from the Yarakta oil and gas condensate field. Among the considered three types for three-stage separation, the optimal position of the PP-4V track heater in the technological sequence of oil preparation was determined. Based on the analysis of the calculations, the possibilities of using the method of material balance and contact separation of gas from oil at various pressures in the PVT chamber to determine the pressure of saturation of oil with gas are substantiated.

Research of long-term stability of the near-wellbore zone

The authors used the criterion of short-term rock strength, transformed for the case of long-term strength in order to assess the long-term stability of the borehole wall and determine the permissible pressure in the wellbore. The long-term strength criterion is written according to the method of P.P. Balandina. As a result of the study, it was proved that the determination of the long-term strength of a rock is reduced to a decrease in the values of the short-term strength limits. A curve of the long-term strength of an inclined well is constructed according to a generalized dependence. The expression is obtained that allows determining the time of long-term strength.

Permissible ground pressure of wheeled forestry vehicles depending on the ground conditions

The aim of the work is to investigate interrelations between wheeled vehicle pressure on the ground and its cross-country ability. To comply with the requirement of ecological compatibility of the mover, which is that the rut depth after the passage of the vehicle should be less than 0.1 m, the pressure of the wheeled mover when working on moderate forest soils should not exceed 0.07 MPa (a forwarder 8x8 with a loaded weight up to 31 tons), on weak forest soils the pressure should not exceed 0.025 MPa (a forwarder 8x8 with a loaded weight up to 11 tons). On moderate soil to ensure cross-country ability, the pressure should be limited to 0.095 MPa (a forwarder 8x8 with a loaded weight up to 42 tons) (slipping ratio reaches 0.2, the depth of the rut is 0.18 m, the operating speed of the machine 1.5 m/s). To ensure the wheeled vehicle cross-country ability, the average pressure when working on weak forest soils should be limited to 0.04 MPa (a forwarder 8x8 with its loaded weight of up to 18 tons) (slipping coefficient reaches 0.136, rut depth of 0.253 m, the operating speed of the machine 2.8 m/s).

Substantiation of connection of diagnostic indicators with parameters of technical condition of hydraulic manipulators

At the organization of proactive system of maintenance of mechanisms the technique based on determination of relative probability is applied. But in contrast to the technique, when the machine is for maintenance and adjusted the type and frequency of the hydraulic manipulators (HM) it is necessary to carry out constant monitoring of the technical condition of the main elements of the mechanism. The main elements of the HM, which primarily determine its technical condition, are the distribution system, including the pump, oil pressure distributors in the executive bodies of the HM, as well as the column, the extension-grip joint and the rotator. Nominal and permissible pressure values in the distribution system are determined by the technical documentation on the HM. The paper considers the dependence of the vibration signal on the technical condition of the coupling shaft-gear column HM.

Innvative Basic Robotechnical Mechanism for Implementation of Precisional Agriculture

In agriculture, the soil acts as a physical and biological environment that provides cultivated plants with life factors (water-air, food regimes, etc.), at the same time, the soil becomes the bearing surface for tillage agricultural machines. The increase in the productivity of agricultural energy causes the growth of their mass and the pressure on the soil of the running systems. Thus, in recent years, the mass of tractors per unit area of arable land has increased 3 times.Modern machine-tractor units are when growing crops passed through the field 5-15 times, which leads to the compaction of arable and subsurface of soil layers. In General, the running systems of machines are cover up to 80% of the field area, and on row crops (potatoes, sugar beet, etc.). The fields are exposed to 3-5 times the impact of units. The total area of their traces in the performance of the whole complex of field work is 100-200% of the field area. [1]For most soils, the permissible specific pressure is 0.4-0.5 kg/cm2 and the maximum is 1.0-1.5 kg/cm2. However, energy-saturated wheeled tractors put pressure on the soil up to 3-4 kg/cm2 or more.Soil compaction worsens its agrophysical properties, suppresses the activity of soil biota, causes poor-quality seeding and reduction of their field germination, reduces the moisture content of plants, as well as accelerates erosion processes.Ultimately, all this leads to lower yields. In studies Matuzova G. V. and etc. [2] with an increase in the volume weight of the soil from the tractor engines from 1.05 to 1.49 g/cm3, the yield of green mass of Vico-oat mixture decreased from 218.3 to 116 C/ha almost 2 times.The most important technical measures to reduce the compacting effect of agricultural machines on the soil include: the development of soil conservation systems of tractors (new types of caterpillar and pneumatic engines, elastic – ultra-low pressure tire) and agricultural machinery, non-tractor machines system (bridge, rope farming) and other constructive solutions.Considered in the bridge system in the form of a self-moving platform is designed to perform in an automated mode a set of technological operations in the cultivation of crops, while providing a slight negative impact on the soil cover. The bridge technical complex is a platform approximately 10 x 30 m made of profiles. In short 10 - meter hollow profiles is moved by using a ratchet mechanism and 30-meter profile, which is equipped with roller bearings rail-beam, providing step-by-step movement of the platform on rigid supports in the form of concrete blocks and placed on gravel-pebble pillows every 10 meters each or gravel-pebble drainage on reclamation systems. An automated technological module is mounted on 30-meter cross beams, which is moving along the long beams in an automated mode, performs the specified operations and according to these operations the platform is moved along the rail beams to the next cells. After reaching the edge of the rail-beams of the platform with the help of hydraulic cylinders, resting on a reinforced concrete beam-supports (or drainage system) is lifted, freeing the rail-beams, which with the help of ratchet mechanisms are moved to the next position. Subsequently, the hydraulic cylinders are supporting the platform in a balanced position to relax, the platform rests on the rail-beams, and the technological operation is repeated.The bridge platform having a rigid base and an electronically-oriented system for adjusting the position of the technological module ensures the accuracy of the technological operations brought to each specific plant, the location of plant is recorded in the computer memory, as well as the application of the specified program at the level of small areas or individual plants of the norms of life support (moisture, fertilizers, chemical protection means, etc.).Having a rigid support of movement positively solved the problems of reducing energy consumption for the module operation, moving the platform, reducing dependence on weather conditions, the state of the soil cover and human costs, etc. The bridge system in the proposed version can solves the problems of efficiency, aesthetics and attractiveness of agriculture as a production.

Computational and experimental assessment of the influence of ultra-low pressure tires of mobile power equipment on soil

The article describes a method for determining the maximum pressures in contact of an ultra-low pressure tire with deformable soil: with low bearing capacity using the example of a thin-walled tire 1020x420-18 of the Bel-79 model. In the current practice of determining the effect of pneumatic tires on the soil, the method of determining the contact area of a tire on an undeformable flat bearing surface is used. By dividing the load on the tire by the obtained contact area, multiplied by correction factors, the maximum tire pressure on the soil is obtained. By comparing the maximum pressure obtained in the tire contact with the non-deformable bearing surface with the permissible pressure, the correspondence of tractor and agricultural tires to operating conditions on soils with a certain moisture and hardness is evaluated. But this method of assessment is unacceptable for tires of low and ultra-low pressure due to significant deformation of the tire and soil: in contact and, therefore, a larger contact area and lower values of maximum and average pressure on the soil. Therefore, the novelty of the work is an experimental assessment of the impact on the soil of tires of low and ultra-low pressure on deformable soil. The method includes the experimental determination of the dependence of tire and ground deformations on air pressure in a tire and load, as well as the dependence of the contact area sizes on deformable soil on tire and ground deformations. The contact areas and the coefficients of the uneven distribution of pressure in the contact according to the average values and shapes of the diagrams determine the maximum pressure in the contact of the tire with deformable soil. As a result, the curves of the dependences of maximum pressures in contact on air pressures and loads on deformable soil for low and ultra-low pressure tires were obtained for the first time. The dependences of maximum pressures in contact on air pressure at fixed loads can be a kind of passport for thin-walled tires, similar to the traction characteristics of tractor tires and the traction and speed characteristics of automobile tires. The results obtained make it possible to determine with high accuracy the operating conditions of high-traffic vehicles on low and ultra-low pressure tires.

DIESEL ENGINES DIAGNOSIS AND IMPROVEMENT OF REPAIR AND OPERATION

Introduction. In the practice of operating and repairing locomotive diesel engines there are cases when a diesel engine is put into operation after repair works with a set of defects of the high-pressure fuel equipment, the cylinder-piston group and the valve timing gear, and rather large uneven distribution of power over the cylinders which has not been fully remedied. It is known that during operation, especially in conditions of frequent load changes, the number of operational defects increases. Hard-to-detect defects in the fuel equipment, the cylinder-piston group and the valve timing gear lead to an uneven distribution of power over the cylinders, an increase in the overall level vibration, a significant increase in specific fuel consumption and an even greater soot emission and hazardous substances during transient conditions. Moreover, routine maintenance work does not always eliminate all defects on the engine, because, firstly, there is no detailed picture of the defects of the individual components before the repairs and, secondly, there is no parametric testing of the condition of the high-pressure fuel equipment, the cylinder-piston group and the valve timing gear after repair work. Purpose. The task of the effective and reliable diagnostics of the technical condition of the engine components before carrying out repair work to accurately detail the scope of the upcoming repair is crucial as well as the subsequent quality control of the repairs, as a result of which the remaining unresolved defects can be identified. After eliminating defects, it is necessary to evenly distribute the load between the cylinders, which should done by balancing the mean indicated pressure Pi (MIP) with the permissible pressure deviations Pz at the end of compression Pc and exhaust gas temperatures Texh. Results. The research of the working process undertaken by the staff of the Department of Ship Power Plants and Technical Maintenance of Odessa National Maritime University showed that during rheostat tests of K6S310DR diesel engines it is possible to promptly obtain reliable diagnostic information. This is done by using parallel analysis of the pressure-volume diagrams and vibration records of the high-pressure fuel equipment, the cylinder-piston group and the valve timing gear. The spectral analysis of vibroacoustic signals of the gas turbocharger and the analytical method for eliminating the effect of power leakage in the discrete spectrum allows for on-line diagnostics of the oscillation level of the gas turbocharger rotor. Conclusions. These methods, implemented in the DEPAS system developed by the specialists of Odessa National Maritime University, can be effectively used in practice of operating locomotive diesel engines.

ENVIROMENTAL ASPECTS OF NOISE ASSESSMENT AND REGULATION IN THE DESIGN OF PORT COMPLEXES IN RUSSIA

A comparative analysis of various biological objects sensitivity to acoustic effects is being conducted. For many animal species, the frequency range at which sounds are heard is very different from that for humans and may not even intersect with it. The total frequency range at which various animals can hear covers at least eight orders of magnitude (from hundredths of Hz to hundreds of kHz), while for humans this interval is limited to only four orders of magnitude. Thus, the existing anthropocentric standards for permissible noise levels are unsuitable for regulating their impacts on natural ecosystems and it is necessary to develop standards for sound pressure levels in the entire specified frequency range that are acceptable for the most sensitive recipients. For terrestrial and riparian ecosystems and protected areas, natural test subjects are birds, for which noise levels of 35-40 dBA do not cause pathological changes in behavior and physiological processes. This level can tentatively be considered as maximum permissible for man-made noise and for the noise of ports in particular. More reliable results will be given by regulating the permissible sound pressure levels in the entire frequency range based on reactions of the most sensitive recipients in each octave.

Modelling the stress-strain state of tubular springs in the ANSYS software package

The paper presents the results of calculating the stresses and strains of manometric tubular springs under loading by internal pressure and external force. For research, the finite element method implemented in the ANSYS program was used. The problems of constructing a grid model of the tubular element were solved, the displacements of the free end and stresses from internal pressure were determined, and the maximum permissible pressure value was found.

Optimum design of cryogenic pump for circulation cooling of high temperature superconducting cables

Pressure drops and temperature rises caused by the cooling with liquid nitrogen are evaluated for two typical examples of HTS cables. One is the three-in-one-type AC cable located inside a corrugated pipe, and the other is the single-core-type DC cable located inside a straight pipe. The theoretical expressions of pressure drop and temperature rise indicate the contributions from three components such as the friction between the liquid nitrogen and the wetted surfaces, the ratio of the heat input to the mass flow rate of liquid nitrogen and the vertical change of position along the cooling pipe. The numerically estimated results are validated by comparing them with the test results carried out by the other groups. Furthermore, the maximum feeding distance of HTS cable can be determined by adjusting the flow rate of pump if the maximum permissible pressure drop and temperature rise are fixed in advance.

Using of the methods of landscape research in determining allowable recreational pressure

The development of tourism, as one of the most dynamically developing sectors of the economy, entails an increase in the recreational pressure on the visited territories. The research of modern landscapes shows that their use for recreational purposes can lead not only to significant negative changes in individual components, but also to fundamental disturbances and degradation of landscapes in general. In this connection, the systematic monitoring of the recreational pressure, the search for its optimal values, which do not entail the degradation of the landscape, is of particular relevance. Research of the recreational capacity of landscapes was started as far back as the twentieth century. Over the past decades, the standards of recreational pressure for the most common types of landscapes have been defined. Based on the developed methods of assessing the degree of recreational landscape digression, measures to improve the landscape have been proposed. It has been established that the increase in the economic effect from the development of tourism and recreation is possible on the basis of landscape and recreational analysis, which takes into account the individual characteristics of the territory when determining the permissible recreational pressure. The article briefly describes the main groups of landscape research methods used in determining the permissible recreational pressure on the landscape. The most important parameter on which the researchers rely when they calculate the permissible recreational pressure on the landscape is the density of the recreational pressure. During research of the density of recreational pressure, some traditional methods of researching landscapes are applicable, for example, conducting reconnaissance routes. The analysis of approaches to the definition of permissible recreational pressure on the landscape is spent, a brief algorithm for conducting landscape research at the local level is given, and the example of creating the appropriate landscape maps is given. The article presents the results of landscape researches, conducted on the territory of the Vorotynsky district of the Nizhny Novgorod region. The analysis shows that sustainable development of tourism and recreation can be based on the results of extensive research, including the establishment of landscape features of the territory and the determination of optimal types of recreational activities and the degree of its intensity for each natural-territorial complex.

KINEMATIC SYNTHESIS OF CRANK-SLIDER MECHANISM OF THE GRIPPING DEVICE BASED ON THE POWER TRANSMISSION INDEX

Purpose. The main purpose of the work is to carry out a kinematic synthesis of a crank-slider gripping device in accordance to the criterion of the constancy of the drive power of the mechanism with restrictions on permissible pressure angles in kinematic pairs. Methodology. Achieving this purpose is carried out by means of the theory of mechanisms and machines using the analytical method of the Ozols triangles of kinematics of plane rod mechanisms and mathematical modeling of the movement of links. Findings. The ten-bar mechanism of the gripping device is built on the basis of a paired parallelogram of a crank-slider mechanism with a leading slider. For gripping device, which is built on the basis of the rod scheme, it is advisable optimal design using the criteria for the transfer of motion or transmission indices. The criterion of optimization is the ratio of the speed of the leading link to the projection of the velocity vector of the driven point on the direction of the clamping force vector (power transmission index). The lowest energy costs can be achieved, provided that this ratio is equal to one. Analytical dependences are obtained for determining the velocity function of the central and de-axial crank-slider gripping device, which are convenient for analysis and modeling. On their basis, an energy synthesis of the geometrical parameters of the mechanism of the gripping device in accordance with the criterion of the smallest deviation from the unit ofpower transmission index is performed. The possibilities of the gripping device are enhanced by using it in a de-axial crank-slider mechanism, and the best results can be obtained in a scheme where the de-axial value is larger than the crank length. It is determined the specific values of the relative parameters of the lengths of the links and the ranges of rotation of the crank of the central and de-axial crank-slider of the grippingdevice, which best meet the optimization criterion and satisfy the pressure angle constraints. Originality. For the first time, a new criterion for the transmission of motion was introduced –power transmission index. According to this criteria, a kinematic synthesis of the gripping device built on the basis of a paired crank slider mechanism was carried out. Practical value. Practical recommendations are proposed on the size and location of the links of the mechanism for the central and de-axial crank-slider mechanism, which satisfy the requirements of the optimization criterion and implement restrictions on permissible pressure angles.

TECHNOLOGY OF THE MAINTENANCE OF ACOUSTIC COMFORT ON THE TRANSCAUCASIAN HIGHWAY IN THE ZONE OF THE RESIDENTIAL AREAS ADJUSTING THE MOTOR ROAD

The article presents the results of scientific research on the assessment of the acoustic characteristics of the interstate highway of the Central Caucasus, passing through the mountainous territory of the Republic of North Ossetia Alania in the residential area where the miners of the Sadon Lead-Zinc Plant live. A schematic diagram of the highway in the zone is shown, and a design diagram is given to determine the acoustic parameters of the impact of traffic noise on the habitat of the resident population. On the basis of the studies performed, the most effective design parameters of the acoustic shield are set, providing sanitary permissible sound pressure levels in apartments without additional sound insulation and in the zone of influence of roadside noise in the settlement at the maximum intensity of the traffic flow along the road. Recommendations on the effective operation of the acoustic shield and the method for estimating the noise factor in the mountain zone with a highly dissected relief are given.

GENERATION REGULARITIES OF VIBRATION AND NOISE SPECTRA OF THE GEARBOXES OF OVERHEAD TRAVELING CRANES

The acoustic system of the overhead traveling cranes includes the following diverse sources of acoustical radiation: rails, wheel sets, a base frame, gears and motors of the lifting and moving mechanisms. The acoustic characteristics of the motors do not exceed the maximum permissible sound pressure levels. The gearboxes as the sources of noise and vibration are the most complicated units; moreover, they arrive at the manufacturing factories already being assembled. Therefore, when assessing the sound pressure levels of the cranes in whole, it is advisable to use the experimental data of the noise and gearbox vibration spectra.

Different Failure Mechanisms in Keyed Shaft-Hub Connections under Dynamic Torque Load

Keyed shaft-hub connections are a very popular way to transmit torque via form fit in drive technology. Still in use for decades, they seem to be well known and current in design, although multiple field failures show existing gaps and uncertainties in the design. For this reason, numerous keyed shaft-hub connections were experimentally investigated and analyzed for their failure due to torsional loading.Keyed shaft-hub connections can be designed due to two different criteria: On the one hand, there is the maximum permissible contact pressure in the keyways that, if exceeded, causes a failure via an unacceptable plastic deformation of the keyway. On the other hand, there is the fatigue strength of the shaft or more specifically the connection. The results are based on a large amount of experiments of keyed shaft-hub connections under dynamic torque load. The experimental results of the investigations were analyzed with regard to different failure mechanisms and their dependencies. Most of the investigations focused on the failure caused by inadmissibly high plastic deformation of the shaft keyway. Furthermore, the transition from an unacceptable plastic keyway deformation to the initiation of different cracks are shown. The experimental results reveal that the decisive design criterion for keyed shaft-hub connections is dependent from the shaft material strength. Keyed shaft-hub connections with shafts made of low-strength steel fail via maximum permissible pressure in the keyway, thus consequently via an unacceptable plastic deformation of the keyway. Keyed shaft-hub connections with shafts made of higher strength steel fail via a crack at the shaft without prior relevant plastic deformation of the keyway. Both design criterions can be handled in the design of keyed shaft-hub connections with different internationally recognized German standards (DIN 743 and DIN 6892). Both standards have their miscellaneous shortcomings and potential improvements will be pointed out. In addition, the strong notch effect causes that the higher material quality of the shaft material does not result in a higher load capacity of the entire component.

Development of an innovative intrarenal pressure regulation system for mini-PCNL: A preliminary study.

Introduction:Miniaturized percutaneous nephrolithotomy (mini-PCNL) requires saline irrigation at high-pressures to maintain visual clarity. However, this may raise the intrarenal pelvic pressures (IRPs) beyond a safe range and may result in a higher complication rate. The aim of this study was to make and validate an automated pressure saline irrigation system to regulate IRPs during mini-PCNL.Materials and Methods:A ureteric catheter was connected to an urodynamic machine and the minimum, maximum, and average IRPs reached during a standard 15 Fr mini-PCNL were measured in ten cases. Next, an intrarenal pressure regulation system (IPRS) was conceptualized, designed, patented, and constructed. IPRS was then tested on a mannequin model using the routine instruments. Lastly, the IPRS was evaluated on – five cases of 15 Fr mini-PCNL. The mean maximum IRP as recorded in the baseline data was set as the maximum permissible pressure on IPRS. The efficacy of IPRS was assessed by measuring the IRP, recorded in parallel, on both the IPRS and the urodynamic machine at various stages of the procedure.Results:The mean maximum IRP reached during baseline evaluation was 25 cm of water which was set as the maximum permissible limit of the IPRS. Evaluation of the IRPS on mannequin models and validation clinical cases showed that IPRS measured the IRP accurately and prevented the pressure surge above the set limits Overall, higher IRPs were recorded during stone pulverization as compared to the other surgical steps.Conclusions:The current IPRS is the first of its kind open platform, portable, automated pressure saline irrigation system. It precisely monitors and controls the IRP and has the potential to reduce the irrigation pressure-related complications.

Mission Innovation task force reports on enabling Gigatonne-scale CO2 storage

Mission Innovation task force reports on enabling Gigatonne-scale CO2 storage

Geoinformational Mapping of Landscapes in the Northwestern Part of Western Siberia Using the Hansen Mosaic Dataset

Presented are the technique and results of studying the landscape structure of the north-west of Western Siberia on the basis of the Hansen mosaic dataset consisting of elements covering the entire territory of the Earth. To study this area used a synthesis of classical methods of thematic system mapping as described in the doctrine of geosystems of V. B. Sochava, and automated interpretation of remote sensing data and mapping using GIS technologies. The method of geoinformational mapping of the landscape structure with the use of MultiSpec and Quantum GIS software programs for the purpose of drawing up real-time raster landscape maps is shown. In drawing up the map and the legend, the principle of geomic system-hierarchical representation of the territory as a complex multi-level “bottom-up” structure from topological-level geosystems (groups and classes of landscape facies) to regional-level geosystems (geoms, groups and classes of geoms) was used. Compilation of operational raster landscape maps of the north-west of Western Siberia involved multilevel automated interpretation of the Hansen mosaic dataset and mapping of areas (clusters) on images with different brightness characteristics, with the landscape structure of key areas and stationary physical and geographical profiles. A characteristic of this approach also implies using a dynamic classification of geosystems based on the study of their variable states. Such an approach permits a monitoring of changes in landscape structure and its areas and the intensity of anthropogenic impacts on forest and marsh landscapes, and determination of permissible pressure on geosystems in areas with high technogenic pressure of the oil and gas complex represented by the north-west of Siberia. An automated processing of data based on a supervised classification of territorial objects allows for the elimination of inaccuracies arising in visual image interpretation. Raster landscape maps can be used both for a further generation of vector maps and as a real-time information base for purposes of environmental management and protection.

Numerical investigation of a premixed combustion large marine two-stroke dual fuel engine for optimising engine settings via parametric runs

As the environmental regulations have become more stringent, the shipping industry has been focusing on more efficient and environmentally friendly means of propulsion and electric power generation. In this respect, dual fuel engines, which operate either in diesel mode or dual fuel (DF) mode by burning diesel fuel or natural gas and pilot diesel fuel to initiate ignition respectively, has become one of the most promising solutions as their dual fuel operation leads to reduced nitrogen oxide (NOx), carbon dioxide (CO2), as well as almost elimination of particulate matter (PM) and sulphur oxide (SOx) emissions. The present study focuses on the comprehensive investigation of a large marine two-stroke dual fuel engine of the low gas pressure concept by using the GT-Power software. Appropriate combustion, scavenging, heat transfer and friction models were used to fully represent the engine performance and emissions characteristics, whereas a knocking model was employed to characterise the engine abnormal combustion. The simulation results were initially validated against the manufacturer data and subsequently, the entire engine envelope in both operating modes was simulated. The derived results were used for analysing and discussing the engine operation, performance and emissions as well as for comparing the two operating modes in terms of the turbocharger matching. In addition, a parametric investigation was performed in the dual fuel mode and the results were used for identifying the settings that can further optimise the engine operation in terms of CO2 and NOx emissions trade-off. The results indicate that the CO2 and NOx emissions can be simultaneously reduced; however, the engine optimisation in the high load region is challenging due to the permissible cylinder pressure constraint.