Wyniki wyszukiwania - BazTech

1

An experimental study of the effects of cylinder lubricating oils on the vibration characteristics of a two-stroke low-speed marine diesel engine

Wu Gang, Jiang Guodong, Chen Changsheng, Jiang Guohe, Pu Xigang, Chen Biwen

Polish Maritime Research

|

2023

|

nr 4

92--101

EN

Two-stroke, low-speed diesel engines are widely used in large ships due to their good performance and fuel economy. However, there have been few studies of the effects of lubricating oils on the vibration of two-stroke, low-speed diesel engines. In this work, the effects of three different lubricating oils on the vibration characteristics of a low-speed engine are investigated, using the frequency domain, time-frequency domain, fast Fourier transform (FFT) and short-time Fourier transform (STFT) methods. The results show that non-invasive condition monitoring of the wear to a cylinder liner in a low-speed marine engine can be successfully achieved based on vibration signals. Both the FFT and STFT methods are capable of capturing information about combustion in the cylinder online in real time, and the STFT method also provides the ability to visualise the results with more comprehensive information. From the online condition monitoring of vibration signals, cylinder lubricants with medium viscosity and medium alkali content are found to have the best wear protection properties. This result is consistent with those of an elemental analysis of cylinder lubrication properties and an analysis of the data measured from a piston lifted from the cylinder after 300 h of engine operation.

2

Simulation Research of the Influence of Compression Ratio on the Performance of an Aircraft Piston Diesel Engine

Grabowski Łukasz, Karpiński Paweł, Magryta Paweł

Advances in Science and Technology. Research Journal

|

2020

|

Vol. 14, no 3

175--181

EN

In recent years, the opposed-piston engines have become increasingly popular in the automotive and aerospace industries. Therefore, it is necessary to conduct the research on this type of drive. The paper presents the simulation research of a two-stroke opposed-piston diesel engine designed for propulsion of light aircrafts. The influence of the change of the compression ratio on the selected engine performance was investigated (indicated mean effective pressure, peak firing temperature and pressure, specific fuel consumption, power consumed by the compressor). The AVL BOOST software was used to perform the simulation tests. A zero-dimensional engine model equipped with a mechanical compressor was developed. On the basis of the created model, a series of calculations was performed for the assumed values of the compression ratio for four engine operating points: take-off power, maximum continuous power and cruising power at two different altitudes. The obtained results were subjected to a comparative analysis and the most important conclusions connected with the influence of the change in the compression ratio on the achieved performance were presented.

3

Modelling of Dynamic Interactions in the Fuel Rail for the Aircraft Diesel Engine

Sochaczewski Rafał, Magryta Paweł

Advances in Science and Technology. Research Journal

|

2020

|

Vol. 14, no 4

168--176

EN

The paper reports a computer model for simulating dynamic responses in fuel rail of aircraft diesel engine. The fuel system was designed for use in a two-stroke compression-ignition engine with opposite pistons. The methodology of building a fuel system model in the AVL Hydsim program and the results of simulation studies were presented. Determination of dynamic phenomena in the fuel rail required the construction of a model of the entire supply system. It is a common rail system with a three-section positive displacement pump and electromagnetic fuel injectors. The system is also equipped with a PID regulator to maintain the present pressure in the fuel rail. For the purposes of the research, two structures of the fuel rail were developed. They differ in dimensions, spacing of the outlet ports and location of the high-pressure connection. The research allowed determining the interactions between the geometry of the fuel rail and the supply method with the fuel pressure and injector mass flow rate. This will optimise the design of the fuel rail for the three-cylinder engine power supply system.

4

Experimental research of two stroke aircraft diesel engine

Grabowski Łukasz, Karpiński Paweł, Barański Grzegorz

Combustion Engines

|

2019

|

R. 58, nr 4

75--79

EN

This paper presents the results of experimental studies of the opposed-piston diesel engine. This engine was designed during one of the stages of the research on a new-type drive unit for gyrocopter applications. In order to conduct research, a special test stand as well as control and measurement systems were developed. As part of the work on the engine, the fuel injection system, engine temperature control system and measurement systems were designed. In addition, a computer program has been developed for the fuel injection system control (injectors, valves fuel pressure regulators). The paper presents the results of the preliminary tests for a single value of engine speed (1500 rpm) and three values of load defined by torque. The measured value of the indicated pressure made it possible to calculate the maximum pressure. The results obtained from the bench tests were analyzed.

5

Analysis of the applicability of a common rail pump for an aircraft engine

Sochaczewski Rafał, Szlachetka Marcin, Wendeker Mirosław, Karpiński Paweł

Combustion Engines

|

2019

|

R. 58, nr 4

192--197

EN

The paper presents an analysis of the possibility of using a common rail pump to supply an aircraft compression-ignition engine. It is an engine with a two-stroke cycle, three cylinders, opposing pistons and 100 kW power. Its each combustion chamber is supply by one or two injectors controlled by electromagnetic valves. In order to assess the possibility of using a common rail pump, four high-pressure pumps were tested on a bench. They are piston pumps differing in the number and geometry of their pumping sections. The analysis included the pumping output, the torque on the pump drive shaft and the power needed to drive the pump. The weight and overall dimensions of the pump were also considered, including the arrangement of the pumping sections and the way the drive is transmitted. The research allowed to optimize the engine power supply system depending on fuel demand and the way the pump is mounted on the engine.

6

The swirl ratio influence on combustion process and heat transfer in the opposed piston compression-ignition engine

Tulwin T., Wendeker M., Czyż Z.

Combustion Engines

|

2017

|

R. 56, nr 3

3--7

EN

In order to maximise engine heat efficiency an engines charge flow must be properly designed -especially its swirl and tumble ratio. A two-stroke compression-ignition opposed piston engine reacts to engine swirl differently compared to a standard automotive engine with axially symmetric combustion chamber. In order to facilitate direct fuel injection, high-pressure injectors must be positioned from the side of combustion chamber. Depending on the combustion chamber geometry the swirling gases impact greatly how the injection stream is formed. If the deformation is too high the high temperature combustion gases can hit the piston surface or get into gaps between the pistons. This greatly affects the heat lost to the pistons and raises their local temperature. More atomised injection stream is more prone to swirling gas flow due to its reduced droplet size and momentum. The paper presents simulation results and analyses for different intake process induced swirl ratios and different types of combustion chambers in an experimental aviation opposed piston engine.

7

Modeling a fuel injector for a two-stroke diesel engine

Sochaczewski R., Czyż Z., Siadkowska K.

Combustion Engines

|

2017

|

R. 56, nr 3

147--153

EN

This paper discusses the modeling of a fuel injector to be applied in a two-stroke diesel engine. A one-dimensional model of a diesel injector was modeled in the AVL Hydsim. The research assumption is that the combustion chamber will be supplied with one or two spray injectors with a defined number of nozzle holes. The diameter of the nozzle holes was calculated for the defined options to provide a correct fuel amount for idling and the maximum load. There was examined the fuel mass per injection and efficient flow area. The studies enabled us to optimize the injector nozzle, given the option of fuel injection into the combustion chamber to be followed.

8

Investigation into the effect of bore/stroke ratio on a single cylinder two stroke opposed piston engin

Alqahtani A. M., Wyszynski M. L., Mazuro P.

Journal of KONES

|

2016

|

Vol. 23, No. 2

9--16

EN

Opposed-piston (OP) engine’s promising fuel efficiency has attracted the interest of automotive industry in the recent years. The opposed-piston two-stroke (OP2S) engine technology heightens this fuel efficiency benefit and offers advances in structure, power density and thermal efficiency whilst sustaining its lower cost and weight. Today thermodynamic modelling remains an indispensable and cost effective route in the development and optimisation of internal combustion engines (ICEs). To achieve this goal, the OP2S engine is simulated and validated against experimental results in AVL Boost™, which is hailed as one of the most reliable and advanced engine simulation tools. Detailed analyses of the piston dynamics, heat release, scavenging and heat transfers are highlighted in discrete sections of this paper. Having compared distinct heat release models, the Wiebe 2-Zone model emerged efficacious in replicating the heat release characteristics of the PAMAR™ engine. In comparing the numerical and experimental results, the simulation revealed minimal differences in peak pressure, peak temperature and maximum pressure raise rate, under ±2.5% differences for indicated power, IMEP, indicated thermal efficiency (ITE) and ISFC. Subsequently, confidence taken from the validated numerical model is then deployed to investigate the effect of stroke-to-bore (S/B) ratio on OP2S performance. Three combinations of S/B ratios (0.5, 1.25, and 1.69) with identical swept volume are analysed in this study. Utilisation of the validated model ensured the standardisation of intake, exhaust and the combustion systems in order to isolate the effects of S/B ratio. Results indicate that heat losses decrease with increasing S/B ratio because of the reduced surface area-to-volume in the cylinder. Consequently, an improvement in ITE and mechanical efficiency is observed with reduced ISFC for higher S/B ratios. A tendency of upsurge in combustion efficiency is also evident for higher S/B ratio due to reduced heat transfer near minimum volume of the combustion chamber.

9

Various designs of the two-stroke engine heads with the valve flushed system

Łoza Ł., Kaźmierczak A., Borkowska J., Skorupa P., Krakowian K., Cienciała M.

Journal of KONES

|

2015

|

Vol. 22, No. 4

187--190

EN

The two-stroke engines have never acquired the popularity of the four-stroke engines due to their inherent performance limitations. The tasks of many engineering teams were to find the basic causes, which resulted in the inferior performance of these engines. Today’s task is to build a two-stroke engine whose performance could match that of a four-stroke engine in areas of common use. The most typical performance problems of a two-stroke engine are high petrol consumption caused by low efficiency, toxic by-products of combustion being emitted into the atmosphere (caused by oil present in the petrol), and uneven and loud engine noise. The greatest challenge is to achieve a good chamber purge during one stroke in which the fresh fuel mixture flows through the piston-controlled inlet port while at the same time the fumes are being exhausted through the outlet port. This in contrast with the four-stroke engines where the intake and exhaust are each done with two separate strokes. From the energy point of view, the two-stroke engine is not efficient because a certain amount of fresh fuel is being wasted in the exhaust fumes. We propose to replace the piston-controlled cam with the valve-flushed system, which will cause the combustion process to become more efficient. The purpose of this paper is to present various designs of the engine heads and analyse their performance. The goal of this proposal is to choose the best combination of these engine heads in order to achieve the optimum overall engine performance.