The Interactions of In-Cylinder Flow and Fuel Spray in a Gasoline Direct Injection Engine With Variable Tumble

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Xianhui Zhang ◽  
Tianyou Wang ◽  
Ming Jia ◽  
Wei Li ◽  
Lei Cui ◽  
...  
Keyword(s):  
Shear Strain ◽  
Large Scale ◽  
Direct Injection ◽  
Cone Angle ◽  
Gasoline Direct Injection ◽  
Shear Strain Rate ◽  
Maximum Shear Strain ◽  
The Mean ◽  
Pod Analysis ◽  
Coherent Part

Particle image velocimetry (PIV) system was used to measure the tumble structure of the in-cylinder airflow in a four-valve optical gasoline direct injection (GDI) engine. The tumble ratio was controlled by a flap in the manifold and a baffle in the intake port. With proper orthogonal decomposition (POD) method, the velocity field was decomposed into four parts, i.e., the mean, coherent, transitional, and turbulent. The effect of tumble motion on the cycle-to-cycle variation (CCV) of airflow and spray was investigated by calculating the shear strain vorticity. The results indicate that the flow structure can be effectively changed through the combination of flap and baffle by forming a single large-scale tumble flow with the tumble ratio three times higher than the original one. According to POD analysis, it is revealed that the large-scale strong tumble motion leads to the energy occupation ratio of the mean part greatly increase by up to 30%, while the energy transferred to the coherent part is reduced. The above process also decreases the CCV of the coherent part by 50%; thus, the CCV of the whole airflow in the cylinder can be suppressed. A single large-scale tumble increases the maximum shear strain rate up to 2400 s−1. Meanwhile, the maximum vorticity increases to about 6000 s−1 by rolling up of the airflow. The contact area between spray droplets and air becomes larger, and the momentum exchanges between them contribute to wider sprays cone angle and shorter penetration distance when the flap is closed. The statistics of the measurements illustrate that a single large-scale tumble can promote the formation of homogeneous mixture and reduce the fluctuation between multicycles.

Design and development of a new gasoline direct swirl injector

2002 ◽  
Vol 216 (10) ◽  
pp. 831-839
Author(s):  
Y K Park ◽  
S Y Moon ◽  
C W Lee
Keyword(s):  
Direct Injection ◽  
Cone Angle ◽  
Gasoline Direct Injection ◽  
Spray Angle ◽  
Design Parameters ◽  
Drop Diameter ◽  
Cone Type ◽  
Swirl Injector ◽  
The Mean ◽  
Inclined Angle

Numerical and experimental analyses were carried out to design and develop the optimum geometry of a gasoline direct swirl injector. In the numerical analysis, the needle cone angle, swirler inclined angle and needle lift were changed with mass flowrate as design parameters to determine the optimum sizes. The critical sizes of the needle cone angle, swirler inclined angle and needle lift are 140°, 120° and 100 μm respectively. Thus, the optimum sizes may be 130°, 110° and 80 °m respectively. Experiments were performed to observe spray phenomena and to measure the dynamic flowrate, penetration of the spray tip and mainstream, spray angle and the mean drop diameter using an image processing method. The formation of a counter-rotating vortex appears in the steady state as a feature of the high pressure swirl injector spray. The calculated needle cone and swirl inclined angles as well as the cone-type needle reduce the non-swirl and sac volumes of the non-swirl region such that the reduced volumes restrict the penetration of the spray tip. The sizes of the mean drop diameter range from 20μm to 23μm and the spray angles range from 64° to 66°, which satisfy the requirements of a gasoline direct injection engine.

scholarly journals The theory of plane plastic strain for anisotropic metals

1949 ◽  
Vol 198 (1054) ◽  
pp. 428-437 ◽  
Keyword(s):  
Plastic Strain ◽  
Strain Rate ◽  
Shear Strain ◽  
Plane Strain ◽  
Yield Criterion ◽  
Elliptic Functions ◽  
Shear Strain Rate ◽  
Maximum Shear Strain ◽  
Geometrical Properties ◽  
Plane Plastic

A yield criterion and plastic stress-strain relations are formulated for anisotropic metals deformed under conditions of plane strain. The equations are shown to be hyperbolic, the characteristics coinciding with the directions of maximum shear strain-rate. When the anisotropy is uniformly distributed, the variation of the stresses along the characteristics is expressed in terms of elliptic functions, and geometrical properties of the field of characteristics are established. The theory is applied to the problem of indentation by a flat die.

Effect of ultra-high injection pressure up to 50 MPa on macroscopic spray characteristics of a multi-hole gasoline direct injection injector fueled with ethanol

2017 ◽  
Vol 232 (8) ◽  
pp. 1092-1104 ◽  
Author(s):  
Xiang Li ◽  
Yi-qiang Pei ◽  
Jing Qin ◽  
Dan Zhang ◽  
Kun Wang ◽  
...  
Keyword(s):  
High Speed ◽  
Direct Injection ◽  
Cone Angle ◽  
Injection Pressure ◽  
Fuel Mixture ◽  
Gasoline Direct Injection ◽  
Spray Characteristics ◽  
High Injection ◽  
High Injection Pressure ◽  
Wall Impingement

This research systematically studied the effect of injection pressure on macroscopic spray characteristics of a five-hole gasoline direct injection (GDI) injector fueled with ethanol, especially under ultra-high injection pressure up to 50 MPa. The front and side views of sprays were photographed by the schlieren method using a high-speed camera. Various parameters, including spray development stages, cone angle, penetration, area and irregular ratio, were fully analyzed to evaluate macroscopic characteristics of the whole spray and spray core with varying injection pressure. The results demonstrated that the effect of ultra-high injection pressure on macroscopic spray characteristics was significant. As injection pressure increased from 10 MPa to 50 MPa, the occurrence time of branch-like structure decreased; the cone angle increased little; the area increased significantly; the area ratio dropped by 6.4 and 5.8 percentage points on average for the front view and side view spray, respectively. There was a significant increase in the trend for penetration as the injection pressure rose from 10 MPa to 30 MPa. However, this trend became weak when the injection pressure further increased. The penetration ratio under ultra-high injection pressure was slightly higher than it was under 10 or 20 MPa. Ultra-high injection pressure would not obviously raise the possibility of spray/wall impingement, but led to the impingement quantity increasing to some extent. Increasing injection pressure could enhance the vortex scale, finally resulting in better air/fuel mixing quality. Ultra-high injection pressure was a potential way to improve air/fuel mixture homogeneity for a GDI injector fueled with ethanol.

Geodetically derived strain at Shelter Cove, California

1980 ◽  
Vol 70 (3) ◽  
pp. 893-901
Author(s):  
Richard A. Snay ◽  
Michael W. Cline
Keyword(s):  
Shear Strain ◽  
San Francisco ◽  
Geodetic Network ◽  
Geodetic Survey ◽  
Time Interval ◽  
National Geodetic Survey ◽  
Shear Strain Rate ◽  
San Andreas ◽  
The Mean ◽  
Homogeneous Strain

abstract To monitor crustal motion, the National Geodetic Survey observed, during 1976, a small geodetic network in the Shelter Cove area of northern California. This network straddles part of the fault which ruptured during the 1906 San Francisco earthquake. Analysis of the new survey data, combined with observations of a larger 1930 network, yields an estimate of N13.2°W ± 4.5° for the direction of maximum right-lateral shear strain through the area. This value agrees well with the average strike of the straddled fault and with the average strike of the San Andreas Fault's underwater path between Point Arena and Shelter Cove. The mean shear strain rate in this direction is 1.01 ± 0.18 (10−6) rad/yr for the 1930 to 1976 time interval where a region undergoing homogeneous strain more accurately describes the data than models allowing for the existence of surface slippage.

Dynamic Response Analysis and Structure Optimization of GDI Injector based on Mathematical Model

2018 ◽  
Vol 25 (02) ◽  
pp. 1850008
Author(s):  
Xigui Yao ◽  
Zhendong Zhang ◽  
Xiangdong Kong ◽  
Congbo Yin
Keyword(s):  
Gasoline Engine ◽  
Fuel Injection ◽  
Direct Injection ◽  
Cone Angle ◽  
Structure Optimization ◽  
Gasoline Direct Injection ◽  
Needle Valve ◽  
Response Analysis ◽  
Injection Process ◽  
Oscillation Analysis

The purpose of this research is to prevent the abnormal injection process in Gasoline Direct Injection (GDI) injector, realize accurate control of the fuel injection quantity and improve the performance of gasoline engine. The mechanical characteristics of the needle valve in a porous GDI injector is analyzed, the needle dynamics model is established, and the needle oscillation process is simulated with a mechanic-electronic-hydraulic integration method with the help of AMEsim software. The validity of the model is verified. The factors that influence the dynamics of the needle valve are analyzed. The results show that the dynamics of needle movement in GDI injector are mainly affected by the seat cone angle and the moving mass of the needle valve. The comprehensively improved structure of GDI injector is proposed based on the needle oscillation analysis. The simulation results show that the dynamic characteristics in GDI injector’s needle valve can be significantly improved with the optimized new structure. The experimental results of fuel injection flow characteristic and penetration distance show that the reliability and safety of the injector has been enhanced after structure optimization.

Strain patterns of Sichuan and Yunnan, China from GPS data and comparison between seismic and geodetic moment release

2020 ◽  
Author(s):  
Jingyang Zhao ◽  
Yanqiang Wu ◽  
Hongbao Liang ◽  
Kaifu Du
Keyword(s):  
Strain Rate ◽  
Shear Strain ◽  
Earthquake Catalog ◽  
Shear Strain Rate ◽  
The South ◽  
Maximum Shear Strain ◽  
Block Boundary ◽  
The North ◽  
Geodetic Strain ◽  
East West

<p>We processed data from ~600 GPS stations, covering the period 1999-2018, to provide new insights into the crustal motion and deformation of Sichuan and Yunnan, China. We used the derived velocity field to evaluate two-dimensional strain rate tensors, and mapped the main, maximum shear, dilatation, east-west and north-south strain rates.The spatial distribution of the main strain rate in the Sichuan-Yunnan region generally shows an orderly deflection. The minimum principal strain rate is northeastward in the west of the Sichuan-Yunnan block boundary, gradually deflects eastward and southeastward toward the east and south, and returns to the northeast direction until the southwestern edge of Sichuan-Yunnan. This reflects the complex tectonic dynamics background of the study area. The high value of the maximum shear strain rate is mainly distributed along the eastern boundary of the Sichuan-Yunnan block, especially near the Xianshuihe-Xiaojiang fault, where the maximum shear strain rate exceeds 4.0 × 10<sup>-8</sup> / a. The area strain rate in the study region shows that the areas of compression and expansion are comparable, with weak tensions prevailing in the interior and compression in the marginal areas. The strain rate result also shows that the east-west strain rate component in the southern Sichuan-Yunnan is dominated by positive value, and the north is dominated by negative value. It indicates that the east-west deformation in the south of the Sichuan-Yunnan is dominated by expansion, and in the north is dominated by contraction. The north-south component strain rate shows that there is a significant positive high-value zone in and around the Xianshuihe fault zone, while southern Sichuan-Yunnan is a more significant negative-value zone, and the distribution of negative high-value zones is controlled by the south boundary of the Sichuan-Yunnan block. Based on the fault activity and focal mechanism data, the study area was divided into several seismic source zones. We translated the geodetic strain rates into rates of seismic moment release in each zone and compared them with earthquake catalog-based moment rates, to evaluate the potential of seismic activity of the region. The analysis shows the geodetic strain is completely released seismically for most of the study area. However, for the southern Yunnan，the geodesy-based moment rates are more than 2 times higher than the earthquake-based rates. This result indicates that at least a large earthquake may occur in southern Yunnan in the future.</p>

Flow, process forces and strains during Friction Stir Welding: A comprehensive First principle approach

2020 ◽  
pp. 095440542097008
Author(s):  
Dhruv Bajaj ◽  
Arshad Noor Siddiquee ◽  
Noor Zaman Khan ◽  
AK Mukhopadhyay ◽  
Sohail M A Khan Mohammed ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Shear Strain ◽  
Material Flow ◽  
Large Scale ◽  
Defect Formation ◽  
First Principle ◽  
Flow Process ◽  
Maximum Shear Strain ◽  
Friction Stir ◽  
Process Forces

Friction stir welding is recent yet spectacular process, which assumes accrescent expanse to evolve as a multi-purpose process. Its potential is greatly being tapped through large-scale experimental and computer simulation-based investigations. Several simulation and empirical models have been proposed but exact fundamental analyses on forces, material flow and strain are still absent. Complexities associated with the process are perhaps the main reason that a fundamental analysis is difficult. A comprehensive analysis of this kind is critical for understanding the evolution of microstructure, mechanical properties of joint and defect formation. This study presents an analysis of material flow, process forces and strains using first principle approach. Results have been presented as exact mathematical expressions in terms of material properties and process parameters. It was demonstrated that the material during stirring experiences direct and shear strains both when it moves from advancing side to retreating side in front of the tool and after rotation deposits behind the tool. It was also demonstrated that the strain significantly reduced from advancing to retreating side; for a typical case the shear strain greater than 10,000% prevails in advancing side and the maximum shear strain on retreating side is of the order of 6000%.

An Experimental Characterization of the Interaction Between Two Tandem Planar Jets in a Crossflow

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Kun Zhao ◽  
Patrick N. Okolo ◽  
Yong Wang ◽  
John Kennedy ◽  
Gareth J. Bennett
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Near Field ◽  
Mean Flow ◽  
Piv Measurement ◽  
Jet Trajectory ◽  
The Mean ◽  
Pod Analysis ◽  
Particle Imaging ◽  
Quantitative Definition

This study reports an experimental investigation of two planar jets in a crossflow in a tandem arrangement. Tests were conducted in an open-jet wind tunnel facility using two-dimensional (2D)-particle imaging velocimetry (PIV) measurement. Using the terminology in the dual jets in a quiescent ambient, the mean flow field of the crossflow arrangement was divided into a converging region, a merging region, and a combined region. An approach to determining the range of these three regions was proposed based on the mean characteristics of horizontal velocity profiles of the flow field, validated by the experimental data. The momentum-dominated near field (MDNF) for the rear jet in the dual-jet configuration was recognized using the horizontal offset of mean jet trajectory, which accordingly gives a quantitative definition of the MDNF range. Discussions were made on the effects of different parameters on the three regions and MDNF. Finally, snapshot proper orthogonal decomposition (POD) analysis was conducted, characterizing the coherent structures of the flow field, particularly the large-scale vortices. It was observed that the large-scale vortices mainly occur in the shear layers of the jets and their occurrence is affected by the parameters of the jets. In addition, compared with the single-jet configuration, the introduction of the front jet was found to contribute to the occurrence and development of the large-scale vortices.

scholarly journals Combining earthquakes and GPS data to estimate the probability of future earthquakes with magnitude <i>M</i><sub>w</sub> ≥ 6.0

2013 ◽  
Vol 1 (5) ◽  
pp. 5729-5752
Author(s):  
K.-P. Chen ◽  
Y.-B. Tsai ◽  
W.-Y. Chang
Keyword(s):  
Strain Rate ◽  
Shear Strain ◽  
High Probability ◽  
Likelihood Method ◽  
Gps Data ◽  
Shear Strain Rate ◽  
Maximum Shear Strain ◽  
B Values ◽  
Two Parameters ◽  
Benioff Strain

Abstract. According to Wyss et al. (2000) result indicates that future main earthquakes can be expected along zones characterized by low b values. In this study we combine Benioff strain with global positioning system (GPS) data to estimate the probability of future Mw ≥ 6.0 earthquakes for a grid covering Taiwan. An approach similar to the maximum likelihood method was used to estimate Gutenberg–Richter parameters a and b. The two parameters were then used to estimate the probability of simulating future earthquakes of Mw ≥ 6.0 for each of the 391 grids (grid interval = 0.1°) covering Taiwan. The method shows a high probability of earthquakes in western Taiwan along a zone that extends from Taichung southward to Nantou, Chiayi, Tainan and Kaohsiung. In eastern Taiwan, there also exists a high probability zone from Ilan southward to Hualian and Taitung. These zones are characterized by high earthquake entropy, high maximum shear strain rates, and paths of low b values. A relation between entropy and maximum shear strain rate is also obtained. It indicates that the maximum shear strain rate is about 4.0 times the entropy. The results of this study should be of interest to city planners, especially those concerned with earthquake preparedness. And providing the earthquake insurers to draw up the basic premium.

scholarly journals Crevasse initiation and history within the McMurdo Shear Zone, Antarctica

2019 ◽  
Vol 65 (254) ◽  
pp. 989-999 ◽  
Author(s):  
Lynn Kaluzienski ◽  
Peter Koons ◽  
Ellyn Enderlin ◽  
Gordon Hamilton ◽  
Zoe Courville ◽  
...  
Keyword(s):  
Strain Rate ◽  
Shear Strain ◽  
Shear Zone ◽  
Large Scale ◽  
Radar Data ◽  
Small Scale ◽  
Shear Strain Rate ◽  
Surface Shear ◽  
Study Region ◽  
In Situ Data

AbstractWhile large-scale observations of intensified fracture and rifting can be observed through remote-sensing observations, understanding crevasse initiation may best be achieved with small-scale observations in which crevasses can be directly observed. Here we investigate the kinematic drivers of crevasse initiation in the McMurdo Shear Zone (MSZ), Antarctica. We delineated 420 crevasses from ~95 km of 400 MHz frequency ground-penetrating radar data and compared these data with kinematic outputs derived from remotely-sensed ice surface velocities to develop a statistical method to estimate crevasse initiation threshold strain rate values. We found the MSZ to be dominated by simple shear and that surface shear strain rates proved best for predicting crevasse features, with regions of higher shear strain rate more likely to have a greater number of crevasses. In the surveyed portion of our study region, values of shear strain rate and vorticity rate derived from the MEaSUREs2 velocity dataset range between 0.005–0.020 and 0.006–0.022 a−1, respectively, with crevasses located at ≥0.011 and ≥0.013 a−1. While threshold values from this study cannot be directly applied to other glacial environments, the method described here should allow for the study of shear margin evolution and assessment of localized damage and weakening processes in other locations where in situ data are available.

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