Penetration Height Research Articles

Interpulse Tig Welding of Titanium Alloy (TI-6Al-4V)

The unique properties of Titanium alloy (Ti-6Al-4V) like high strength to weight ratio, low density has made the alloy very useful material in the manufacturing of compressor blades, casings and other structural components of the gas turbine engines. The TIG welding is an arc welding process widely used in the fabrication of gas turbine engine components and its assembly. The Interpulse technique is the modified version of TIG welding process. Due to magnetic constriction and high frequency modulation of current in the interpulse technique, the arc is getting constricted which further minimizes the net heat input. In this experiment response surface optimization technique has been adopted to evaluate the effects of the input variables (main current, delta current, travel speed), on output responses (weld bead width, reinforcement height and area, penetration height and area and HAZ area). The outcome shall be beneficial in selecting suitable parameters to obtain the required shape and quality of the weld bead geometry.

An electric field penetration model for seismo-ionospheric research

We investigate the electric field penetration of the lithosphere–atmosphere–ionosphere coupling (LAIC) problem to study abnormal seismo-ionospheric disturbance. By directly solving the LAIC electric field penetration model at the high-latitude region, we find that the additional current induced at the ground surface flows into the ionosphere completely and further generates an abnormal ionospheric electric field. Therefore, we reasonably suggest that the electric field penetration of LAIC at middle- and low-latitude regions can be solved from the perspective of the ionospheric electric field model. The current from the downward atmosphere is treated as the source term. The simulation results demonstrate the following principal findings: (a) for the high-latitude region, the horizontal electric field in the ionosphere does not change with height and the vertical electric field can be neglected; (b) for the middle- and low-latitude regions, the intensity of the total horizontal electric field increases with the latitude and the vertical electric field is more obvious at low latitudes; and (c) the penetration height of the LAIC electric field in the ionosphere is lower at low latitudes than at high latitudes. We also find that according to the diurnal change of the ionospheric conductivity, the most efficient time for electric field penetration is between 00:00 and 04:00 local time.

Geologic Carbon Storage for Shale Gas Recovery

We consider the feasibility of a novel Carbon Capture, Utilization and Storage (CCUS) concept that consists in producing oil and gas from hydrocarbon-rich shales overlying deep saline aquifers that are candidates for CO2 storage. Such geological overlapping between candidate aquifers for CO2 storage and shale plays exists in several sedimentary basins across the continental US. Since CO2 reaches the storage formation at a lower temperature than the in-situ temperature, a thermal stress reduction occurs, which may lead to hydraulic fracturing of the caprock overlying the aquifer. In this work, we use a thermo-hydro-mechanical approach for modelling a caprock-aquifer-baserock system. We show that hydraulic fracturing conditions are induced within the aquifer by thermal stress reduction caused by cooling and that hydraulic fractures eventually propagate into the lower portion of the shale play. Nonetheless, fracture height of penetration in the caprock is considerably short after 10 years of injection, so the overall caprock sealing capacity is maintained. To maximize the benefit of the proposed CCUS method, CO2 injection should be maintained as long as possible to promote the penetration depth of cooling-induced hydraulic fractures into organic-rich shales. Though drilling a horizontal well in the lower portion of the shale to produce hydrocarbons from the induced hydraulic fractures may not be technically feasible, hydrocarbons can still be produced through the injection well. The production of hydrocarbons at the end of the CO2 storage project will partly compensate the costs of CCS operations.

Effect of Process Parameters on Weld Bead Geometry of Mild Steel Plate in Double Pulse GMAW

This work presents the effect of various input process parameters on weld bead geometry of mild steel plate in double pulse gas metal arc welding. Bead penetration, bead width and bead height are considered as output parameters. Fuzzy model is developed to predict the geometry of weld bead and are compared with experimental values. The mean analysis is performed to know the effect of each input parameters on output parameters. It is observed that wire feed rate and welding speed have more effect on bead geometry whereas amplitude has the least effect. It is also found that fuzzy model can predict the output parameters with good accuracy in double pulse gas metal arc welding.

Comparative analysis among deterministic and stochastic collision damage models for oil tanker and bulk carrier reliability

The incidence of collision damage models on oil tanker and bulk carrier reliability is investigated considering the IACS deterministic model against GOALDS/IMO database statistics for collision events, substantiating the probabilistic model. Statistical properties of hull girder residual strength are determined by Monte Carlo simulation, based on random generation of damage dimensions and a modified form of incremental-iterative method, to account for neutral axis rotation and equilibrium of horizontal bending moment, due to cross-section asymmetry after collision events. Reliability analysis is performed, to investigate the incidence of collision penetration depth and height statistical properties on hull girder sagging/hogging failure probabilities. Besides, the incidence of corrosion on hull girder residual strength and reliability is also discussed, focussing on gross, hull girder net and local net scantlings, respectively. The ISSC double hull oil tanker and single side bulk carrier, assumed as test cases in the ISSC 2012 report, are taken as reference ships.

A numerical study of spray/wall impingement based on droplet impact phenomenon

A new spray/wall impingement model is purposed based on droplet impact experiments and droplet morphology dynamics. Various splashing modes are summarized and analyzed based upon earlier research on droplet impact and conservation laws. Corona splash and prompt splash are distinguished in the new spray/wall impingement model taking the incident and wall conditions into consideration. Morphology dynamics of droplet impingement is analyzed and coupled into the conservation equations, which helps to obtain more accurate dynamic results of splashing droplets. The new wall impact model is validated in a constant volume combustion system under different conditions. Two different fuels, including n-tridecane and diesel, are adopted for spray impingement validations. It is found that this new model shows good performance in predicting impinging spray properties, including radius penetration and splashing height, in wide jet conditions.

Effect of Nozzle Exit Turbulence on the Column Trajectory and Breakup Location of a Transverse Liquid Jet in a Gaseous Flow

This study examines the effect of fully developed turbulent flow at the exit of nozzle/injector on the trajectory and column breakup location of a liquid jet injected transverly into a gaseous crossflow. Liquid jet trajectory and column breakup for different nozzle geometries at different velocities of liquid jet and crossflow are analytically and experimentally Investigated. Shadowgraph imaging technique is used to determine the jet trajectory and breakup location of a transverse liquid jet in a uniform airflow. Particle image velocimetry (PIV) is used to measure the near-field velocity profile of a liquid jet discgarged into a quiescent atmosphere. The experimental results show a higher penetration and breakup height for the liquid jet ensuing from a nozzle with a smaller length to diameter ratio. This is due to the surface irregularities of the liquid column of a turbulent jet, which breaks up and consequently follows the cross airflow sooner. In order to capture the effect of turbulence, the analytical trajectory correlation developed in our previous studies is modified to account for the discharge coefficient of a nozzle. The discharge coefficient is estimated indirectly by comparing the liquid column trajectory predicted by the modified analytical correlation with that determined experimentally. The indirectly determined discharge coefficient is then used in the analytical correlation for predicting the breakup height of a transverse liquid jet. The results predicted using this approach are in good agreement with the experimental data of the present study at standard temperature and pressure (STP) test conditions.

Characterization of kerosene distribution around the ignition cavity in a scramjet combustor

Kerosene distribution before its ignition in a scramjet combustor with dual cavity was measured using kerosene-PLIF under transverse injection upstream of the cavity and different injection pressures. The simulated flight condition is Ma 5.5, and the isolator entrance has a Mach number of 2.52, a total pressure of 1.6MPa and a stagnation temperature of 1486K. Effects of injection pressure on fuel distribution characteristics were analyzed. The majority of kerosene is present in the cavity shear layer as well as its upper region. Kerosene extends gradually into the cavity, almost, at a constant angle. Large scale structures are evident on the windward side of kerosene. The cavity shear layer plays an important role in determining the kerosene distribution and its entrainment into the cavity. The middle part of cavity is the most suitable location for ignition as a result of a favorable local equivalent ratio. As the injection pressure increases, the penetration height gets higher with the rate of increase getting slower at higher injection pressure. Meanwhile, the portion of kerosene entrained into cavity through shear layer becomes smaller as injection pressure increases. However, the kerosene entrained into cavity still increase due to the increased mass flow rate of kerosene.

Numerical Investigation of Various Fuel Injection Angles on Interaction in Cold Kerosene-fueled Supersonic Flow

The incident shock wave strongly affects the transversal injection field in cold kerosene-fueled supersonic flow, possibly due to its affecting the interaction between incoming flow and the fuel through various operation conditions. Optimum selection of fuel injection parameters indicates optimum interaction between incoming flow and fuel. Based on three dimensional Couple Level Set & Volume of Fluids (CLSVOF) approach, a detailed Computational Fluid Dynamics model of a cold kerosene-fueled scramjet combustor is developed in this study. Next, the effects of various injection angles on the interaction between incident shock wave and transversal cavity injection are addressed. The injection angles are specified from 45̊ to 135̊ in 45̊increments when other operation parameters, i.e. the injection diameter, velocity and pressure drop are all constant. The CLSVOF-based predictions are focused on penetration height, span-wise expansion area, angle of shock wave and sauter mean diameter (SMD) distribution of the kerosene droplets. Our findings show that the penetration depth, span-wise angle and expansion area of the transverse cavity jet all increased with the injection angle, and that the kerosene droplets are more prone to breakup and atomization at the outlet of the combustor for the injection angle of 45̊. This study demonstrates the effectiveness of CLSVOF modeling for better understanding of kerosene-fueled supersonic mixing and scramjet combustor design improvement.

Penetration height of transitional round fountains in a linearly stratified fluid

The transition to asymmetry of transitional fountains is further complicated by the stratification of the ambient fluid. In this study, a series of three-dimensional direct numerical simulations were carried out for transitional round fountains in linearly-stratified fluids over the ranges of 100 ≤ Re ≤ 400, 1 ≤ Fr ≤ 8 and 0.0 ≤ s ≤ 0.3, where Fr, Re and s are the Froude, Reynolds, and dimensionless temperature stratification parameters, respectively, to examine, both qualitatively and quantitatively, the effect of these parameters on their axisymmetric transition and their maximum penetration heights. The results show that when Fr or Re are small enough, a fountain remains axisymmetric for all time; however, when Fr or Re are increased sufficiently, the fountain will be axisymmetric initially, before becoming asymmetric and unsteady, ultimately reaching a fully developed quasi-steady stage when the maximum fountain penetration height fluctuates over a constant, time-average, value. The stratification is found to play a positive role to stabilize the flow and to reduce or even to eliminate the asymmetric behavior. The numerical results were also used to develop a series of scaling relations, in conjunction with the scalings obtained with dimensional analysis, for the initial and time-averaged fountain penetration heights, and the time for the fountain to attain the initial penetration height. It is further found that in general these characteristic parameters are strongly dependent on Fr and s, while only weakly dependent on Re.

Effect of In-Hole Roughness on Film Cooling From a Shaped Hole

While much is known about how macrogeometry of shaped holes affects their ability to successfully cool gas turbine components, little is known about the influence of surface roughness on cooling hole interior walls. For this study, a baseline-shaped hole was tested with various configurations of in-hole roughness. Adiabatic effectiveness measurements at blowing ratios up to 3 showed that the in-hole roughness caused decreased adiabatic effectiveness relative to smooth holes. Decreases in area-averaged effectiveness grew more severe with larger roughness size and with higher blowing ratios for a given roughness. Decreases of more than 60% were measured at a blowing ratio of 3 for the largest roughness values. Thermal field and flowfield measurements showed that in-hole roughness caused increased velocity of core flow through the hole, which increased the jet penetration height and turbulence intensity resulting in an increased mixing between the coolant and the mainstream. Effectiveness reductions due to roughness were also observed when roughness was isolated to only the diffused outlet of holes, and when the mainstream was highly turbulent.

Interaction behavior of triple transitional round fountains in a homogeneous fluid

In this study, the PIV and flow visualization techniques and three-dimensional direct numerical simulation are used to investigate the behavior of triple transitional round fountains, which are aligned along a straight line, interacting with each other in a homogeneous fluid over the ranges of 1 ≤ Fr ≤ 10 and 100 ≤ Re ≤ 1000, at a fixed spacing of D/X0=6, where Re and Fr are the Reynolds and Froude numbers, D is the spacing between the two neighbouring fountain sources, and X0 is the radius of orifices at the fountain source, respectively. The results show that the interaction behavior of triple transitional round fountains, over the ranges of Re and Fr studied, is dominated by the bobbing and flapping motions, and is either steady, or unsteady weakly multi-modal, or unsteady strongly multi-modal. In a steady interaction, the bobbing-flapping motions are only present in its initial development stage and the interaction will attain a steady state in the later stage in which the bobbing-flapping motions are no longer present. In contrast, in an unsteady interaction, the interaction remains unsteady all the time and the bobbing-flapping motions are present at all stages. Among all cases considered, a steady interaction occurs at Re ≤ 300 with Fr=1 and at Re=100 with Fr ≤ 5; an unsteady weakly multi-modal interaction occurs at Re=100 with 6 ≤ Fr ≤ 10, at 200 ≤ Re ≤ 300 with 2 ≤ Fr ≤ 10, and at Re=400 with Fr=1; and an unsteady strongly multi-modal interaction occurs at 600 ≤ Re ≤ 1000 with Fr=1 and at 400 ≤ Re ≤ 1000 with 2 ≤ Fr ≤ 10. Such interaction behavior is found to be similar to that of twin transitional round fountains over comparable ranges of Re and Fr, as discovered by us in an earlier study. It is also found that the two interaction regions formed by the three fountains have essentially symmetrical behavior about the middle fountain for all cases considered. Furthermore, the maximum fountain penetration heights and the maximum thicknesses of the interaction regions of the triple transitional round fountains are quantified with the experimental and numerical results and compared to the available scalings for single fountains at comparable Fr and Re values. Several scaling relations are then developed for these parameters over the ranges of Fr and Re considered.

Numerical investigation of scale effect of various injection diameters on interaction in cold kerosene-fueled supersonic flow

The incident shock wave generally has a strong effect on the transversal injection field in cold kerosene-fueled supersonic flow, possibly due to its affecting the interaction between incoming flow and fuel through various operation conditions. This study is to address scale effect of various injection diameters on the interaction between incident shock wave and transversal cavity injection in a cold kerosene-fueled scramjet combustor. The injection diameters are separately specified as from 0.5 to 1.5mm in 0.5mm increments when other performance parameters, including the injection angle, velocity and pressure drop are all constant. A combined three dimensional Couple Level Set & Volume of Fluids (CLSVOF) approach with an improved K-H & R-T model is used to characterize penetration height, span expansion area, angle of shock wave and sauter mean diameter (SMD) distribution of the kerosene droplets with/without considering evaporation. Our results show that the injection orifice surely has a great scale effect on the transversal injection field in cold kerosene-fueled supersonic flows. Our findings show that the penetration depth, span angle and span expansion area of the transverse cavity jet are increased with the injection diameter, and that the kerosene droplets are more prone to breakup and atomization at the outlet of the combustor for the orifice diameter of 1.5mm. The calculation predictions are compared against the reported experimental measurements and literatures with good qualitative agreement. The simulation results obtained in this study can provide the evidences for better understanding the underlying mechanism of kerosene atomization in cold supersonic flow and scramjet design improvement.

Analysis of emulsions concentration changes during imbibition in porous sorbents

The stabilized emulsions removal from the aqueous systems is supposed to be an issue as important as the free oil products recovery. This work was conducted to investigate the mechanisms of oil-in-water emulsions sorption in a non-woven oleophilic/hydrophobic material forced by the capillary suction pressure, and the saturation level of such material during this process. It ensures the effective application of the sorbents and facilitates the development of alternative high-performance sorptive materials that can contribute to diminishing of the negative consequences of the aquatic environment contamination. The main aspect investigated in this research work was kinetics of the imbibition process in the porous media to define the optimal time of sorption and the height of the emulsions penetration. The measurement of the dispersed phase concentration changes with the increase in an emulsion front in the porous medium using the nephelometrical method is the advanced approach in the field of assessment of sorbents efficiency. The tendency of the imbibed emulsion concentration decrease versus the height was observed, which depended strongly on the viscosity and the initial composition of a penetrating liquid. The observed process was described by the mathematical model based on Hill equation.

Correlations for maximum penetration heights of transitional plane fountains in linearly stratified fluids

In this study, a series of three-dimensional direct numerical simulations (DNS) were carried out using ANSYS Fluent for transitional plane fountains in linearly stratified fluids with the Reynolds number (Re), Froude number (Fr) and dimensionless temperature stratification parameter (s) over 28≤Re≤300, 3≤Fr≤10, and 0.1≤s≤0.5, to study and quantify the effects of these governing parameters on the maximum fountain penetration height, including the initial one during the early developing stage and the time-averaged one at the quasi-steady state, as well as the time to reach the initial maximum penetration height. The results show that both the initial and time-averaged maximum fountain heights as well as the time to attain the initial maximum fountain height increase with Fr but decrease with s, whereas the effect of Re is negligible, and the fluctuations of the maximum fountain penetration height at some specific locations at the quasi-steady state also follow the similar trends. Empirical correlations to quantify the effects of Fr, s and Re on these bulk fountain behavior parameters were obtained from the DNS results over the ranges of Fr, s and Re considered.

Performance of Some Hybrid Rice Combinations Under Different Irrigation Intervals and Sowing Dates

Two field experiments were conducted at the farm of Sakha Agricultural Research Station – Sakha, Kafr- El sheikh governorate, Egypt during 2014 and 2015 seasons to study the performance of some hybrid rice combinations to different dates of sowing and various irrigation intervals. Three hybrid rice combinations, namely; SK-2034H (H1), SK-2046H (H2) and SK-2151H (H3) were used under three dates of sowing (May, 1, May, 15 and May, 30) with three irrigation intervals i.e. every 4 days, every 8 days and every 12 days. A split-split plot design with four replications was used. The three dates of sowing were allocated in the main plots and the three irrigation intervals were devoted in sub-plots, while sub- sub were received the three varieties. The studied characters were light penetrations, leaf area index (LAI), chlorophyll content, crop growth rate, plant height, root depth, number of panicles /m2, 1000-grain weight, panicle length, number of spikelets / m2 *1000, spikelets-leaf area ratio, number of grains/ panicle, grain yield (t/ha) and straw yield (t/ha). The main results indicated that May first followed by May,15 caused an increase in all the previous characters except light penetration and plant height at maximum tillering and late booting. As for irrigation intervals, either irrigation every 4 days or every 8 days were the best for all the studied characters except light penetration and rood depth which reached to the maximum value under irrigation every 12 days. Results also revealed that the hybrid SK-2034 H (H1) surpassed the other two studied hybrids in most of the studied characters and produced the greatest grain yield moreover saved reasonable amount of irrigation water (984,3 m3/ha ) under 8 days intervals. So it can be concluded that cultivate the hybrid SK-2034 H (H1) hybrid through the first two weeks of May and irrigate it every 8 days intervals was the best combination to get higher yield and save of irrigation water without significant reduction in the yield.

Effects of micro-ramp on transverse jet in supersonic crossflow

The effects of micro-ramp on the characteristics of transverse jet were investigated by the LES simulation at Mach 2.7, with recycling-rescaling method applied to reproduce the turbulent boundary layer. The transverse nitrogen jet in front of micro-ramp and behind micro-ramp were studied by comparison with plate jet. It is found that the micro-ramp can improve the penetration height obviously, while placing jet orifice behind micro-ramp, due to the low freestream momentum in ramp wake. On the other hand, when placing the jet orifice in front of micro-ramp, the improvement in penetration is quite slight, because most injection is above the boundary layer and micro-ramp has little influence on the main flow. It is also observed that unlike the periodic Kevin Helmholtz (K–H) vortices appeared in ramp wake, the periodic K–H vortices are not achieved in jet cases.

A model problem for a supersonic gas jet from a moon

Some celestial bodies such as planets, moons and comets (here referred to as moons for simplicity) emit jets of material at speeds that in some instances are large enough to escape gravity. Previous investigations have shown this problem to be highly complex, e.g. involving multi-phase flows, phase changes, radiation and gas rarefaction effects. In order to learn from exploring a manageable parameter space, and to provide a limiting case, the present study considers a much simpler model situation in which the material of the jet is an inviscid, non-heat-conducting, perfect gas that issues radially at the surface of the moon with sonic velocity. Theoretical considerations show that the escape velocity of a gas is much smaller than that of a solid body. An analytical solution is obtained for the maximum height reached by a jet in steady flow. A computational parameter study of unsteady, inviscid, axisymmetric flow, including the effect of an atmosphere, provides a rich picture of the features and behaviour of the model jet. The deficit of the computed maximum steady-state penetration height below the isentropic theoretical value may be explained by the effect of the atmosphere and of dissipation in shock waves that occur in the computed flows. Many of the features of the gas jet are qualitatively mirrored in an experiment using a water flow analogy in which the gravitational field is simulated by a surface of suitable shape.

A laboratory investigation into the influence of a rigid vegetation on the evolution of a round turbulent jet discharged within a cross flow

The study of buoyant jets, those between pure jets and plumes, has been carried out with ever greater frequency over recent years due to its application in different practical engineering fields, i.e. appropriate design of outfalls for the disposal of municipal and industrial waste waters. The dispersion of waste and the related dilution of pollutants are governed by the mean-flow and turbulence characteristics of the resulting jets, which themselves depend on environmental conditions.The present study deals with how a uniform cross-stream with a channel bed surface covered by rigid emergent stems affects the behaviour of a circular turbulent buoyant jet. The time-averaged temperature and velocity fields are investigated in order to understand jet diffusion and penetration within the ambient fluid.The examination and comparison of the measured scalar and vector quantities show that the presence of emergent vegetation in the receiving environment affects both the average flow field and the jet structure, reducing the mean channel velocity, with a notable increase in jet penetration height and dilution compared to the test case without vegetation. This result is confirmed by the several vertical profiles of the mean scalar concentration and the normalized vertical velocity component along the channel centre plane. Moreover, the rigid emergent vegetation and its driven instabilities promote a distortion of the mean concentration and normalized axial velocity component profiles in the trajectory-based coordinate system.

Numerical simulations of spray jet in supersonic crossflows using an Eulerian approach with an SMD model

Spray jet in supersonic crossflows was investigated numerically using an Eulerian two-fluid model based on kinetic theory. Characteristic analysis was performed in three-dimensional condition to demonstrate the hyperbolic nature of the dispersed phase governing equations system. An SMD model was proposed according to the experimental data and incorporated into the simulations. Numerical tests were designed to explore the effects of droplet sizes on the predicted results. The penetration height and spray width were validated against the empirical correlations. The S-shaped distributions of the droplet velocity and Weber number were well described with the proposed SMD model, and good agreements with the experimental measurements were also achieved for the volume flux and droplet number density, respectively. The spray phase pressure reached its maximum near the bottom floor due to the high spray phase density there. The gas phase turbulence reduced the dissipation of the spray phase turbulent kinetic energy which was found growing below the middle height of the spray plume.