Penetration Angle Research Articles

Analysis of current phase influence on weld seam formation in double-wire DP-GMAW

Double-wire double-pulsed gas metal arc welding (DP-GMAW) experiments were conducted in the double pulse synchronous (DPS), alternating (DPA), and independent (DPI) phases. The effects of current phase on weld seam formation were analyzed. Experimental results showed that a stable welding process was achieved in all three current phases and the derived weld seams demonstrated little spatter, no hump, or undercut. Different current phases had little influence on weld reinforcement and width, but had a significant influence on weld penetration and toe angle. The fish-scale ripples of weld seams were prominent; specifically, the fish-scale ripples in the DPA phase were more prominent than those in other current phases. The penetration and penetration shape factor (PSF) in the DPA phase were at their highest while those in the DPS phase were at their lowest. In the DPS phase, the ferrite was coarse and in higher quantity, while the pearlite was relatively in lower quantity. In the DPA phase, the ferrite was finer and in lower quantity, while the pearlite was relatively in higher quantity and the microstructure was more uniform. Last, in the DPI phase, the microstructure appeared in a state between the DPS and DPA phases.

Potential of Laser Doppler Flowmetry in the Medical Needle Insertion Procedures.

Medical needle insertion procedures possess the risk of life-threatening blood vessel rapture. Here we report a compact laser Doppler Flowmetry (LDF) based system that has a potential of blood vessel detection in the vicinity of the moving needle. The developed LDF system comprises two optical fibers inserted into the needle (the probe), a laser unit and a photodetector. The latter collects the signal produced by photons, scattered from the moving red blood cells that is further converted into perfusion value. Using LDF system, we have been able to detect the flow independently from the needle penetration angle, site or depth. Moreover, we showed that the blood vessel can be identified inside the tissue phantom while the probe is moving. Our results demonstrate that the developed LDF system is flexible and compatible with different types of needles and thus has a potential in the needle insertion procedures.

Effect of the injection pressure and orifice diameter on the spray characteristics of biodiesel

The purpose of this study was to analyze the influence of the injection pressure and orifice diameter on the spray characteristics of soybean biodiesel. The macroscopic spray characteristics of the spray tip penetration (STP) and spray cone angle (SCA) were tested with a high-speed camera system. The microscopic spray characteristics, such as the statistical size distribution, Sauter mean diameter (SMD), representative diameters and dispersion boundary, were obtained using a Malvern laser particle size analyzer (PSA). The test results showed that with an increasing injection pressure, the STP and the SCA of the biodiesel increased, but the curves of size-volume distribution and cumulative volume distribution of the atomized droplets shifted to smaller diameters. The SMD and representative diameters decreased, and the dispersion boundary was reduced. Moreover, with a decreasing orifice diameter, longer STP and smaller SCA values were observed. Similarly, the size distribution curves of the atomized biodiesel droplets shifted to smaller diameters. The SMD and representative diameters were reduced, and the relative size range of the atomized biodiesel droplets was enlarged. Higher injection pressures and smaller orifice diameters improved the biodiesel atomization; however, the smaller orifice diameters caused an inhomogeneous size distribution of the atomized biodiesel droplets.

Combined influence of hydrogen direct-injection pressure and nozzle diameter on lean combustion in a spark-ignited rotary engine

A three-dimensional simulation on flow behavior and lean combustion in a hydrogen direct-injection gasoline rotary engine was implemented. The combined influence of hydrogen injection pressure (HIP) and nozzle diameter (HND) was numerically analyzed in the critical injection state. Results showed that with the increments of HIP and HND, further penetration and larger dispersion angle of jet-flow were presented. Increasing HIP led to larger jet-flow area and more jet-wall interaction, as well as greater deflection degree of hydrogen-flow after crashing upon the rotor surface. High-speed region expanded, while more jet-wall impingement occurred with the increment of HND. The spark ignited earlier and flame propagated faster as the HND modified smaller. As the HIP increased, the flame speed decreased slightly. The difference in the local Φ distribution and in-cylinder velocity field were the intrinsic mechanism of the HND impact, and the variation in the mixture concentration and TKE magnitude were the root causes of the HIP effect. The pressure and HRR traces were shifted to the downward clearly, while the peak positions were forming later as the HND extended larger. No perceptible difference in the peak positions of pressure and HRR were obtained with the HIP decrease, although pressure tended to increase along with heat release retard to be shortened. The combustion rate decreased with increments of HND and HIP, the timings of the initial consumption were delayed, and a proportional correspondence of reactants and intermediates was witnessed. The reduced NOx formation was obtained by increments of HND and HIP, and an inverse correlation can be seen between soot, CO, HC generations and NOx concentration. The scheme of 0.4 MPa HIP and 1 mm HND was the optimum configuration. Compared with a larger HND and higher HIP configuration, the peak pressure and maximum HRR were increased by 24.1% and 40.5%, and the productions of soot, CO, and HC were reduced by 55.7%, 61.5%, and 54.7%, respectively, though the NOx generation was increased to some extent. It was recommended in practice operations that the combination of lower HIP and smaller HND left a positive influence on improving the combustion characteristics of Wankel engines.

Spray characteristics of gasoline/PODE and diesel/PODE blends in a constant volume chamber

Polyoxymethylene dimethyl ethers (PODE) is an emerging alternative fuel, which has been extensively investigated and shows great potential to improve the combustion performance in both conventional diesel engine and novel combustion modes. In this paper, the spray characteristics of gasoline/PODE and diesel/PODE blends under different injection pressures and ambient pressures were investigated in a constant volume chamber under both non-evaporating and evaporating conditions. Experimental results show that under evaporating condition, the spray tip penetration of PODE is higher than gasoline, but shorter than diesel due to different volatility, along with smaller spray cone angle compared to diesel, and reduced spray cone angle can be obtained with higher injection pressure. Under non-evaporating condition, longer spray tip penetration and larger spray cone angle are observed with PODE. PODE is beneficial to reduce the equivalence ratio along the axial and radical directions for both gasoline and diesel due to its high oxygen content. In the meanwhile, PODE has larger SMD compared to gasoline, and smaller SMD for gasoline, diesel and PODE can be obtained by increasing injection pressure and lowering the ambient pressure. At last, the experiment data provided in this paper will also contribute to the spray model calibration.

Analysis of counterbore effect in five diesel common rail injectors

The present work assesses how the nozzle geometry, particularly the counterbore which is used in gasoline direct injection, could improve the fuel mixture when injecting in diesel engines, and ultimately, increase the thermal efficiency of the engine. Five different injector’s nozzles are tested using a parametric variation over counterbore dimensions. For this purpose, measurements of the rate of injection, spray momentum and non-evaporative visualization are performed. Comparison of the nozzles performance is assessed by the rate of injection and momentum, nozzle coefficients in the hydraulic part, and in terms of spray penetration and spray angle in the visualization part which describe the macroscopic characteristics of spray development. Minimal variation was found observing at the hydraulic characterization of the injectors. On the other hand, a more notable difference was found in the visualization experiments, in which the modified nozzles presented greater spray angles and smaller penetration than the original one without counterbore. This work provides an insight into the potential effects of using the popular counterbore -used in gasoline direct injection (GDI)- in a diesel injector.

Experimental and Analysis of Macroscopic Spray Characteristics of Biodiesel Blended with Di-n-butyl Ether Under Inert Conditions

In this study, spray characteristics of biodiesel blending with di-n-butyl ether (DBE15, DBE30) were investigated by experiment and analysis. Spray characteristics parameters including spray tip penetration and spray cone angle were used to compare the atomization effect under different injection pressures and ambient pressures. The spray tip penetration was logarithmically used to analyze the breakup time and to correct the empirical formula available from literature. The results show that the spray tip penetration of the blends added a certain proportion of di-n-butyl ether was shortened, and the spray cone angle was increased. In addition, the correction formula for introducing the density term was more suitable for the data of this experiment than the conventional empirical formula for predicting the spray tip penetration.

The Influence of Cylindrical Spray Chamber Geometry on the Evolution of High Pressure Diesel Sprays

While much is known on the effect of combustion chamber geometry on spray evolution in engines, less is known about its role in laboratory combustion chambers. This paper reports on a study, which investigates the effect of internal chamber geometry on the penetration and spreading angle of common rail nonreacting diesel sprays at room temperature conditions in a cylindrical constant volume chamber. This chamber has dimensions similar to those used in the literature. Spray chamber geometry was modified to yield three different chamber height-to-diameter ratios and two different nozzle stand-off distances. Sprays from three nozzles, two single-hole nozzles with different diameter and one twin-hole nozzle (THN), were examined for two injection pressures of 100 MPa and 150 MPa into two chamber pressures of 0.1 MPa and 5 MPa. To characterize the spray structure, a volume illumination method was used to study the spray tip penetration/speed and spread angle. For both injection pressures used with chamber pressure of 5 MPa, little sensitivity to vessel geometry was found in penetration distance and tip speed for variation in height to diameter ratio from 0.6 to 2.6 and variation in nozzle stand-off distance from 2 mm to 54 mm. For atmospheric chamber pressure, sensitivity to chamber geometry was evident and found to vary with nozzle type. Spread angle was found more largely affected by the calculation method and very sensitive to the image intensity threshold value for the cases investigated.

Numerical study on the influence of nozzle spray shape on spray characteristics using diesel and biofuel blends

Binary biofuel has a relatively higher viscosity compared to conventional diesel, which affects the spray injection and restricts the maximum evaporation. In this paper, the discrete phase model (DPM) was introduced to study the spray characteristics of four different biofuels, commercial diesel fuel (CDF), pure Melaleuca cajuputi oil, binary blend and ternary blend in a fuel injector. The spray characteristics of various biofuel blends are analyzed and compared to those of pure diesel. A numerical analysis was conducted to study spray characteristics such as Sauter mean diameter (SMD) and penetration for different biofuel blends. Verification and validation from the experimental results and numerical results are also presented. Furthermore, two types of injector hole geometries, cylindrical and conical, are studied. Simulations of the spray evolution are also discussed, highlighting the differences between the use of fossil diesel and biodiesel fuels in terms of spray penetration, atomization and cone angle. Usage of diesel fuel in the conical convergent nozzle gives higher liquid penetration. The results show that the DPM successfully predicted the spray characteristics, such as SMD and penetration of droplet particles, of all biofuel blends.

Sustainability of Individual EndoAnchor Implants in Therapeutic Use to Treat Type Ia Endoleak After Endovascular Aneurysm Repair

Purpose: To investigate changes in penetration depths and angles of EndoAnchor implants with initially good penetration after therapeutic use in endovascular aneurysm repair. Materials and Methods: Patients were selected from the Aneurysm Treatment Using the Heli-FX Aortic Securement System Global Registry (ANCHOR; ClinicalTrials.gov identifier NCT01534819). Inclusion criteria were (1) EndoAnchor implantation to treat intraoperative or late type Ia endoleak and (2) at least 2 postoperative computed tomography angiography (CTA) scans. Exclusion criteria were the use of adjunct procedures. Based on these criteria, 54 patients (44 men) with 360 EndoAnchor implants were eligible for this analysis. Penetration depth of each EndoAnchor implant into the aortic wall was judged as (1) good (≥2-mm penetration), (2) borderline (<2 mm or when there was a gap between the endograft and the aortic wall), or (3) no penetration. The penetration depth and longitudinal angles of EndoAnchors with good penetration were investigated on the last available postprocedure CTA scan. Endoleaks were also analyzed. Results: EndoAnchor penetration on the first postprocedure CTA scan was good in 187 (51.9%), borderline in 69 (19.2%), and missing in 104 (28.9%). On the last CTA scan, 182 (97.4%) of the 187 initially well-positioned EndoAnchors remained good. Five (2.6%) EndoAnchors in 4 patients changed configuration over time (4 became borderline and 1 became nonpenetrating), all without any clinical sequelae. The median orthogonal angles of the EndoAnchor implants with good penetration on the first and last CTA scans were 92° [interquartile range (IQR) 85, 98] and 90° (IQR 84, 97), respectively (p=0.822); for longitudinal angles, medians of 85° (IQR 71, 96) and 84° (IQR 70, 96) were found (p=0.043). Of the 18 (33%) patients who had a type Ia endoleak on the first postprocedure CTA, 6 resolved over time. Median follow-up was 13 months, during which no new type Ia endoleak was found. Conclusion: Despite the small number of EndoAnchors analyzed, this study showed that the sustainability of EndoAnchor implants with initially good penetration is satisfactory at 1-year follow-up. The vast majority of EndoAnchor implants with good penetration initially remained in good position; <3% of implants became borderline or nonpenetrating, without any clinical consequence.

Orientation effect in the neutron yield in deuterated Pd target bombarded by deuterium ion beam

At the ion accelerator HELIS at the LPI, the neutron yield is investigated from a deuteron-deuteron (DD) reaction in a deuterated Pd target, during an irradiation of its surface by a 20 keV deuterium (D) ion beam. The measurements of the neutron flux in the D beam direction are performed in dependence on the target angle $\ensuremath{\beta}$ with respect to the D beam axis using a multichannel detector based on ${\mathrm{He}}^{3}$ counters. A significant anisotropy in the neutron yield is observed, and it was higher by a factor of 2 at $\ensuremath{\beta}=0$ compared to that at $\ensuremath{\beta}=\ifmmode\pm\else\textpm\fi{}30\ifmmode^\circ\else\textdegree\fi{}$. The possible reasons for the anisotropy, including D ion channeling, are discussed. The orientation effect of increasing the relative probability of the DD reaction in Pd due to channeling was investigated by computer simulations using the bcm-2.0 code. The numerically obtained 20 keV D trajectories allow calculating the flux density of channeled D in dependence on the penetration depth and angle of incidence. The enhanced D flux density between crystal planes at a zero incident angle with respect to (200) Pd planes allows a qualitative explanation of the increase of the neutron yield in the DD reaction.

Vertebral artery segment at the suboccipital dural penetration site: an anatomical study using magnetic resonance imaging.

The morphology of the vertebral artery (VA) segment at the suboccipital dural penetration site has little been explored with magnetic resonance imaging (MRI). Therefore, the aim of this study was to examine the structure using MRI. In total, 94 patients underwent thin-sliced, contrast MRI in the axial, coronal, and sagittal planes involving the atlas, axis, occipital bone, and V3 and V4 segments of the VA. The VA segment at the suboccipital dural penetration site was well-delineated in 93% on the axial images and in 95% on the coronal images. The axial images showed that 82% of the VA penetration sites were located in the middle third of the dural sac. Meanwhile, the coronal images revealed that the heights of both VA penetration sites were located at the same level in 87%. The axial VA penetration angle, which is formed by the VA and tangential line of the dural sac, was 66 ± 11.9° on the right side and 61 ± 14.1° on the left side. The coronal VA penetration angle, which is formed by the tangential line of the VA and dural sac, was 111 ± 24.6° on the right side and 112 ± 19.9° on the left side. The morphology of the VA segment is considerably variable at the suboccipital dural penetration site, while most penetration sites are located in the middle third of the dural sac on axial MRI. These should be assumed during surgeries around the suboccipital VA penetration site.

Evaporating spray characteristics of a diesel-ethanol micro-emulsion

In the present study, evaporating spray characteristics of a diesel-ethanol micro-emulsion are reported for the first time under realistic engine-like conditions. A diesel-ethanol emulsion has been prepared by using 60% diesel, 20% anhydrous ethanol and 20% JME as an emulsifier. The evaporating spray characteristics in terms of liquid penetration, vapour penetration, liquid length and spread angle have been measured for the emulsion and compared with those of diesel. A high-pressure chamber with optical access is used in the present study for spray characterization. The chamber is filled with nitrogen which is heated to reach a final experimental condition of 50-bar pressure and 900-K temperature. A custom-made single-hole nozzle with a hole size of 190-µm has been used for the study. Surprisingly, the results have shown that the liquid penetration and the vapour penetration of the emulsion match closely with those of diesel showing no influence of droplet micro-explosion on spray characteristics. It is surmised that the enhanced rate of evaporation is compensated by evaporative cooling of low boiling point fuel and higher boiling point of JME leading to similar liquid length for the emulsion and diesel.

Experimental study on spray and emission characteristics of a diesel engine fueled with preheated bio-oils and diesel fuel

Bio-oils have been known with some advantages such as biodegradability, renewable, oxygen content, no-sulfur content. However, high viscosity, high surface tension and density due to the large structure may be the main causes strongly affecting the spray characteristics, mixture formation, combustion process, and emission characteristics of diesel engines running on bio-oils. In this work, the evaluation of the relationship between the spray parameters of used bio-oils including spray penetration (S) and cone angle (ɸ), and preheating temperature compared to fossil diesel fuel was conducted. Besides, the influence of the spray parameters on the breakup mechanism, brake thermal efficiency (ηe), heat release rate (HRR), and emission characteristics of an 80hp-diesel engine was reported. As a result, pure bio-oil was preheated to 105 °C to achieve the similarity of some physical properties and spray parameters compared to diesel fuel, but emission parameters of carbon monoxide (CO) and unburnt hydrocarbon (UHC) were 23.10% and 23.36% respectively higher. Meanwhile, brake thermal efficiency (ηe), and emissions of CO2, NOx, smoke were 3.36%, and 12.00%, 8.86%, 48.48% respectively lower than those of fossil diesel fuel. The findings in this paper showed further evidence in the direct use of pure biodiesel as a fuel for diesel engines.

Experimental study of the spray collapse process of multi-hole gasoline fuel injection at flash boiling conditions

In this study, fuel sprays of a 1-hole injector and a 6-hole injector were investigated under a wide range of subcooled and flash-boiling conditions using high-speed imaging in a constant-volume spray chamber. The fuel pressure was held constant at 15 MPa, and the fuel temperature was varied from 25 °C to 85 °C. Ambient pressure in the spray chamber was varied from 20 kPa to 200 kPa and the chamber temperature was held constant at 25 °C. The results show decreasing ambient pressure led to flash boiling for sprays from the 1-hole injector and consequently enhanced fuel atomization; however, the spray processes of the multi-hole injector were not well represented by the single-hole injector when considering spray collapse. For the 6-hole injector, the results showed plume interaction was more important than chamber density in controlling the spray characteristics. Specifically, expanded fuel plumes induced by flash boiling increased interaction between adjacent fuel plumes and consequently affected the spray structure. Slight plume interaction resulted in moderate spray collapse, shorter spray penetration and wider spray angles. Strong plume interaction triggered severe spray collapse, leading to longer spray penetration and smaller spray angles. Plume interaction started in the near nozzle region, and sustained interaction depended on the injector configuration and the superheat degree. At strong flash-boiling conditions (where the ratio of the ambient pressure to the fuel saturation pressure was less than 0.3), plume interaction increased with time and as the spray moved downward away from the nozzle exit due to fast fuel atomization and evaporation. The potential for spray collapse of a multi-hole injector was primarily attributed to the effects of the fuel properties, injector configuration and operating conditions (e.g. ambient pressure, fuel temperature and pressure, etc.) on the development of the plume width relative to changes in the distance between adjacent plumes. Adjusting the parameters to increase the distance between adjacent fuel plumes or decrease plume width, will decrease plume interaction and spray collapse can be suppressed, and vice versa.

Analysis of the position of EndoAnchor implants in therapeutic use during endovascular aneurysm repair

ObjectiveThe aim of this study was to analyze the penetration depth, angles, distribution, and location of deployment of individual EndoAnchor (Medtronic Vascular, Santa Rosa, Calif) implants. MethodsEighty-six primary and revision arm patients (procedural success, 53; persistent type IA endoleak, 33) treated for type IA endoleaks with a total of 580 EndoAnchor implants from a subset of the Aneurysm Treatment Using the Heli-FX Aortic Securement System Global Registry (ANCHOR) were included in this study. Procedural success was defined as the absence of a type IA endoleak on the first postprocedural computed tomography scan after the EndoAnchor implantation procedure. Endograft malapposition along the circumference was assessed at the first postoperative computed tomography scans and expressed as clock-face range and width in degrees and normalized such that the center was translated to 0 degrees. The position and penetration of each EndoAnchor implant were measured as the clock-face orientation. EndoAnchor implant penetration into the aortic wall was categorized as follows: good penetration, ≥2 mm; borderline penetration, <2 mm or ≥2-mm gap between the endograft and aortic wall; or no penetration. The orthogonal and longitudinal angles between the EndoAnchor implant and the interface plane of the aortic wall were determined. Location of deployment was investigated for each EndoAnchor implant and classified as maldeployed when it was above the fabric or in a gap >2 mm between the endograft and aortic wall due to >2-mm thrombus or positioning of the EndoAnchor implant below the aortic neck. ResultsA total of 170 (29%) EndoAnchor implants had maldeployment and were therefore beyond recommended use and not useful. After EndoAnchor implantation, the procedural success and persistent type IA endoleak groups had 3 (1%) and 4 (2%) EndoAnchor implants positioned above the fabric as well as 60 (18%) and 103 (42%) placed in a gap >2 mm, respectively. The amount of EndoAnchor implants with good, borderline, and no penetration was significantly different between both groups (success vs type IA endoleak) after exclusion of maldeployed EndoAnchor implants (235 [87.4%], 14 [5.2%], and 20 [7.4%] vs 97 [68.8%], 18 [12.8%], and 26 [18.4%], respectively; P < .001). Good penetration EndoAnchor implants were more closely aligned with a 90-degree orthogonal angle than the borderline penetration and nonpenetrating EndoAnchor implants. The longitudinal angle was more distributed, which was observed through all three penetration groups. ConclusionsIn this subcohort of ANCHOR patients, almost 30% of the EndoAnchor implants had maldeployment, which may be prevented by careful preoperative planning and measured intraoperative deployment. If endoleaks are due to >2-mm gaps, EndoAnchor implants alone may not provide the intended sealing, and additional devices should be considered.

Characterization of pure and blended biodiesel spray in a compression ignition engine by means of advanced diagnostics and 1D model

This paper provides a study of injection process in a research compression ignition engine fueled with Rapeseed Methyl Ester pure biodiesel and its blends by advanced optical diagnostics and 1D model. Experimental tests have been performed in an optical direct injection single-cylinder engine equipped with the Common Rail injection system of a real compression ignition engine. The injection strategies consisted of two events per cycle, the pilot and the main. The investigated conditions were representative of two engine operating points of the WLTC corresponding to two different engine speed and brake mean effective pressure values. The 2D visible imaging and the novel infrared (IR) technique have been applied to evaluate fuel spray parameters (i.e. penetration and cone angle) for liquid and vapor phases, respectively. Experimental results have been compared to data obtained with commercial diesel fuel available from previous authors’ works, underlining the main differences. Furthermore, to improve biodiesel spray knowledge, 1D model for diesel jets has been suitably modified to analyze RME spray. The model has been set up via collected experimental data. Pure fuel and blends properties have been evaluated using REFPROP® software. Once the model has been validated, it has allowed to calculate the equivalence ratio along both the jet axis and radial direction, and the amount of vapor fuel over time. The modified 1D model presented in this study could be an advanced and effective instrument to study injection process in the modern engines fed with biofuel, supporting experimental activities in order to reduce time and costs.

Accretion heated atmospheres of X-ray bursting neutron stars

Some thermonuclear (type I) X-ray bursts at the neutron star surfaces in low-mass X-ray binaries take place during hard persistent states of the systems. Spectral evolution of these bursts is well described by the atmosphere model of a passively cooling neutron star when the burst luminosity is high enough. The observed spectral evolution deviates from the model predictions when the burst luminosity drops below a critical value of 20–70% of the maximum luminosity. The amplitude of the deviations and the critical luminosity correlate with the persistent luminosity, which leads us to suggest that these deviations are induced by the additional heating of the accreted particles. We present a method for computation of the neutron star atmosphere models heated by accreted particles assuming that their energy is released via Coulomb interactions with electrons. We computed the temperature structures and the emergent spectra of the atmospheres of various chemical compositions and investigate the dependence of the results on the velocity of accreted particles, their temperature and the penetration angle. We show that the heated atmosphere develops two different regions. The upper one is the hot (20–100 keV) corona-like surface layer cooled by Compton scattering, and the deeper, almost isothermal optically thick region with a temperature of a few keV. The emergent spectra correspondingly have two components: a blackbody with the temperature close to that of the isothermal region and a hard Comptonized component (a power law with an exponential decay). Their relative contribution depends on the ratio of the energy dissipation rate of the accreted particles to the intrinsic flux from the neutron star surface. These spectra deviate strongly from those of undisturbed, passively cooling neutron star atmospheres, with the main differences being the presence of a high-energy tail and a strong excess in the low-energy part of the spectrum. They also lack the iron absorption edge, which is visible in the spectra of undisturbed low-luminosity atmospheres with solar chemical composition. Using the computed spectra, we obtained the dependences of the dilution and color-correction factors as functions of relative luminosities for pure helium and solar abundance atmospheres. We show that the helium model atmosphere heated by accretion corresponding to 5% of the Eddington luminosity describes well the late stages of the X-ray bursts in 4U 1820−30.

Effects of Vessel and Water Temperatures on Direct Injection in Internal Combustion Rankine Cycle Engines

This study focused on the effects of vessel and water temperatures on direct injection in internal combustion Rankine cycle engines through experimental and numerical methods. First, a study was carried out with schlieren photography using a high-speed camera for simultaneous liquid–gas diagnoses. Water was directly injected into a constant-volume vessel that provided stable boundaries. We wrote a MATLAB program to calculate spray tip penetration and cone angle from the images. For the further extension of boundary conditions, a numerical model was established and calibrated in AVL-FIRE for the thorough analysis of injection characteristics. Both experimental and numerical results indicated that injection and vessel temperatures have different effects on spray tip penetration. An increase in injected water temperature leads to shorter spray tip penetration, while the spray tip penetration increases with increasing vessel temperature. However, increased injection and vessel temperatures can both decrease the spray cone angle. Moreover, the simulation results also suggested that heat conduction is a main factor in boosting evaporation under top dead center conditions. When the internal energy of water parcels surges, these parcels evaporate immediately. These results are helpful and crucial for internal combustion engines equipped with direct water injection technology.

Effect of surface modification and knife penetration angle on the Quasi-Static Knife Penetration Resistance of para-aramid fabrics

The focus of this paper is to describe the effect of change in surface friction of single layer para-aramid (Twaron®) square woven fabric and change in knife penetration angle on its Quasi-Static Knife Penetration Resistance (QSKPR). The surface friction of fabric was changed by depositing SiO2 on its surface by using water glass as a precursor. Six different knife penetration angles (0°, 22.5°, 45°, 67.5°, 90° and 135°) were selected. Untreated and treated fabric samples were compared for change in QSKPR. It was observed that the deposition of SiO2 on the surface of Twaron® fabric increased the surface friction which resulted in the increase in QSKPR. The response of fabric against QSKPR changed from partial yarn cutting to individual yarn cutting in fewer steps and load was distributed to a larger area due to decrease in yarn slippage. The change in penetration angle changed the distance, knife cutting edge travelled to cut each next yarn(s) and when this distance increased, the QSKPR was reduced. The post-penetration image analysis of damaged fibres showed that the load distribution among warp and weft yarns was complementary and change in penetration angles changed the distribution of stabbing load among the warp and weft yarns. When yarns with higher tensile strength and less slippage were loaded, the fabric showed highest resistance to penetration. A QSKPR prediction model was also proposed at the end.