PIV Measurements of In-Cylinder Flow in a Four-Stroke Utility Engine and Correlation With Combustion Measurements

2004 ◽  
Author(s):  
Karen E. Bevan ◽  
Jaal B. Ghandhi
Keyword(s):  
Kinetic Energy ◽  
Horizontal Plane ◽  
Large Scale ◽  
Vertical Plane ◽  
Combustion Performance ◽  
Flow Parameters ◽  
Combustion Duration ◽  
Measurement Plane ◽  
Cylinder Flow ◽  
High Pass

Large-scale flows in internal combustion engines directly affect combustion duration and emissions production. The effect of intake port geometry on combustion performance was studied in a four-stroke spark-ignition utility engine. Three intake port geometries were investigated at three port orientations. In-cylinder flows in orthogonal planes were measured using particle image velocimetry (PIV). Combustion performance data were acquired at two load conditions and three equivalence ratios. The PIV data were processed to calculate the large-scale mean vorticity and mean high-pass filtered velocity. These flow parameters were used to characterize the in-cylinder flow in a measurement plane in a physically meaningful way and correlate the flow with combustion performance. The cumulative distribution functions of the flow parameters did not show significant port-to-port differences in either measurement plane. The mean vorticity and high-pass filtered velocity did exhibit differences due to port orientation in the horizontal plane, but not in the vertical plane. The 0-degree ports consistently produced the highest values of large-scale mean vorticity and mean high-pass filtered velocity in the horizontal plane. The kinetic energy present at ignition was also calculated to characterize the flow. The ensemble average values of the mean large-scale vorticity, high-pass filtered velocity and kinetic energy were compared to the combustion duration. The vertical plane vorticity and high-pass filtered velocity did not correlate with combustion performance. The horizontal plane vorticity and high-pass filtered velocity were found to exhibit modest correlation at the fixed torque condition, and somewhat lower correlation at the WOT condition. The correlation between kinetic energy and combustion duration was poor. The best correlation of flow field structure with engine performance was achieved for ports at the 0-degree port orientation. Ports at this orientation generated coherent, large-scale swirl.

Particle Image Velocimetry Measurements of In-Cylinder Flow in a Four-Stroke Utility Engine and Correlation With Combustion Measurements

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Karen E. Bevan ◽  
Jaal B. Ghandhi
Keyword(s):  
Kinetic Energy ◽  
Horizontal Plane ◽  
Large Scale ◽  
Particle Image ◽  
Vertical Plane ◽  
Combustion Performance ◽  
Combustion Duration ◽  
Image Velocimetry ◽  
The Mean ◽  
High Pass

Large-scale flows in internal combustion engines directly affect combustion duration and emission production. The effect of intake port geometry on combustion performance was studied in a four-stroke spark-ignition utility engine. Three intake port geometries were investigated at three port orientations. In-cylinder flows in orthogonal planes were measured using particle image velocimetry (PIV). The PIV data were processed to calculate the large-scale mean vorticity and mean high-pass filtered velocity. Combustion performance data were separately acquired at two load conditions at a fixed equivalence ratio, and compared with the PIV data. The cumulative distribution functions of the flow parameters did not show significant port-to-port differences in either measurement plane. The mean vorticity and high-pass filtered velocity did exhibit differences due to port orientation in the horizontal plane, but not in the vertical plane. The 0 deg ports (tangential orientation) consistently produced the highest values of large-scale mean vorticity and mean high-pass filtered velocity in the horizontal plane. The kinetic energy present at ignition was also calculated to characterize the flow. The ensemble-averaged values of the mean large-scale vorticity, high-pass filtered velocity, and kinetic energy were compared to the combustion duration. The vertical-plane vorticity and high-pass filtered velocity did not correlate with combustion performance. The horizontal-plane vorticity and high-pass filtered velocity were found to exhibit modest correlation at the fixed torque condition, and somewhat lower correlation at the wide open throttle condition. The correlation between kinetic energy and combustion duration was poor. The best correlation of flow field structure with engine performance was achieved for ports at the 0 deg port orientation. Ports at this orientation generated coherent, large-scale swirl.

Coherent Structures in Shallow Water Jets

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
A.-M. Shinneeb ◽  
J. D. Bugg ◽  
R. Balachandar
Keyword(s):  
Coherent Structures ◽  
Horizontal Plane ◽  
Large Scale ◽  
Solid Wall ◽  
Vertical Wall ◽  
Vertical Plane ◽  
Vertical Direction ◽  
Particle Image Velocimetry System ◽  
Identification Algorithm ◽  
Vortical Structures

This paper reports an experimental investigation of a round jet discharging horizontally from a vertical wall into an isothermal body of water confined in the vertical direction by a flat wall on the bottom and a free surface on top. Specifically, this paper focuses on the effects of vertical confinement on the characteristics of large vortical structures. The jet exit velocity was 2.5 m/s, and the exit Reynolds number was 22,500. Experiments were performed at water layer depths corresponding to 15, 10, and 5 times the jet exit diameter (9 mm). The large-scale structures were exposed by performing a proper orthogonal decomposition (POD) analysis of the velocity field obtained using a particle image velocimetry system. Measurements were made on vertical and horizontal planes—both containing the axis of the jet. All fields-of-view were positioned at an axial location in the range 10<x/D<80. The number of modes used for the POD reconstruction of the velocity fields was selected to recover ∼40% of the turbulent kinetic energy. A vortex identification algorithm was then employed to quantify the size, circulation, and direction of rotation of the exposed vortices. A statistical analysis of the distribution of number, size, and strength of the identified vortices was carried out to explore the characteristics of the coherent structures. The results clearly reveal the existence of numerous vortical structures of both rotational senses in the jet flow, and their number generally decreases in the axial direction while their size increases. The size of vortices identified in the vertical plane is restricted by the water depth, while they are allowed to increase in size in the horizontal plane. Moreover, the results show a significant decrease in the number of small vortices for the shallowest case in the horizontal plane, with a corresponding increase in the number of large vortices and a significant increase in their size. This behavior was accompanied with an increase in the vortex circulation in the horizontal plane and a reduction in the circulation in the vertical plane. This is indicative of the dominance of the pairing process due to shallowness. Moreover, the balance between the positive and negative vortices in the vertical plane changed because of the formation of negative (clockwise) vortices near the solid wall at downstream locations.

scholarly journals The Relationship between In-Cylinder Flow-Field near Spark Plug Areas, the Spark Behavior, and the Combustion Performance inside an Optical S.I. Engine

2019 ◽  
Vol 9 (8) ◽  
pp. 1545 ◽  
Author(s):  
Atsushi Nishiyama ◽  
Minh Khoi Le ◽  
Takashi Furui ◽  
Yuji Ikeda
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Entire Area ◽  
Combustion Performance ◽  
Simultaneous Imaging ◽  
Spark Plug ◽  
Combustion Duration ◽  
Image Velocimetry ◽  
Flame Development ◽  
Cylinder Flow

The stringent regulations that were placed on gasoline vehicles demand significant improvement of the powertrain unit, not only to become cleaner but also more efficient. Therefore, there is a strong need to understand the complex in-cylinder processes that will have a direct effect on the combustion quality. This study applied multiple high-speed optical imaging to investigate the interaction between the in-cylinder flow, the spark, the flame, and combustion performance. These individual elements have been studied closely in the literature but the combined effect is not well understood. Simultaneous imaging of in-cylinder flow and flame tomography using high-speed Particle Image Velocimetry (PIV), as well as simultaneous high-speed spark imaging, were applied to port-injected optical gasoline imaging. The captured images were processed using in-house MATLAB algorithms and the deduced data shows a trend that higher in-cylinder flow velocity near the spark will increase the stretch distance of the spark and decrease the ignition delay. However, these do not have much effect on the combustion duration, and it is the flow-field in the entire area surrounding the flame development that will influence how fast the combustion and flame growth will occur.

scholarly journals Dielectric anisotropy as indicator of crystal orientation fabric in Dome Fuji ice core: method and initial results

2021 ◽  
pp. 1-12
Author(s):  
Tomotaka Saruya ◽  
Shuji Fujita ◽  
Ryo Inoue
Keyword(s):  
Crystal Orientation ◽  
Horizontal Plane ◽  
Ice Core ◽  
Vertical Plane ◽  
Vertical Direction ◽  
Core Sample ◽  
Dielectric Anisotropy ◽  
Principal Axes ◽  
Polycrystalline Ice ◽  
Initial Results

Abstract Polycrystalline ice is known to exhibit macroscopic anisotropy in relative permittivity (ɛ) depending on the crystal orientation fabric (COF). Using a new system designed to measure the tensorial components of ɛ, we investigated the dielectric anisotropy (Δɛ) of a deep ice core sample obtained from Dome Fuji, East Antarctica. This technique permits the continuous nondestructive assessment of the COF in thick ice sections. Measurements of vertical prism sections along the core showed that the Δɛ values in the vertical direction increased with increasing depth, supporting previous findings of c-axis clustering around the vertical direction. Analyses of horizontal disk sections demonstrated that the magnitude of Δɛ in the horizontal plane was 10–15% of that in the vertical plane. In addition, the directions of the principal axes of tensorial ɛ in the horizontal plane corresponded to the long or short axis of the elliptically elongated single-pole maximum COF. The data confirmed that Δɛ in the vertical and horizontal planes adequately indicated the preferred orientations of the c-axes, and that Δɛ can be considered to represent a direct substitute for the normalized COF eigenvalues. This new method could be extremely useful as a means of investigating continuous and depth-dependent variations in COF.

scholarly journals The SINFONI survey of powerful radio galaxies at z ~ 2: Jet-driven AGN feedback during the Quasar Era

2017 ◽  
Vol 599 ◽  
pp. A123 ◽  
Author(s):  
N. P. H. Nesvadba ◽  
C. De Breuck ◽  
M. D. Lehnert ◽  
P. N. Best ◽  
C. Collet
Keyword(s):  
Kinetic Energy ◽  
Interstellar Medium ◽  
Large Scale ◽  
High Redshift ◽  
Radio Galaxies ◽  
Energy Output ◽  
Host Galaxy ◽  
Powerful Radio ◽  
Massive Galaxies ◽  
Gas Kinematics

We present VLT/SINFONI imaging spectroscopy of the rest-frame optical emission lines of warm ionized gas in 33 powerful radio galaxies at redshifts z ≳ 2, which are excellent sites to study the interplay of rapidly accreting active galactic nuclei and the interstellar medium of the host galaxy in the very late formation stages of massive galaxies. Our targets span two orders of magnitude in radio size (2−400 kpc) and kinetic jet energy (a few 1046– almost 1048 erg s-1). All sources have complex gas kinematics with broad line widths up to ~1300 km s-1. About half have bipolar velocity fields with offsets up to 1500 km s-1 and are consistent with global back-to-back outflows. The others have complex velocity distributions, often with multiple abrupt velocity jumps far from the nucleus of the galaxy, and are not associated with a major merger in any obvious way. We present several empirical constraints that show why gas kinematics and radio jets seem to be physically related in all galaxies of the sample. The kinetic energy in the gas from large scale bulk and local outflow or turbulent motion corresponds to a few 10-3 to 10-2 of the kinetic energy output of the radio jet. In galaxies with radio jet power ≳ 1047 erg s-1, the kinetic energy in global back-to-back outflows dominates the total energy budget of the gas, suggesting that bulk motion of outflowing gas encompasses the global interstellar medium. This might be facilitated by the strong gas turbulence, as suggested by recent analytical work. We compare our findings with recent hydrodynamic simulations, and discuss the potential consequences for the subsequent evolution of massive galaxies at high redshift. Compared with recent models of metal enrichment in high-z AGN hosts, we find that the gas-phase metallicities in our galaxies are lower than in most low-z AGN, but nonetheless solar or even super-solar, suggesting that the ISM we see in these galaxies is very similar to the gas from which massive low-redshift galaxies formed most of their stars. This further highlights that we are seeing these galaxies near the end of their active formation phase.

scholarly journals A New Method for the Calculation of Energy and Power Requirements of Bucket Wheel Excavators

2019 ◽  
Vol 10 (1) ◽  
pp. 15-20
Author(s):  
József András ◽  
József Kovács ◽  
Endre András ◽  
Ildikó Kertész ◽  
Ovidiu Bogdan Tomus
Keyword(s):  
Energy Consumption ◽  
Numerical Method ◽  
Horizontal Plane ◽  
Vertical Plane ◽  
New Method ◽  
Energy Requirements ◽  
Belt Conveyor ◽  
Analytical Formulas ◽  
Power And Energy ◽  
Continuous Working

Abstract The bucket wheel excavator (BWE) is a continuous working rock harvesting device which removes the rock by means of buckets armoured with teeth, mounted on the wheel and which transfers rock on a main hauling system (generally a belt conveyor). The wheel rotates in a vertical plane and swings in the horizontal plane and raised / descended in the vertical plane by a boom. In this paper we propose a graphical-numerical method in order to calculate the power and energy requirements of the main harvesting structure (the bucket wheel) of the BWE. This approach - based on virtual models of the main working units of bucket wheel excavators and their working processes - is more convenient than those based on analytical formulas and simplification hypotheses, and leads to improved operation, reduced energy consumption, increased productivity and optimal use of available actuating power.

scholarly journals Estimation of rainfall erosivity based on WRF-derived raindrop size distributions

2020 ◽  
Vol 24 (11) ◽  
pp. 5407-5422
Author(s):  
Qiang Dai ◽  
Jingxuan Zhu ◽  
Shuliang Zhang ◽  
Shaonan Zhu ◽  
Dawei Han ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Kinetic Energy ◽  
Water Conservation ◽  
Large Scale ◽  
Weather Prediction ◽  
Wrf Model ◽  
Analysis Data ◽  
Rainfall Erosivity ◽  
Size Distributions ◽  
Raindrop Size

Abstract. Soil erosion can cause various ecological problems, such as land degradation, soil fertility loss, and river siltation. Rainfall is the primary water-driven force for soil erosion, and its potential effect on soil erosion is reflected by rainfall erosivity that relates to the raindrop kinetic energy. As it is difficult to observe large-scale dynamic characteristics of raindrops, all the current rainfall erosivity models use the function based on rainfall amount to represent the raindrops' kinetic energy. With the development of global atmospheric re-analysis data, numerical weather prediction techniques become a promising way to estimate rainfall kinetic energy directly at regional and global scales with high spatial and temporal resolutions. This study proposed a novel method for large-scale and long-term rainfall erosivity investigations based on the Weather Research and Forecasting (WRF) model, avoiding errors caused by inappropriate rainfall–energy relationships and large-scale interpolation. We adopted three microphysical parameterizations schemes (Morrison, WDM6, and Thompson aerosol-aware) to obtain raindrop size distributions, rainfall kinetic energy, and rainfall erosivity, with validation by two disdrometers and 304 rain gauges around the United Kingdom. Among the three WRF schemes, Thompson aerosol-aware had the best performance compared with the disdrometers at a monthly scale. The results revealed that high rainfall erosivity occurred in the west coast area at the whole country scale during 2013–2017. The proposed methodology makes a significant contribution to improving large-scale soil erosion estimation and for better understanding microphysical rainfall–soil interactions to support the rational formulation of soil and water conservation planning.

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