Penetration Angle Research Articles

Experimental investigation of effects of super high injection pressure on diesel spray and induced shock waves characteristics

Modern diesel engines employ higher injection pressure in the common-rail injection system that utilizes high-speed fuel jet to achieve rapid fuel-air mixing for spray atomization improvement. However, the spray characteristics under super high pressure are not well understood. To provide more information on spray characteristics, both the macro- and micro-characteristics of spray have been investigated under super high pressures (up to 300MPa) via an experimental method. The spray penetration and spray cone angle were measured using a high speed camera and the microscopic characteristic of Sauter mean diameter (SMD) was obtained via Malvern Spray Tec to analyze the influence of super high injection pressure on diesel spray atomization. Induced shock waves were captured using a Schlieren system when the spray tip velocity was greater than the local sound velocity accompanied by diesel spray. The results obtained show that higher injection pressures lead to larger spray velocities and a smaller shock wave angle if it exists, with connection between spray and shock waves, and generates a smaller SMD with less decreasing amplitude. Additionally, two different types of leading shock waves—bow and oblique shock wave appeared sequentially with increasing injection pressure.

Preliminary Study for Designing a Novel Vein-Visualizing Device.

Venipuncture is an important health diagnosis process. Although venipuncture is one of the most commonly performed procedures in medical environments, locating the veins of infants, obese, anemic, or colored patients is still an arduous task even for skilled practitioners. To solve this problem, several devices using infrared light have recently become commercially available. However, such devices for venipuncture share a common drawback, especially when visualizing deep veins or veins of a thick part of the body like the cubital fossa. This paper proposes a new vein-visualizing device applying a new penetration method using near-infrared (NIR) light. The light module is attached directly on to the declared area of the skin. Then, NIR beam is rayed from two sides of the light module to the vein with a specific angle. This gives a penetration effect. In addition, through an image processing procedure, the vein structure is enhanced to show it more accurately. Through a phantom study, the most effective penetration angle of the NIR module is decided. Additionally, the feasibility of the device is verified through experiments in vivo. The prototype allows us to visualize the vein patterns of thicker body parts, such as arms.

Effects of Drill Geometry and Penetration Angle on Temperature and Holes Surfaces for Cortical Bovine Bone: An in Vitro Study

Drilling of bone is the most important part of the internal and external fixation processes in orthopaedic surgery. This surgical procedure usually is performed manually with a hand-held tool and is greatly dependent on the surgeon skill. Imprecise manipulation of the hand-held tool can cause the drill skidding across the bone surface and leads to a localized increase in temperature resulting a thermal necrosis on the soft tissue surrounding the hole surface. The magnitudes of the friction energy are greatly dependent with the drill geometry design and the penetration angle. For the sake of importance on studying this phenomenon, this paper aim to investigate the effects of drill geometry on temperatures rise and hole surface in bone drilling procedure. Totals of 17 drills were designed and tested with different geometry namely point angle, helix angle and web thickness on different penetration angle (00, 150, and 300) to mimic the manually control penetration by the surgeon. From the conducted investigation, the most significant parameter that affects the temperature rise and holes surface quality was the penetration angle followed by the point angle. In addition, the interaction between helix angle and web thickness also controlled the drilling temperature and the performance of the hole surface.

Investigation of internal nozzle flow, spray and combustion characteristics fueled with diesel, gasoline and wide distillation fuel (WDF) based on a piezoelectric injector and a direct injection compression ignition engine

In this work, the internal nozzle flow, spray, combustion and emission characteristics of traditional diesel, gasoline and two kinds of WDF (gasoline/diesel blend fuel and kerosene) were comprehensively and systematically investigated based on a piezoelectric injector and a direct injection compression ignition engine. In fuel spray study, the behaviours of piezoelectric and solenoid injectors were compared. The macroscopic characteristics of test fuels including spray penetration, spray velocity and spray angle were investigated. A so-called “full cavitation model” was used for internal nozzle flow and cavitation simulation, wherein the characteristics such as turbulent kinetic energy and injection velocity are investigated. The simulation results of fuel internal nozzle flow are convincing to explain the experimental results of spray. In the combustion and emissions study, the KH-RT model which takes into account the cavitation and turbulence was used for spray prediction. KIVA4 and CHEMKIN codes are coupled to solve the chemical reaction. Two chemical reaction models, which have been developed by authors’ group in previous study, were used for investigating two combustion strategies, i.e., partially premixed combustion (PPC) and highly premixed combustion (HPC) fueled with traditional diesel, gasoline and two kinds of WDF. From the results, it can be inferred that, compared with diesel and gasoline, WDF is more suitable for utilization in compression ignition engines at present stage.

Applying Different Strategies within OpenFOAM to Investigate the Effects of Breakup and Collision Model on the Spray and in-Cylinder Gas Mixture Attribute

In the current study, a 3-D numerical simulation of two-phase flow has been conducted in a direct injection CI engine using the Eularian-Lagrangian approach and a new breakup model. The newly modified breakup scheme has been implemented for simulating the ultra-high pressure diesel injection. The effects of droplet breakup and collision model on the spray and in-cylinder gas characteristics have been examined using the open source code OpenFOAM. Spray penetration and cone angle are investigated as spray properties and surrounding gas motion are studied by in-cylinder gas velocity and pressure distribution for non-evaporating conditions. In addition, vapor penetration of the evaporating spray is presented to study the effects of current scheme on the evaporating condition. The continuous field is described by RANS equations and dynamics of the dispersed droplet is modeled by Lagrangian tracking scheme. Results of the proposed modified KHRT model are compared against other default methods in OpenFOAM and favorable agreement is achieved. Robustness and accuracy of different breakup schemes and collision models are also verified using the published experimental data. It is demonstrated that the proposed breakup scheme and Nordin collision model display very accurate results in the case of ultra-high pressure injection.

Laboratory measurements of a phase shift in the reflection from a water-mud interface due to water column variability

Harbor basins and certain continental shelf environments experience significant variability due to tides, surface heating, currents, and other oceanographic processes. Dynamic processes such as these can cause substantial sound speed and density fluctuations in the water column over short time periods, which are often unknown to sonar users. Such variations are not critical over high-velocity bottoms such as sand, but can produce significant changes in how sound interacts with low-velocity fine-grained sediments. High levels of variability and a low-velocity bottom, such as mud, can therefore present challenges in applications including mine detection, port protection and shallow water sonar. At certain penetration angles, temporal variations in the water-to-sediment sound speed ratio can cause 180 degree phase shifts in the reflected field, which in turn produces waveguide propagation and target scattering field variability. To begin to understand these processes, laboratory measurements of plane wave reflection were obtained from a water-mud interface while varying salinity and temperature of the water. Results indicate that the dynamic nature of sound speed ratio at the ocean bottom can cause significant effects in shallow water environments with muddy bottoms. [Work supported by ONR.]

Experimental study on spray, combustion and emission characteristics of pine oil/diesel blends in a multi-cylinder diesel engine

Pine oil has a high calorific value, which makes it an appropriate biofuel for diesel engines. In this paper, spray characteristics such as spray morphology, spray penetration and spray cone angle of pine oil-diesel blends were investigated under various injection pressures using a constant volume spray chamber. The effects of the injection pressure on the combustion and emission characteristics of pine oil-diesel blends were experimentally investigated in a four-cylinder diesel engine under medium EGR (24.6%). Four different fuels including pure diesel (P0), three blends of pine oil and diesel fuel denoted as P20 (20% pine oil and 80% diesel in volume), P40 (40% pine oil and 60% diesel in volume), and P50 (50% pine oil and 50% diesel in volume) were tested. Our results indicate that, as the injection pressure increases, the spray penetration of blended fuels increase, while the spray cone angle shows slightly change. And with the increasing of injection pressure, the peak values of heat release rate and in-cylinder pressure during the combustion of the four blended fuels increase, the BSFC slightly increase, the emissions of soot, CO and THC decrease, however NOx emissions increase. The effects of the increase of injection pressure on soot emissions of pure diesel are greater than that of blended fuels. When the mixing ratio of pine oil exceeds 40%, the beneficial effects of injection pressure on soot emissions from the combustion of blended fuels are weakened. At the same injection pressure, the BSFC of P20 almost equals the value of P0. As the mixing ratio of pine oil increases, the spray penetration and the spray cone angle of blended fuels increase, which enhanced the atomization process and fuel evaporation. With the increase ratio of pine oil, the peak values of in-cylinder pressure and heat release rate increase, the emissions of NOx, CO and THC increase and soot emissions decrease dramatically. For the combustion of the tested fuels, the number concentration and mass concentration of total PMs can be reduced by increasing the injection pressure or the amount of pine oil in the blends. At an injection pressure of 100MPa, the total PM number concentration and mass concentration of P50 are respectively lower 86.30% and 96.55% than the values for pure diesel.

Effect of organic montmorillonite on microstructure and properties of the OMMT/EVA/Asphalt composites

In order to improve the aging resistance and rutting resistance of the asphalt, a novel OMMT/EVA/asphalt composite was prepared by using organic montmorillonite (OMMT) and ethylene vinyl acetate (EVA) as modifiers via melt blending method. The microstructure and morphology of the EVA/asphalt composites and the OMMT/EVA/asphalt composites were characterized by X‐ray diffraction (XRD) and fluorescence microscopy (FM), respectively. XRD patterns indicate that the layers of OMMT are peeled off, and an exfoliated structure is formed. FM images show that a network structure appears between EVA and asphalt. The properties of the OMMT/EVA/asphalt composites were investigated by storage stability test, rotating thin film oven test (RTFOT), and dynamic shear rheometer (DSR), respectively. The results show that OMMT/EVA/asphalt composites exhibit better storage stability and aging resistance than that of EVA‐modified asphalt. Moreover, the obtained composites also show an increase in softening point and complex modulus (G*), and a decrease in penetration and phase angle (δ), which indicate that the OMMT/EVA/asphalt composites display good rutting resistance, high elasticity, and superior anti‐cracking properties. POLYM. COMPOS., 39:1959–1966, 2018. © 2016 Society of Plastics Engineers

Arc characteristics and metal transfer behavior of CMT + P welding process

The cold metal transfer (CMT) with addition of pulses (CMT+P) process is a new CMT welding method. The CMT+P transfer mode is a combination of a projected transfer mode with one droplet per pulse and a short circuit transfer mode during the cold metal transfer period. The results indicate that the current and voltage waveforms of the CMT+P welding process were quite different from those of the traditional CMT process. The appearance of the high initial arcing current and the current pulse steps as well as the low current for the pulse time phase for the first CMT period indicate a stable, smooth CMT+P transfer process. The high pulse current of the CMT+P process results in a higher heat input compared to the CMT process. A greater penetration and contact angle of the weld bead can be obtained by increasing the pulse number.

Study of liquid and vapor phase behavior on Diesel sprays for heavy duty engine nozzles

A lot of effort has been put in the past years into the understanding of the delivery and development of diesel sprays in engine-like conditions as it has been proved to be a very important step for the design of better and cleaner commercial engines. Due to the bigger share of passenger cars engines over heavy duty engines, the research has been mainly focused on the investigation using small nozzles. This paper studies two nozzles with diameters representative of those that can be encountered in heavy duty engines, with the objective of corroborating the conclusions gathered for small nozzles representative of passenger car engines. The experimental data have been acquired by state-of-the-art techniques and equipment, and serves two purposes: further the understanding of the physics involved in the injection event and spray evaporation; and provide a dataset to CFD models that can accurately predict the behavior of the injection event.The tests were performed in a constant pressure flow vessel that allows to simulate engine-like conditions (1000K and 15Mpa) with continuous flow. The injection system tested is a novel, common-rail, solenoid-actuated injector for heavy duty applications which operates up to 220Mpa. All experiments were performed in non-reacting conditions. The extended test matrix allowed to determine the influence of several parameters such as rail pressure, gas temperature, gas density, and nozzle geometry on the air–fuel mixing and evaporation process, by analyzing the spray penetration and spreading angle. Mie scattering and double-pass Schlieren optical configurations have been used to measure global liquid and vapor penetration, respectively.The data proves that spray penetration at low temperature can be up to 15% faster than spray penetration at high temperature conditions at the same density for the nozzles experimented, which limits the usability of low temperature experiments to infer the behavior of the injector at high temperature conditions. The data also shows that the nozzle with the biggest diameter provided the highest value of stabilized liquid length as expected. Also, when vapor phase is reached, the temperature has negligible effect on the global diesel spray morphology, and no influence on the tip penetration or on the spreading angle.

Rheological and aging properties of warm mix asphalt binders containing expanded vermiculite

ABSTRACTThe scope of this study was to investigate the high and intermediate temperature rheological and aging properties of warm mix asphalt binders modified by organo-expanded vermiculites. The rotational viscosity, complex modulus, and rutting parameter (G*/δ) increased and the penetration and phase angle decreased after modification of 3% organo-expanded vermiculites, indicating that the high temperature rheological properties of the warm mix asphalt binder have been improved. The warm mix asphalt binders containing 3% organo-expanded vermiculites demonstrate the lowest value of phase angle and the highest value of complex modulus compared with the studied binders. In addition, as a result of the rolling thin film oven test, the viscosity aging index of warm mix asphalt binder decreases, while the retained penetration increases obviously with the introduction of organo-expanded vermiculites. The warm mix asphalt binder with 3% organo-expanded vermiculites has more pronounced improvements in aging resistance in comparison with other studied modified warm mix asphalt binders.

Bionic Design for Mars Sampling Scoop Inspired by Himalayan Marmot Claw.

Cave animals are often adapted to digging and life underground, with claw toes similar in structure and function to a sampling scoop. In this paper, the clawed toes of the Himalayan marmot were selected as a biological prototype for bionic research. Based on geometric parameter optimization of the clawed toes, a bionic sampling scoop for use on Mars was designed. Using a 3D laser scanner, the point cloud data of the second front claw toe was acquired. Parametric equations and contour curves for the claw were then built with cubic polynomial fitting. We obtained 18 characteristic curve equations for the internal and external contours of the claw. A bionic sampling scoop was designed according to the structural parameters of Curiosity's sampling shovel and the contours of the Himalayan marmot's claw. Verifying test results showed that when the penetration angle was 45° and the sampling speed was 0.33 r/min, the bionic sampling scoops' resistance torque was 49.6% less than that of the prototype sampling scoop. When the penetration angle was 60° and the sampling speed was 0.22 r/min, the resistance torque of the bionic sampling scoop was 28.8% lower than that of the prototype sampling scoop.

Influence of Laser Power on the Shape of Single Tracks in Scanner Based Laser Wire Cladding

The shape of the cladding tracks is extremely important for producing layers or structures by adding them sequently. This paper shows the influence of the laser power of a diode laser in the range of 500 to 1000 W on the shapes of single tracks in scanner based laser wire cladding. The scanner was used to oscillate the beam perpendiculary to the welding direction. Stainless steel (ER 318 Si) wire with a 0.6 mm diameter was used as deposition material. Height, width, penetration, molten area and weld seam angles of single tracks were obtained from cross-sections at three different positions of each track. The influence of these different positions on the results depends on the traverse speed. The paper discusses this influence in respect to the heat dissipation in the substrate material.

３Ｄプリンターと高速遠心成形法を組み合わせたディーゼルノズルの製造

Diesel nozzle tips with multiple tapered spray holes were fabricated by P/M processing (high-speed centrifugal compaction) combined with resin cores made by three-dimensional printer. The nozzle tips with three tapered spray holes (inwardly larger) were obtained by the process, as net-shape formation. There was no obvious deformation during sintering shrinkage, therefore core shapes were precisely copied inside of the tips, forming tapered (8, or 16 deg.) spray holes in densely sintered products. Spray observation of the nozzles revealed that the highly tapered holes improved spray penetration and spray cone angle.

Laser Speckle Imaging to Monitor Microvascular Blood Flow: A Review.

Laser speckle is a complex interference phenomenon that can easily be understood, in concept, but is difficult to predict mathematically, because it is a stochastic process. The use of laser speckle to produce images, which can carry many types of information, is called laser speckle imaging (LSI). The biomedical applications of LSI started in 1981 and, since then, many scientists have improved the laser speckle theory and developed different imaging techniques. During this process, some inconsistencies have been propagated up to now. These inconsistencies should be clarified in order to avoid errors in future works. This review presents a review of the laser speckle theory used in biomedical applications. Moreover, we also make a review of the practical concepts that are useful in the construction of laser speckle imagers. This study is not only an exposition of the concepts that can be found in the literature but also a critical analysis of the investigations presented so far. Concepts like scatterers velocity distribution, effect of static scatterers, optimal speckle size, light penetration angle, and contrast computation algorithms are discussed in detail.

STUDY OF SPRAY CHARACTERISTICS OF BIODIESEL USING DIMENSIONLESS ANALYSIS UNDER NON EVAPORATING CONDITIONS

The spray characteristics of the fuel greatly influence emissions from diesel engines. Spray development plays a vital role in improving the combustion and emission characteristics of fuel because it directly affects the air- fuel mixture formation. The spray characteristics of fuel mainly depend on fuel injection process, fuel density, fuel viscosity, ambient pressure and temperature. Among these, the effect of fuel injection pressure is a very important parameter directly affecting spray structure. This study investigates the effects of fuel injection pressure on the spray characteristics such as spray angle and spray tip penetration in a constant volume chamber under non evaporating conditions by image processing techniques. The macroscopic spray characteristics were quantified using dimensionless analysis by examining the role of the dominating forces associated with liquid jet breakup. The Weber number, Reynolds number and air- to- fluid density ratio were used to capture the primary forces including the inertia, surface tension and aerodynamics drag forces. The Weber number has a more profound effect on the spray penetration and spray cone angle compared to the Reynolds number contribution. This analysis yielded dimensionless correlations for spray cone angle and spray tip penetration that provided important insight into the spray breakup and atomization process.

Study of biomechanical, anatomical, and physiological properties of scorpion stingers for developing biomimetic materials

Through natural selection, many animal organs have evolved superior mechanical properties and elegant hierarchical structures adaptive to their multiple biological functions. We combine experiments and theory to investigate the composition–structure–property–function relations of scorpion stingers. Their hierarchical structures and functionally gradient mechanical properties were revealed. Slow motion analysis of the penetration process of a scorpion stinger was performed to examine the refined survival skills of scorpions. An experiment-based mechanics model of the stinger was proposed, the results of which revealed an optimized range of penetration angle in an insertion event. Both theoretical and numerical results are in good agreement with our experimental measurements. The analysis method and physical insights of this work are potentially important for investigating a general class of sharp-edge biological materials, e.g., cattle horns, spider fangs, cat claws, and plant thorns.

Spray and Soot Formation Analysis by Means of a Quasi-Dimensional Multizone Model in a Single Cylinder Diesel Engine under Euro 4 Operating Conditions

An investigation has been carried out on the spray penetration and soot formation processes in a research diesel engine by means of a quasi-dimensional multizone combustion model. The model integrates a predictive non stationary 1D spray model developed by the Sandia National Laboratory, with a diagnostic multizone thermodynamic model, and is capable of predicting the spray formation, combustion and soot formation processes in the combustion chamber. The multizone model was used to analyze three operating conditions, i.e., a zero load point (BMEP = 0 bar at 1000 rpm), a medium load point (BMEP = 5 bar at 2000 rpm) and a medium-high load point (BMEP = 10 bar at 2000 rpm). These conditions were experimentally tested in an optical single cylinder engine with the combustion system configuration of a 2.0L Euro4 GM diesel engine for passenger car applications. The experimental spray tip penetration and spreading angle were evaluated on the basis of images acquired by means of a high-speed CCD camera, while the experimental trend of the in-cylinder soot concentration was derived by means of the two-color pyrometry method. The acquired experimental data have allowed useful information to be obtained for the assessment of the multizone model. Well-defined trends between some of the model parameters and the engine operating conditions (namely, speed and load) have been found and preliminary correlations have been developed

Effects of different biofuels blends on performance and emissions of an automotive diesel engine

The impact of blending Ultra Low Sulfur Diesel (ULSD) with different biofuels, obtained from Rapeseed Methyl Ester (RME) and Hydrotreated Vegetable Oil (HVO) respectively, on the performance and emissions of a European passenger car diesel engine was assessed in this paper.First, the hydraulic behavior of the common rail fuel injection system was analyzed in terms of injected volume, injection rate, spray global shape, single jet tip penetration and cone angle with both RME and HVO blends in comparison with neat ULSD.Afterwards, the impact of biofuel blends on engine full load performance was analyzed, both for the standard calibration and for a calibration which was specifically adapted to biofuels characteristics. The effects of biofuel blends on brake specific fuel consumption and on regulated exhaust emissions were then evaluated at different part load operating conditions, representative of the New European Driving Cycle.Finally, the sensitivity of the different fuels to different calibration settings, such as Exhaust Gas Recirculation (EGR) and injection timing, was studied in order to investigate which further emission benefits could be achieved by means of a more extensive engine re-calibration.

Analysis of spray injection in a light duty CR diesel engine supported by non-conventional measurements

Abstract The injection process is one of the relevant phenomena occurring in modern diesel engine considering also that the fuel properties have been continuously changing. The interaction mechanisms between fuel quality, engine technologies, and emissions need to be understood to find the most effective approach towards innovative combustion strategies and low-emission diesel engines. In this work, the injection process occurring in a direct injection (DI) Common Rail (CR) diesel engine has been investigated from the start of injection up to the start of luminous combustion using different techniques. 2D visible and infrared imaging has been applied in single cylinder optical engine for several injection strategies typical of passenger car engine (homologation cycle NEDC). The spray penetration and cone angle obtained by 2D imaging are compared with the results of a 1D consolidated model for transient spray developed by the Sandia National Laboratory. Some modifications to the model boundary conditions have been made in order to assess the effect of fuel–wall interaction. This provided qualitative information of the impinged fuel inside the piston bowl. Finally, a good correlation between the fuel mass impinging on the chamber wall and the particulate matter (PM) emissions measured at the engine exhaust was found. The results of this study could be helpful for the determination of the best injection strategies in a diesel engine in order to reduce PM emissions.