scholarly journals Experimental Study on Diesel Spray Characteristics and Autoignition Process

2011 ◽  
Vol 2011 ◽  
pp. 1-20 ◽  
Author(s):  
Özgür Oğuz Taşkiran ◽  
Metin Ergeneman
Keyword(s):  
High Speed ◽  
Ignition Time ◽  
Cetane Number ◽  
Ccd Camera ◽  
Nozzle Geometry ◽  
Diesel Spray ◽  
Macroscopic Properties ◽  
Constant Volume Combustion Chamber ◽  
Nozzle Geometries ◽  
Ignition Characteristics

The main goal of this study is to get the temporal and spatial spray evolution under diesel-like conditions and to investigate autoignition process of sprays which are injected from different nozzle geometries. A constant volume combustion chamber was manufactured and heated internally up to 825 K at 3.5 MPa for experiments. Macroscopic properties of diesel spray were recorded via a high-speed CCD camera by using shadowgraphy technique, and the images were analyzed by using a digital image processing program. To investigate the influence of nozzle geometry, 4 different types of divergent, straight, straight-rounded, convergent-rounded nozzles, were manufactured and used in both spray evolution and autoignition experiments. The internal geometry of the injector nozzles were obtained by using silicone mold method. The macroscopic properties of the nozzles are presented in the study. Ignition behaviour of different nozzle types was observed in terms of ignition delay time and ignition location. A commercial Diesel fuel,n-heptane, and a mixture of hexadecane-heptamethylnonane (CN65—cetane number 65) were used as fuels at ignition experiments. The similar macroscopic properties of different nozzles were searched for observing ignition time and ignition location differences. Though spray and ignition characteristics revealed very similar results, the dissimilarities are presented in the study.

Nozzle Spraying Model of Combustion Thermal Spray

2013 ◽  
Vol 655-657 ◽  
pp. 211-217 ◽  
Author(s):  
Wen Liang Guo ◽  
Zheng Guo
Keyword(s):  
Turbulent Flows ◽  
High Speed ◽  
Numerical Solutions ◽  
Substrate Surface ◽  
Ccd Camera ◽  
Nozzle Geometry ◽  
Flame Spraying ◽  
Free Jet ◽  
Powder Particles ◽  
Mixing Length Theory

The flame used in combustion flame spraying is typical of a high-temperature free jet. The flow fields of free jets are multi-phase flows that couple the mass and heat transfer. The analytical and numerical solutions to turbulent flows are engineering approximations. This work uses Prandtle’s mixing-length theory to describe the flame spreading of free combustion spray jet and uses nozzle spray model to describe the distribution of the powder particles sprayed from powder nozzle to the substrate surface. The nozzle geometry and the parameters determine the distribution of the powder particles. The nozzle spray model has the same physical meaning with the jet spreading angle. Experimental measurements were carried by a high-speed CCD camera.

Spray Tip Penetration of Inversed-delta Injection Rate Shaping in Non-Vapourising Condition

2019 ◽  
Vol 16 (3) ◽  
pp. 7048-7060
Author(s):  
M. F. E. Abdullah ◽  
Y. Toyama ◽  
S. Saruwatari ◽  
S. Akiyama ◽  
T. Shimada ◽  
...  
Keyword(s):  
High Speed ◽  
Injection Pressure ◽  
Injection Rate ◽  
Diesel Spray ◽  
Spray Tip Penetration ◽  
Mems Sensor ◽  
Fuel Delivery ◽  
Rate Shaping ◽  
Constant Volume Combustion Chamber ◽  
Performance And Emissions

The performance and emissions of diesel engine are highly depending on the fuel delivery process thus, injection rate shaping approach is expected to be crucial in the development of a highly efficient and clean modern engine. A novel rate shaping injector called TAIZAC (TAndem Injection Zapping ACtivation) is used to realise an injection rate shaping of progressive ramp-down of high initial injection pressure as in inversed-delta shape. This study aims to investigate diesel spray tip penetration behaviour in inverseddelta injection rate shaping. The experiments are conducted under a high-density nonvapourising condition in a constant volume combustion chamber. High-speed diffused back illumination DBI imaging of the diesel spray is acquired at 30,000 fps using mercury lamp as the light source. The tip penetration of the inversed-delta injection is smaller than that of rectangle injection regardless of their injection momentum which is proportional to t0.5 and t0.43 in rectangle and inversed-delta injection case, respectively. To examine the potential of inversed-delta injection on wall heat loss reduction, diesel spray flame impinges to a MEMS sensor located at 28-mm downstream. It is interesting to note that the heat flux in 200 MPa inversed-delta injection is reduced by approximately 15% compared to 200 MPa rectangle injection even though their tip penetration starts to diverge at approximately 30 mm; indicates the TAIZAC injector potential in improving engine thermal efficiency.

Acetylene Ignition Process in Combustion Thermal Spray

2013 ◽  
Vol 376 ◽  
pp. 65-68
Author(s):  
Wen Liang Guo ◽  
Zheng Guo
Keyword(s):  
Thermal Spray ◽  
Time Scale ◽  
High Speed ◽  
Critical Radius ◽  
Ignition Time ◽  
Minimum Energy ◽  
Ccd Camera ◽  
Ignition Process ◽  
Free Jet ◽  
Fuel Jet

The acetylene ignition process in combustion thermal spray is typical of a laminar diffusion jet. It has all the features of a free jet. The aim of this research is to obtain the detail sparking ignition evolution process and the chemical reaction time scale and calculate the critical radius and minimum energy input required to produce a self-propagating flame in an acetylene fuel jet. Experiments are carried out by using a unique high-speed continuous CCD camera. The results show that the full sparking ignition time needs about 8 ms and this time scale can be used in the calculation of the flame flow fields in the combustion thermal spray jet.

scholarly journals Modelling of cavitation in diesel injector nozzles

2008 ◽  
Vol 616 ◽  
pp. 153-193 ◽  
Author(s):  
E. GIANNADAKIS ◽  
M. GAVAISES ◽  
C. ARCOUMANIS
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Volume Fraction ◽  
Ccd Camera ◽  
Nozzle Geometry ◽  
Liquid Volume ◽  
Liquid Volume Fraction ◽  
Validation Data ◽  
Real Size ◽  
A Charge

A computational fluid dynamics cavitation model based on the Eulerian–Lagrangian approach and suitable for hole-type diesel injector nozzles is presented and discussed. The model accounts for a number of primary physical processes pertinent to cavitation bubbles, which are integrated into the stochastic framework of the model. Its predictive capability has been assessed through comparison of the calculated onset and development of cavitation inside diesel nozzle holes against experimental data obtained in real-size and enlarged models of single- and multi-hole nozzles. For the real-size nozzle geometry, high-speed cavitation images obtained under realistic injection pressures are compared against model predictions, whereas for the large-scale nozzle, validation data include images from a charge-coupled device (CCD) camera, computed tomography (CT) measurements of the liquid volume fraction and laser Doppler velocimetry (LDV) measurements of the liquid mean and root mean square (r.m.s.) velocities at different cavitation numbers (CN) and two needle lifts, corresponding to different cavitation regimes inside the injection hole. Overall, and on the basis of this validation exercise, it can be argued that cavitation modelling has reached a stage of maturity, where it can usefully identify many of the cavitation structures present in internal nozzle flows and their dependence on nozzle design and flow conditions.

High-speed brightfield 3-D imaging and 3-D image analysis of thick and overlapped cell clusters in cytological preparations

1994 ◽  
Vol 52 ◽  
pp. 218-219
Author(s):  
Robert W. Mackin
Keyword(s):  
Image Analysis ◽  
High Speed ◽  
Three Dimensional ◽  
Image Data ◽  
Ccd Camera ◽  
Objective Lens ◽  
Array Processor ◽  
Vaginal Smears ◽  
Low Contrast ◽  
Computer Controlled

This paper presents two advances towards the automated three-dimensional (3-D) analysis of thick and heavily-overlapped regions in cytological preparations such as cervical/vaginal smears. First, a high speed 3-D brightfield microscope has been developed, allowing the acquisition of image data at speeds approaching 30 optical slices per second. Second, algorithms have been developed to detect and segment nuclei in spite of the extremely high image variability and low contrast typical of such regions. The analysis of such regions is inherently a 3-D problem that cannot be solved reliably with conventional 2-D imaging and image analysis methods.High-Speed 3-D imaging of the specimen is accomplished by moving the specimen axially relative to the objective lens of a standard microscope (Zeiss) at a speed of 30 steps per second, where the stepsize is adjustable from 0.2 - 5μm. The specimen is mounted on a computer-controlled, piezoelectric microstage (Burleigh PZS-100, 68/μm displacement). At each step, an optical slice is acquired using a CCD camera (SONY XC-11/71 IP, Dalsa CA-D1-0256, and CA-D2-0512 have been used) connected to a 4-node array processor system based on the Intel i860 chip.

Five-Dimensional Microscopy using Widefield-Deconvolution: Practical Considerations and Biological Applications

1996 ◽  
Vol 54 ◽  
pp. 268-269
Author(s):  
W.F. Marshall ◽  
K. Oegema ◽  
J. Nunnari ◽  
A.F. Straight ◽  
D.A. Agard ◽  
...  
Keyword(s):  
Confocal Microscopy ◽  
High Speed ◽  
Laser Scanning ◽  
Ccd Camera ◽  
Image Plane ◽  
Time Lapse ◽  
Laser Scanning Confocal Microscopy ◽  
Three Dimensions ◽  
Excitation Light ◽  
Cooled Ccd

The ability to image cells in three dimensions has brought about a revolution in biological microscopy, enabling many questions to be asked which would be inaccessible without this capability. There are currently two major methods of three dimensional microscopy: laser-scanning confocal microscopy and widefield-deconvolution microscopy. The method of widefield-deconvolution uses a cooled CCD to acquire images from a standard widefield microscope, and then computationally removes out of focus blur. Using such a scheme, it is easy to acquire time-lapse 3D images of living cells without killing them, and to do so for multiple wavelengths (using computer-controlled filter wheels). Thus, it is now not only feasible, but routine, to perform five dimensional microscopy (three spatial dimensions, plus time, plus wavelength).Widefield-deconvolution has several advantages over confocal microscopy. The two main advantages are high speed of acquisition (because there is no scanning, a single optical section is acquired at a time by using a cooled CCD camera) and the use of low excitation light levels Excitation intensity can be much lower than in a confocal microscope for three reasons: 1) longer exposures can be taken since the entire 512x512 image plane is acquired in parallel, so that dwell time is not an issue, 2) the higher quantum efficiently of a CCD detect over those typically used in confocal microscopy (although this is expected to change due to advances in confocal detector technology), and 3) because no pinhole is used to reject light, a much larger fraction of the emitted light is collected. Thus we can typically acquire images with thousands of photons per pixel using a mercury lamp, instead of a laser, for illumination. The use of low excitation light is critical for living samples, and also reduces bleaching. The high speed of widefield microscopy is also essential for time-lapse 3D microscopy, since one must acquire images quickly enough to resolve interesting events.

Towards A Multi-FPGA Infrared Simulator

2007 ◽  
Vol 4 (4) ◽  
pp. 343-355 ◽  
Author(s):  
Vinay Sriram ◽  
David Kearney
Keyword(s):  
Homeland Security ◽  
Reconfigurable Computing ◽  
High Speed ◽  
High Performance ◽  
Large Scale ◽  
Computation Time ◽  
Ccd Camera ◽  
Hardware Acceleration ◽  
Limiting Factor ◽  
Scene Simulation

High speed infrared (IR) scene simulation is used extensively in defense and homeland security to test sensitivity of IR cameras and accuracy of IR threat detection and tracking algorithms used commonly in IR missile approach warning systems (MAWS). A typical MAWS requires an input scene rate of over 100 scenes/second. Infrared scene simulations typically take 32 minutes to simulate a single IR scene that accounts for effects of atmospheric turbulence, refraction, optical blurring and charge-coupled device (CCD) camera electronic noise on a Pentium 4 (2.8GHz) dual core processor [7]. Thus, in IR scene simulation, the processing power of modern computers is a limiting factor. In this paper we report our research to accelerate IR scene simulation using high performance reconfigurable computing. We constructed a multi Field Programmable Gate Array (FPGA) hardware acceleration platform and accelerated a key computationally intensive IR algorithm over the hardware acceleration platform. We were successful in reducing the computation time of IR scene simulation by over 36%. This research acts as a unique case study for accelerating large scale defense simulations using a high performance multi-FPGA reconfigurable computer.

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