Computation of the Turbulent Flow in an Internal Combustion Engine During Compression

1981 ◽  
Vol 103 (1) ◽  
pp. 75-81 ◽  
Author(s):  
P. S. Bernard
Keyword(s):  
Internal Combustion Engine ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Dimensional Model ◽  
Vorticity Field ◽  
Dynamical Equations ◽  
Compression Stroke ◽  
Dominant Feature ◽  
Mean And Variance ◽  
The Mean

A set of closed dynamical equations for the mean and variance of the turbulent vorticity field are used to study the piston driven flow in a two-dimensional model of an internal combustion engine cyclinder during the compression stroke. A dominant feature of the flow is observed to be the development of large corner vortices. In their vicinity intense production of turbulence occurs which locally greatly exceeds that resulting from the compression of intake generated turbulence. A comparison of the flow field at two strokes to bore ratios is made.

Turbulence Anisotropy Investigations in an Internal Combustion Engine

2021 ◽  
Author(s):  
James R MacDonald ◽  
Claudia Fajardo
Keyword(s):  
Internal Combustion Engine ◽  
Isotropic Turbulence ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Two Dimensional ◽  
Velocity Data ◽  
Compression Stroke ◽  
Turbulence Anisotropy ◽  
Anisotropy Tensor ◽  
Component Velocity

Abstract The assumption of isotropic turbulence is commonly incorporated into models of internal combustion engine (ICE) in-cylinder flows. While preliminary analysis with two-dimensional velocity data indicates that the turbulence may tend to isotropy as the piston approaches TDC, the validity of this assumption has not been fully investigated, partially due to lack of three-component velocity data in ICEs. In this work, the velocity was measured using two-dimensional, three-component (2D-3C) particle image velocimetry in a single-cylinder, motored, research engine to investigate the evolution of turbulence anisotropy throughout the compression stroke. Invariants of the Reynolds stress anisotropy tensor were calculated and visualized, through the Lumley triangle, to investigate turbulence states. Results showed the turbulence to be mostly anisotropic, with preferential tendency toward 2D axisymmetry at the beginning of the compression stroke and approaching isotropy near top-dead-center. Findings provide new insights into turbulence in dynamic, bounded flows to assist with the development of physics-based, quantitative models.

Analysis of Biodiesel Spray Combustion in Internal-Combustion Engine using Multidimensional Models

2021 ◽  
Vol 13 (4) ◽  
Author(s):  
Qiuyu Zheng ◽  
Xu Wang ◽  
Yi Liu ◽  
Feng Jiang ◽  
Tianqi Liu
Keyword(s):  
Internal Combustion Engine ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Phase Control ◽  
Combustion Characteristics ◽  
Liquid Fuels ◽  
Spray Combustion ◽  
Dimensional Model ◽  
Fuel Temperature ◽  
Ic Engine

With the rapid scale expansion of the first generation of bio-liquid fuels, its impact on the prices of agricultural products, food security and the environment has begun to emerge and attracted extensive attention from governments and academia. A new multi-dimensional model of biodiesel spray combustion in an internal combustion (IC) engine is designed. Firstly, the BP neural network mining model is used to extract the spray combustion data of the IC engine. Then, based on the combustion data of biodiesel load in an internal combustion engine, burning rate and heat release, the principle of spray combustion of biodiesel is analyzed. Finally, from the two aspects of gas-phase control and liquid phase control, a multi-dimensional model of biodiesel spray combustion in IC engine is established and the spray combustion characteristics of biodiesel in IC engine are analyzed. The research results show that the model can effectively analyze the effect of load and fuel temperature on the spray combustion characteristics of biodiesel and the results of the model are almost the same as the actual data and the calculation accuracy is high. It is an effective method for studying the spray combustion characteristics of biodiesel.

Turbulence Anisotropy Investigations in an Internal Combustion Engine

2020 ◽  
Author(s):  
James R. MacDonald ◽  
Claudia M. Fajardo
Keyword(s):  
Internal Combustion Engine ◽  
Isotropic Turbulence ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Two Dimensional ◽  
Velocity Data ◽  
Compression Stroke ◽  
Turbulence Anisotropy ◽  
Anisotropy Tensor ◽  
Component Velocity

Abstract The assumption of isotropic turbulence is commonly incorporated into models of internal combustion engine (ICE) in-cylinder flows. While preliminary analysis with two-dimensional velocity data indicates that the turbulence may tend to isotropy as the piston approaches TDC, the validity of this assumption has not been fully investigated, partially due to lack of three-component velocity data in ICEs. In this work, the velocity was measured using two-dimensional, three-component (2D-3C) particle image velocimetry in a single-cylinder, motored, research engine to investigate the evolution of turbulence anisotropy throughout the compression stroke. Invariants of the Reynolds stress anisotropy tensor were calculated and visualized, through the Lumley triangle, to investigate turbulence states. Results showed the turbulence to be mostly anisotropic, with preferential tendency toward 2D axisymmetry at the beginning of the compression stroke and approaching isotropy near top-dead-center. Findings provide new insights into turbulence in dynamic, bounded flows to assist with the development of physics-based, quantitative models.

scholarly journals Differential equations for calculating gas exchange in an internal combustion engine

2021 ◽  
Vol 264 ◽  
pp. 01003
Author(s):  
Zakirjon Musabekov ◽  
Jamshid Khakimov ◽  
Ergashev Botir
Keyword(s):  
Pressure Drop ◽  
Gas Exchange ◽  
Internal Combustion Engine ◽  
Flow Rate ◽  
Combustion Engine ◽  
Flow Characteristics ◽  
Maximum Flow ◽  
Internal Combustion ◽  
Dimensional Model ◽  
Short Period

Considering the unsteadiness of the flow in the valve channels and windows of the internal combustion engine in combination with limiting the maximum flow rate allows you to take into account the flow characteristics in the exhaust systems of forced engines. Thus, the calculation according to the above method allows us to obtain by calculation, observed in experiments, the reverse pressure drop in the short period of the end of the free release, the validity of using a modified 0-dimensional model of gas exchange, even for engines with long manifolds, where the Strophe number is less than 8.

АКУСТИЧНА ПОМІТНІСТЬ БЕЗПІЛОТНИХ ЛІТАЛЬНИХ АПАРАТІВ З СИЛОВИМИ УСТАНОВКАМИ НА БАЗІ ПОРШНЕВИХ ДВИГУНІВ

2020 ◽  
pp. 62-80
Author(s):  
В. В. Руденко ◽  
И. В. Калужинов ◽  
Н. А. Андрущенко
Keyword(s):  
Control System ◽  
Internal Combustion Engine ◽  
Power Plants ◽  
Combustion Engine ◽  
Spectral Characteristics ◽  
Experimental Studies ◽  
Internal Combustion ◽  
Detection Range ◽  
Acoustic Signature ◽  
Static Conditions

The presence in operation of many prototypes of UAVs with propeller propellers, the use of such devices at relatively low altitudes and flight speeds makes the problem of noise reduction from UAVs urgent both from the point of view of acoustic imperceptibility and ecology.The aim of the work is to determine a set of methods that help to reduce the visibility of UAVs in the acoustic range. It is shown that the main source of noise from the UAV on the ground is the power plant, which includes the engine and the propeller. The parameters of the power plants influencing the processes that determine the acoustic signature of the UAV were investigated. A comprehensive analysis of the factors affecting visibility was carried out. The power plants include two-stroke and four-stroke engines, internal combustion and two-blade propellers. The use of silencers on the exhaust of the internal combustion engine was considered. The spectral characteristics of the acoustic fields of the propeller-driven power plants for the operating sample of the UAV "Eco" were obtained. The measurements were carried out in one-third octave and 1/48 octave frequency bands under static conditions. The venue is the KhAI airfield. Note that the propellers that were part of the power plants operated at Reynolds numbers (Re0,75<2*105), which can significantly affect its aerodynamic and acoustic characteristics. It is shown that when choosing a UAV control system, one should take into account the fact that two-stroke piston engines are the dominant source in the noise of propeller-driven control systems in the absence of a hood and mufflers in the intake and exhaust tracts. The use of a four-stroke internal combustion engine significantly reduces the noise of the control system. In the general case, the position of the boundaries of the zone of acoustic visibility of a UAV at the location of the observer is determined by the ratio between the intensity of acoustic radiation perceived by the observer from the UAV and the intensity of sound corresponding to the natural acoustic background and depends on the degree of manifestation of acoustic effects accompanying the propagation of sound in a turbulent atmosphere - the refraction of sound waves. Absorption and dissipation of acoustic energy. The calculation and comparison of the UAV detection range was carried out taking into account the existing natural maskers.The results of experimental studies are presented that allow assessing the degree of acoustic signature of the UAV. A set of measures aimed at reducing the intensity of the acoustic signature of the UAV in various regions of the radiation spectrum has been determined.

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