Investigation of Swirl Ratio Impact on In-Cylinder Flow in a SIDI Optical Engine

Advanced powertrain technologies have improved engine performance with higher power output, lower exhaust emission, and better controllability. Chief among them is the development of spark-ignition direct-injection (SIDI) engines in which the in-cylinder processes control the air flow motion, fuel-air mixture formation, combustion, and soot formation. Specifically, intake air with strong swirl motion is usually introduced to form a directional in-cylinder flow field. This approach improves the mixing process of air and fuel as well as the propagation of flame. In this study, the effect of intake air swirl on in-cylinder flow characteristics was experimentally investigated. High speed particle image velocimetry (PIV) was conducted in an optical SIDI engine to record the flow field on a swirl plane. The intake air swirl motion was achieved by adjusting the opening of a swirl ratio control valve which was installed in one of the two intake ports in the optical engine. Ten opening angles of the swirl ratio control valve were adjusted to produce an intake swirl ratio from 0.55 to 5.68. The flow structures at the same crank angle degree, but under different swirl ratio, were compared and analyzed using proper orthogonal decomposition (POD). The flow dominant structures and variation structures were interpreted by different POD modes. The first POD mode captured the most dominant flow field structure characteristics; the corresponding mode coefficients showed good linearity with the measured swirl ratio at the compression stroke when the flow was swirling and steady. During the intake stroke, strong intake air motion took place, and the structures and coefficients of the first modes varied along different swirl ratio. These modes captured the flow properties affected by the intake swirl motion. Meanwhile, the second and higher modes captured the variation feature of the flow at various crank angle degrees. In summary, this paper demonstrated a promising approach of using POD to interpret the effectiveness of swirl control valve on in-cylinder swirl flow characteristics, providing better understanding for engine intake system design and optimization.

Download Full-text

Investigation of Swirl Ratio Impact on In-Cylinder Flow in an SIDI Optical Engine

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4032419 ◽

2016 ◽

Vol 138 (8) ◽

Cited By ~ 7

Author(s):

Hanyang Zhuang ◽

David L. S. Hung ◽

Jie Yang ◽

Shaoxiong Tian

Keyword(s):

High Speed ◽

Soot Formation ◽

Flow Characteristics ◽

Engine Performance ◽

Control Valve ◽

Swirl Flow ◽

Exhaust Emission ◽

Swirl Ratio ◽

Optical Engine ◽

Cylinder Flow

Advanced powertrain technologies have improved engine performance with higher power output, lower exhaust emission, and better controllability. Chief among them is the development of spark-ignition direct-injection (SIDI) engines in which the in-cylinder processes control the air flow motion, fuel–air mixture formation, combustion, and soot formation. Specifically, intake air with strong swirl motion is usually introduced to form a directional in-cylinder flowfield. This approach improves the mixing process of air and fuel as well as the propagation of flame. In this study, the effect of intake air swirl on in-cylinder flow characteristics was experimentally investigated. High-speed particle image velocimetry (PIV) was conducted in an optical SIDI engine to record the flowfield on a swirl plane. The intake air swirl motion was achieved by adjusting the opening of a swirl ratio (SR) control valve which was installed in one of the two intake ports in the optical engine. Ten opening angles of the SR control valve were adjusted to produce an intake SR from 0.55 to 5.68. The flow structures at the same crank angle degree (CAD), but under different SR, were compared and analyzed using proper orthogonal decomposition (POD). The flow dominant structures and variation structures were interpreted by different POD modes. The first POD mode captured the most dominant flowfield structure characteristics; the corresponding mode coefficients showed good linearity with the measured SR at the compression stroke when the flow was swirling and steady. During the intake stroke, strong intake air motion took place, and the structures and coefficients of the first modes varied along different SR. These modes captured the flow properties affected by the intake swirl motion. Meanwhile, the second and higher modes captured the variation feature of the flow at various CADs. In summary, this paper demonstrated a promising approach of using POD to interpret the effectiveness of swirl control valve on in-cylinder swirl flow characteristics, providing better understanding for engine intake system design and optimization.

Download Full-text

Systematic Multi-Index Validations of SIDI Engine Flow Field LES Computations Using Crank Angle-Resolved PIV Measurements

ASME 2019 Internal Combustion Engine Division Fall Technical Conference ◽

10.1115/icef2019-7145 ◽

2019 ◽

Cited By ~ 1

Author(s):

Mengqi Liu ◽

Fengnian Zhao ◽

Xuesong Li ◽

Min Xu ◽

Zongyu Yue ◽

...

Keyword(s):

Flow Field ◽

Flow Fields ◽

Model Verification ◽

Piv Measurements ◽

Multi Index ◽

Global Indices ◽

Comparison Results ◽

Crank Angle ◽

Flow Field Characteristics ◽

Cylinder Flow

Abstract In-cylinder flow fields make significant impacts on the fuel atomization, fuel mixture formation, and combustion process in spark ignition direct injection (SIDI) engines. In recent years, model-based simulation approaches are preferred in regard to investigating the transient in-cylinder flow field characteristics. Most commonly, the simulation models are validated using single representative flow field at a typical crank angle measured by particle image velocimetry (PIV). However, it provides only limited knowledge about the flow field which is highly three-dimensional and of transient nature. In this study, crank angle-resolved PIV measurements are conducted on three distinct planes inside the cylinder to capture the transient process of flow field characteristics which vary with the crank angle. These three planes consist of one tumble plane through the spark plug tip, one tumble plane along two intake ports, and one swirl plane at 30 mm below the cylinder head. Large eddy simulation (LES) is employed for the numerical computations using the CONVERGE codes. On the basis of large datasets for both temporal and spatial domains, a multi-index systematic validation approach is conducted. Crank angle-resolved calculations of global indices and local indices are implemented using the flow fields velocity data obtained from both PIV and LES on select planes. Global indices reveal the trends in similarities of different crank angle degrees and locations, while local indices give the detail comparison results. In summary, with the systematic multi-index validation approach, the crucial crank angle degrees and locations for model verification will be detected. Furthermore, the corresponding critical flow features are analyzed. Practical guideline of flow field validation is proposed.

Download Full-text

Numerical Simulation Study of the Influence of Structural Parameters of Combustion Chamber on In-Cylinder Flow Field of Diesel Engine

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.860-863.1729 ◽

2013 ◽

Vol 860-863 ◽

pp. 1729-1732

Author(s):

Guo Cheng Li ◽

Ping Sun ◽

Peng Hu

Keyword(s):

Diesel Engine ◽

Flow Field ◽

Combustion Chamber ◽

Structural Parameters ◽

Volume Ratio ◽

Initial Boundary ◽

Swirl Flow ◽

Swirl Ratio ◽

Depth Ratio ◽

Cylinder Flow

Based on the entity model of the type 4B26 diesel engine, calculated by CFD FIRE and combined with the software BOOST for the initial boundary conditions, the influence of combustion chamber structural parameters, such as boss height, surface-volume ratio and diameter-depth ratio of combustion chamber, on in-cylinder flow field of diesel engine was investigated. The results show that the influence of the boss height on flow field in the cylinder and the transient swirl ratio is obvious, and increasing the boss height is beneficial to urge the formation of mixture rapidly. Reducing the surface-volume ratio is beneficial for improving the maximum transient swirl ratio, and the air strength maintains well also, but has little influence to the retentivity of the swirl intensity. Meanwhile, reducing the diameter-depth ratio does not only improves the air flow movement strengthen in the combustion chamber, but also enhances the maximum transient swirl ratio, and the retentivity of swirl flow movement is satisfying.

Download Full-text

The Three-Dimensional Unsteady Numerical Analysis of the Internal Flow Field of the New Control Valve

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.980.112 ◽

2014 ◽

Vol 980 ◽

pp. 112-116

Author(s):

Dong Yue Qu ◽

Jia Lei Xu ◽

Yang Yang Huang ◽

Xiao Zeng Xie

Keyword(s):

Flow Field ◽

Three Dimensional ◽

Flow Characteristics ◽

Control Valve ◽

Internal Flow ◽

Pulse Frequency ◽

Computational Fluid Dynamics Cfd ◽

Steam System ◽

Normal Work ◽

Vibration Noise

The medium flow of control valve is a typical complex unsteady flow, the internal flow is very unstable which leads to trim or body with vibration of different amplitude, therefore, control valve has been a failure-prone components in the turbine inlet steam system. This paper take the new valve as the research object, by computational fluid dynamics (CFD) software, the numerical simulation of the internal steam steady state flow field of valve normal work a typical opening in the process of opening is made, and obtain the internal flow field visualization distribution and flow characteristics of control valve. Extract unstable place pressure pulsation of the flow field, get the pulse frequency, and provide the basis for the design, optimization and application of low vibration noise control valve.

Download Full-text

Experimental and Modeling Study of the Effect of Manufacturing Deviations on the Flow Characteristics of Tangential Intake Port in a Diesel Engine

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4027557 ◽

2014 ◽

Vol 136 (11) ◽

Cited By ~ 3

Author(s):

Zhen Lu ◽

Tianyou Wang ◽

Shuliang Liu ◽

Zhiqiang Lin ◽

Yiyong Han

Keyword(s):

Diesel Engine ◽

Cfd Simulation ◽

Combustion Engine ◽

Flow Characteristics ◽

Intake Port ◽

Swirl Ratio ◽

Machining Processes ◽

Computational Fluid Dynamics Cfd ◽

Inclined Angle ◽

Cylinder Flow

The intake port flow characteristics in an internal combustion engine significantly affect its power output, fuel economy, and emissions. To optimize the flow characteristics in the intake port, increasing attention has been paid to its design process. However, the casting and machining processes of the intake port are underappreciated, which may introduce significant deviations, leading to undesirable variation of intake port flow and subsequent deterioration in engine combustion and emissions. In this paper, steady flow tests were carried out on a four-valve diesel engine to investigate how and to what extent the casting and machining deviations of the intake port influence the in-cylinder flow characteristics. The results show that these deviations lead to the variation of swirl ratio up to 20%. Then, computational fluid dynamics (CFD) simulation was conducted for understanding the reason. It is indicated that higher tolerance is needed during the casting and machining processes. For example, in order to control the variation of swirl ratio within 10%, the inclined angle should be controlled at less than 1 deg, the eccentric distance should be restricted to less than 0.5 mm, and the swelling thickness should be limited to less than 1 mm.

Download Full-text

Multi-plane time-resolved Particle Image Velocimetry (PIV) flow field measurements in an optical Spark-Ignition Direct-Injection (SIDI) engine for Large-Eddy Simulation (LES) model validations

Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles ◽

10.2516/ogst/2019022 ◽

2019 ◽

Vol 74 ◽

pp. 52 ◽

Cited By ~ 4

Author(s):

Fengnian Zhao ◽

Mengqi Liu ◽

Penghui Ge ◽

David L.S. Hung ◽

Xuesong Li ◽

...

Keyword(s):

Flow Field ◽

Direct Injection ◽

Flow Characteristics ◽

Field Measurements ◽

Flow Fields ◽

Eddy Simulation ◽

Image Velocimetry ◽

Local Comparison ◽

Cylinder Flow ◽

Les Model

In-cylinder flow characteristics play a significant role in the fuel–air mixing process of Spark-Ignition Direct-Injection (SIDI) engines. Typically, planar Particle Image Velocimetry (PIV) is used to measure a representative velocity field sectioning through the center plane of the engine cylinder. However, a single flow field offers very limited perspective regarding the Three-Dimensional nature of the flow fields. Since the in-cylinder flow is stochastically complex, large datasets of flow field measurements along multiple planes are needed to provide a complete panoramic understanding of the flow dynamics. In this study, a high-speed PIV is applied to measure the crank-angle resolved flow fields inside a single-cylinder four-valve optical SIDI engine. Five flow fields along different tumble planes are captured. These five planes include two orthogonal planes cutting through the spark plug tip, two parallel planes sectioning through middle point of the intake and exhaust valves, and one plane through the centers of two intake valves. In addition, numerical computations are carried out with Large-Eddy Simulation (LES) model in CONVERGE. With the guidance from multi-plane PIV measurements, a novel validation approach is proposed in this study. The quantitative analysis and comparison between LES simulations and PIV experiments are divided in terms of global and local comparison indices. The global comparison indices provide a quantitative single value to quickly check the overall similarity of velocity directions and magnitudes between PIV and LES results of a specific individual plane. The local comparison indices further evaluate the similarity between the flow fields of LES and PIV point by point to identify any dissimilar regions and vortex features, which are likely to indicate the complex flow structures at low-speed regions. In summary, not only can the combined data analysis approach provide a reliable way for LES model validations, it can also reveal the physical quantifications of the complex in-cylinder flow characteristics.

Download Full-text

Numerical Study on Mechanical Characteristics of Steam Turbine Valve Disc

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.572.319 ◽

2013 ◽

Vol 572 ◽

pp. 319-322

Author(s):

Dong Yue Qu ◽

Zhong Yuan Guo ◽

Chong Liu

Keyword(s):

Flow Field ◽

Axial Force ◽

Numerical Study ◽

Pressure Ratio ◽

Flow Characteristics ◽

Control Valve ◽

Internal Flow ◽

Simulation Method ◽

Complex Flow ◽

Valve Stem

The instability flow in the control valve often lead to abnormal vibration, the valve wear and the valve stem destruction, also lead to pressure loss. The flow in the control valve show complex flow regime distribution and variation, it is a typical unsteady flow. Therefore, it is necessary to theoretical calculation and qualitative analyses the flow field of valve by the numerical simulation method. In this paper, we study on the axial force of valve stem that caused by the fluid pulsation pressure. Establishing the flow field model of the control valve, generating the computational grid through the pre-processor, using the CFD software to do discretized and solved, getting visualization graphics of the internal flow field. Study the changes of the flow characteristics according to different pressure ratio, getting the variation characteristic of axial force. Provide the basis for subsequent optimization and design of the low vibration control valve.

Download Full-text

Combustion Study of Polyoxymethylene Dimethyl Ethers and Diesel Blend Fuels on an Optical Engine

Energies ◽

10.3390/en14154608 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4608

Author(s):

Jingjing He ◽

Hao Chen ◽

Xin Su ◽

Bin Xie ◽

Quanwei Li

Keyword(s):

Soot Formation ◽

Comprehensive Evaluation ◽

Chemical Properties ◽

Heating Value ◽

Optical Engine ◽

Leading Role ◽

Combustion Duration ◽

Polyoxymethylene Dimethyl Ethers ◽

Lower Heating Value ◽

Lower Heating

Polyoxymethylene dimethyl ethers (PODE) are a newly appeared promising oxygenated alternative that can greatly reduce soot emissions of diesel engines. The combustion characteristics of the PODE and diesel blends (the blending ratios of PODE are 0%, 20%, 50% and 100% by volume, respectively) are investigated based on an optical engine under the injection timings of 6, 9, 12 and 15-degree crank angles before top dead center and injection pressures of 100 MPa, 120 MPa and 140 MPa in this study. The results show that both the ignition delay and combustion duration of the fuels decrease with the increasing of PODE ratio in the blends. However, in the case of the fuel supply of the optical engine being fixed, the heat release rate, cylinder pressure and temperature of the blend fuels decrease with the PODE addition due to the low lower heating value of PODE. The addition of PODE in diesel can significantly reduce the integrated natural flame luminosity and the soot formation under all injection conditions. When the proportion of the PODE addition is 50% and 100%, the chemical properties of the blends play a leading role in soot formation, while the change of the injection conditions have an inconspicuous effect on it. When the proportion of the PODE addition is 20%, the blend shows excellent characteristics in a comprehensive evaluation of combustion and soot reduction.

Download Full-text