Liquid Penetration Research Articles

Spray and combustion characteristics of polyoxymethylene dimethyl ethers and diesel blends in a constant volume chamber

Polyoxymethylene dimethyl ethers (PODE) are newly appeared promising oxygenated additive which can significantly reduce soot emissions of diesel engines. In this study, the spray and combustion characteristics of the blends of diesel with different PODE blending ratio of 0%, 20%, 50% and 100% by volume are investigated in a constant volume chamber (CVC) under 100 MPa, 120 MPa and 140 MPa injection pressures. The spray results show that liquid spray tip penetration (STP), average spray angle (ASA) and spray projected area (SPA) all decrease with PODE blending ratio under 4 MPa ambient pressure and 573 K ambient temperature. The addition of PODE in diesel can significantly reduce the soot formation and the integrated natural flame luminosity (INFL). Under 100 MPa injection pressure, the time integral sum KL in whole combustion duration of D100, P20, P50 and P100 are namely 107.35, 2.66, 0.27 and 0.08. When the PODE blending ratio are 50% and 100%, nearly no yellow flame can be observed in the combustion duration. The chemical structure of PODE plays an important role in reducing soot formation.

The Corrected Distortion model for Lagrangian spray simulation of transcritical fuel injection

In this work, we present a detailed implementation and validation of the droplet modeling framework proposed by Dahms and Oefelein (2016) into the engine commercial CFD software CONVERGE using the User Defined Function (UDF) interface. The model accounts for the nonlinear deformation and oscillation experienced by liquid spray droplet injected into high pressure and temperature. Lagrangian spray simulations of Engine Combustion Network (ECN) Spray A are performed. Model validation against standard experimental measurements of liquid velocity, vapor mixture fraction is conducted. To perform more rigorous model validation, new experimental measurements based on Diffused Back Illumination (DBI) are introduced. The new measurements are processed for Projected Liquid Volume (PLV), which offers as close as possible one-to-one model validation for liquid penetration while offering new insights into the spray physics. Comparison with a One-D model based on adiabatic mixing theory by Siebers (1999) and Desantes et al. (2007) are also conducted. Through these model validation exercises, it is shown that the new framework improves liquid-phase penetration predictions, following a tendency for enhanced evaporation, compared to the standard approach for both Reynolds Average Navier Stokes (RANS) and Large Eddy Simulation (LES). At the liquid length, maximum mixture fraction values predicted by the new approach are in good agreement those of an adiabatic mixing model. Qualitative analysis of the spray behaviors during the early stage of the injection process reveals that the proposed framework predicts significant increase in droplet evaporation rate with lower drop drag compared to the current standard approach.

Numerical study of droplet impingement on surfaces with hierarchical structures

Decorating a surface with pillars and grooves has been proved effective in enhancing its hydrophobicity. However, the poor stability of the non-wetting state is the main reason for limiting the practical applications of textured surfaces. In this study, a textured surface, with primary structures (taller) to improve hydrophobicity and secondary structures (shorter) to stabilize the non-wetting state, is proposed. The effects of the secondary structure, impingement position, and Weber number (We) on the deformation, penetration, and wetting state of a droplet on this surface are investigated by means of a three-dimensional direct numerical simulation (DNS). The results show that decorating the surface with hierarchical structures enhances both the surface hydrophobicity and the non-wetting stability due to the large breakthrough pressure brought by the secondary structures. The penetration depth and the emptying time decrease with the increase in the height of secondary structures. The impingement position, at the groove or the ridge, also plays a vital role in the non-wetting stability because of the difference in conversion between kinetic energy and surface energy. Surfaces with hierarchical structures require a significantly higher We to trigger the liquid penetration at the secondary structures. We also influences the contact time and emptying time due to the abrupt change of surface roughness when liquid slides down the sidewall of the primary groove and then touches the secondary ridge. The two-step wetting transition found on the structured surface is well explained by the correlation of the Laplace’s law, the Young’s equation, and the Gibbs extension. It is seen that such hierarchical structures offer significant possibilities for the development of hydrophobic surfaces.

Fabrication of MnO2 Nanowires@Ag/Cellulose Laminated Membranes with Unidirectional Liquid Penetration for Personal Thermal Management Applications

Controllable and reliable fabrication of wearable materials with tunable structures and integrated functionalities is urgently required for personal thermal management. Here, MnO2 nanowires@Ag/cellulose laminated membranes with infrared insulation, antibacterial, and unidirectional liquid penetration properties assembled were fabricated by hydrophobic cellulose, hydrophilic cellulose, and ultralong MnO2 nanowires@Ag in vacuum filtration and magnetron sputtering methods. The results indicated that nanosilver coating with high infrared radiation reflectivity and excellent electrical conductivity was successfully fabricated onto MnO2 nanowire surfaces, resulting in infrared insulation properties of the laminated cellulose membranes. In addition, the laminated membranes exhibit unidirectional liquid penetration properties that can enhance the wearing comfort. In antibacterial tests against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, the high antibacterial activity is revealed. These results indicate the promising potential of the laminated cellulose membranes for tackling personal thermal management issues related to wearable applications.

Maximum spreading of liquid droplets impact on concentric ring-textured surfaces: Theoretical analysis and numerical simulation

It is fundamentally significant to predict the maximum spreading of liquid droplets impact on textured surfaces. However, relevant work is very limited. Considering the effects of contact line pinning and liquid penetration into textures, a theoretical model to predict the maximum spreading factor on concentric ring-textured surfaces is developed. Validated with numerical simulations conducted by an effective, sharp-interface, continuum level modeling method, this model has shown a good predicting performance. It is demonstrated that in the viscous regime, the viscous dissipation arising from liquid penetration into textures has a considerable effect on the maximum spreading factor, whereas the effects of the contact line pinning and surface energy are negligible. Meanwhile, as viscous dissipation becomes more dominant, the effect of texture gap on maximum spreading is less visible. The phase diagram of the wetting state at maximum spreading is also provided. We indicate that the intermediate wetting state is favorable under small Reynolds number and narrow texture gap, while the partial wetting state is supported under the opposite conditions.

Perturbations of the Depth of Liquid Penetration Into the Capillary During Bubble Departures

Abstract In the present paper, the influence of bubble size on liquid penetration into the capillary was experimentally and numerically studied. In the experiment, bubbles were generated from a glass capillary (with an inner diameter equal to 1 mm) in a glass tank containing distilled water, tap water or an aqueous solution of calcium carbonate. These liquids differ in the value of their surface tension, which influences the bubble size. During experimental investigations, air pressure fluctuations in the gas supply system were measured. Simultaneously, the videos showing the liquids’ penetration into the capillary were recorded. Based on the videos, the time series of liquid movements inside the capillary were recovered. The numerical models were used to study the influence of bubble size on the velocity of liquid flow above the capillary and the depth of liquid penetration into the capillary. It was shown that the air volume flow rate and the surface tension have the greatest impact on the changes of pressure during a single cycle of bubble departure (Δp). The changes in pressure during a single cycle of bubble departure determine the depth of liquid penetration into the capillary. Moreover, the values of Δp and, consequently, the depth of liquid penetration can be modified by perturbations in the liquid velocity above the capillary outlet.

Influence of paper properties on adhesive strength of starch gluing

Abstract The effect of paper properties on the strength of starch gluing for Kraft sack papers has been investigated. We analyzed the effect of surface roughness, wettability and glue penetration. Surface roughness was found not to be related to gluing strength, also surface wetting measured by contact angle showed only a weak relation. Liquid penetration measured by ultrasound (ULP) was found to have a substantial correlation to gluing strength. Comparing ULP liquid penetration speed with actual glue uptake during the gluing process we found that they are only moderately connected. We are attributing this to the fact that the penetration and spreading of the glue on the paper is driven by applying an external pressure during the gluing process, which is not the case for the liquid penetration measurement. Investigating how asymmetrical glue penetration affects gluing strength we found that the relationship was low. The best indication for gluing strength turned out to be the surface wetting/substrate swelling parameter from the ultrasonic liquid penetration measurement. We conclude that the main parameter capturing gluing strength combines the influence of fiber wetting and penetration of the glue into the fibers.

Numerical characterization of thermalhydraulics of subcooled flow boiling through the annular core of a test facility

Presence of thermal nonequilibrium inside the vertical boiling channels can significantly influence the thermalhydraulic characteristics of BWRs. The nature of thermal interactions across interfaces is susceptible to numerous operational factors. Present study reports a comprehensive numerical investigation of subcooled boiling in a vertical annulus with heated outer wall during upflow of subcooled water. Separate conservation equations are solved for both liquid and vapor phases, coupled with wall heat flux partitioning approach and relevant closure relations. Developed computational framework is validated using experimental data from literature and employed for subsequent appraisal of one heated channel of the PCNCTF test facility. Three important transition locations are identified along the heated surface. The model efficiently emulates first vapor generation at ONB and appreciable vapor generation beyond OSV, along with gradual thickening of superheated liquid layer and penetration of vapor towards the unheated wall. Saturated boiling initiates after disappearing of convective heat flux, with a peak in quenching contribution. Appearance of actual boiling boundary is significantly delayed due to subcooled boiling, occasionally continuing the entire phase-change process in subcooled mode. Effect of heat flux, mass flux and pressure is explored on thermal characteristics and wall shear stress profiles.

Large-eddy simulation of the injection timing effects on the dual-fuel spray flame

Large-eddy simulations (LES) coupled with a partially-stirred reactor model and a finite-rate chemistry are carried out to investigate the effects of n-heptane injection timing on the methanol fueled dual-fuel (DF) combustion. Methanol is premixed with air in a constant volume chamber (T=1000 K, ρ=14.8 kg/m3) to form a homogeneous mixture (equivalence ratio ϕm of 0.3). Liquid fuel n-heptane is provided from a high pressure injector to mimic the pilot fuel injection in DF engines. First, mesh sensitivity analysis and LES model validation are conducted. The experimental data of Spray-H (n-heptane fueled) from the Engine Combustion Network is used for model validation. It is shown that the present mesh and LES model are capable of replicating the liquid and vapor penetration length, mixture fraction, temperature distribution, pressure rise profile and ignition delay time (IDT). Second, the effects of n-heptane injection timing are investigated, by varying the start of injection (SOI) time. The LES results reveal that there are three stage heat releases in the DF combustion. With the delay of SOI, the mass fraction of hydrogen peroxide in the ambient mixture increases, leading to an early formation of hydroxyl. Therefore, the two-stage IDTs of n-heptane decrease, while the ambient methanol IDT increases. Results also show the cool flame and high-temperature flame evolution after methanol auto-ignition. The cool flame disappears while the high-temperature flame is found near the injector nozzle, which leads to a relatively high heat release rate.

Research of the mechanisms of penetration of toxic chemicals through a multilayer composite sorption-active material

The mechanism of penetration of liquid and vapors of a simulator of toxic chemicals through samples of multilayer sorptionactive materials obtained by the method of double-sided duplication, differing in different structure and composition, has been determined.The optimal structure of a multilayer composite sorption-active material has been selected for the manufacture of personal protective equipment for the skin of a filtering type, which provides high hygienic and protective properties as close as possible to materials of an insulating type, as well as a technology for its production.

Liquid-Assisted Single-Layer Janus Membrane for Efficient Unidirectional Liquid Penetration.

Unidirectional liquid penetration plays an important role in many fields, such as microfluidic devices, biological medical, liquid printing, and oil/water separation. Although there are some progresses in the liquid unidirectional penetration using a variety of Janus membranes with anisotropic wettability, it still remains a great difficulty for single‐layer Janus membranes with straight pore to balance spontaneous liquid penetration in positive direction and superior liquid resistance in the reverse direction. Herein, a liquid‐assisted strategy for single‐layer Janus membrane is developed, which can efficiently decrease the critical breakthrough pressure from superhydrophobic side to hydrophilic side and show little influence on that in the reverse direction. Consequently, unidirectional water penetration with high hydraulic pressure difference can be achieved. The Laplace pressure change along the thickness of the single‐layer Janus membranes is further discussed, and the mechanism by which the auxiliary liquid decreases the critical breakthrough pressure is revealed. Furthermore, this Janus membrane with unidirectional water penetration “diode” performance can be used to prevent liquid backflow in intravenous transfusion. It is believed that this work can open an avenue for people to design single‐layer Janus membrane with high pressure difference and find wide applications in unidirectional liquid transport.

Large-Eddy Simulation of Laser-Ignited Direct Injection Gasoline Spray for Emission Control

Large-Eddy Simulations (LES) of a gasoline spray, where the mixture was ignited rapidly during or after injection, were performed in comparison to a previous experimental study with quantitative flame motion and soot formation data [SAE 2020-01-0291] and an accompanying Reynolds-Averaged Navier–Stokes (RANS) simulation at the same conditions. The present study reveals major shortcomings in common RANS combustion modeling practices that are significantly improved using LES at the conditions of the study, specifically for the phenomenon of rapid ignition in the highly turbulent, stratified mixture. At different ignition timings, benchmarks for the study include spray mixing and evaporation, flame propagation after ignition, and soot formation in rich mixtures. A comparison of the simulations and the experiments showed that the LES with Dynamic Structure turbulence were able to capture correctly the liquid penetration length, and to some extent, spray collapse demonstrated in the experiments. For early and intermediate ignition timings, the LES showed excellent agreement to the measurements in terms of flame structure, extent of flame penetration, and heat-release rate. However, RANS simulations (employing the common G-equation or well-stirred reactor) showed much too rapid flame spread and heat release, with connections to the predicted turbulent kinetic energy. With confidence in the LES for predicted mixture and flame motion, the predicted soot formation/oxidation was also compared to the experiments. The soot location was well captured in the LES, but the soot mass was largely underestimated using the empirical Hiroyasu model. An analysis of the predicted fuel–air mixture was used to explain different flame propagation speeds and soot production tendencies when varying ignition timing.

69-Year Old Man With Dysphagia and Nasal Regurgitation

69-Year Old Man With Dysphagia and Nasal Regurgitation

The influence of water hardness perturbations on bubble departure dynamics

The influence of small changes to water hardness on the nonlinear behaviour of liquid penetration into a capillary and the resulting air pressure fluctuations during air bubble formation are examined in this paper. Experiments were undertaken in which bubbles were generated both in water having a surface tensile force of σ = 72.2 mN/m and in an aqueous solution of calcium carbonate having a surface tensile force of σ = 75.4 mN/m, each contained in a glass capillary with an internal diameter of 1 mm. It is shown that both the maximum value of liquid penetration into the capillary and bubble growth time are affected by perturbations to the water hardness. The time it takes for the bubble to depart the capillary was estimated using the following nonlinear data analysis methods: time delay (τ), attractor reconstructions, correlation dimension (D), and largest Lyapunov exponent (λ). All estimates demonstrate that the pressure fluctuations in the c–c aqueous solutions and extent of liquid solution penetration into the capillary during the time between subsequent bubble departures behave chaotically. Furthermore, this work demonstrates that the dynamics of bubble formation along with the bubble waiting time are very sensitive to small perturbation in the physical properties of the liquid, and this sensitivity has a significant effect on the observed chaotic behaviour.

Predictive values of static endoscopic evaluation of swallowing in adults.

ObjectiveStatic endoscopic evaluation of swallowing (SEES) is an instrumental evaluation developed for in‐office identification of patients who may benefit from a modified barium swallow study (MBSS). We aim to determine the predictive value of SEES for evaluating dysphagia.MethodsA retrospective case series was performed on adults evaluated for dysphagia using SEES followed by MBSS at a single tertiary care center. Studies were evaluated by two blinded expert raters.ResultsFifty‐eight patients were included. Thin liquid penetration on SEES had a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 0.86 (95% CI 0.70‐0.95), 0.63 (95% CI 0.24‐0.91), 0.91 (95% CI 0.76‐0.98), and 0.5 (0.19‐0.81), respectively, for predicting thin liquid penetration on MBSS, and 1.0 (95% CI 0.59‐1.0), 0.29 (95% CI 0.15‐0.47), 0.23 (95% CI 0.10‐0.41), and 1.0 (95% CI 0.69‐1.0) for predicting thin liquid aspiration on MBSS. Thin liquid aspiration on SEES had a sensitivity, specificity, PPV, and NPV of 0.67 (95% CI 0.09‐0.99), 0.85 (95% CI 0.66‐0.96), 0.33 (95% CI 0.04‐0.78), and 0.96 (95% CI 0.79‐1.0), respectively, for predicting thin liquid aspiration on MBSS.ConclusionsSEES may be used as an objective in‐office test to screen for aspiration and penetration. Thin liquid penetration on SEES is moderately sensitive for predicting penetration on MBSS. Absence of thin liquid penetration or aspiration on SEES has a high NPV for excluding aspiration on MBSS. Abnormalities on SEES or the need to view the entire swallowing mechanism should prompt an MBSS for a more complete evaluation of dysphagia.Level of Evidence: 4

Numerical study of spray combustion and soot emission of gasoline–biodiesel fuel under gasoline compression ignition-relevant conditions

A blend of biodiesel and gasoline fuel has been proposed for powering gasoline compression ignition (GCI) engines to improve overall reactivity, which is essential for the auto-ignition quality of GCI engines. Previous studies emphasized the differences in the physicochemical properties of hydrogenated catalytic biodiesel (HCB) and gasoline, which significantly altered the combustion characteristics. This study is a further step in this direction to gain a deeper understanding on the spray combustion and emission behavior of this promising fuel based on computational fluid dynamic simulation in a constant volume chamber. N-Hexadecane and toluene reference fuel were selected as surrogates for HCB and gasoline fuel, respectively. A reduced kinetic mechanism for HCB-gasoline surrogate was developed and combined with a reduced PAH mechanism to simulate HCB-gasoline spray combustion and soot formation. Liquid penetration length, ignition delay, lift-off length, and soot formation for HCB and HCB/gasoline surrogates were validated against available experimental data in the literature. The proposed mechanism along with a multi-step phenomenological soot model could capture the spray characteristics and soot formation of the tested fuels with acceptable accuracy under GCI engine combustion conditions. The numerical results showed larger spray/flame development for HCB fuel as compared with that of HCB/gasoline blend prior to ignition and at ignition stage, which was mainly due to the less fuel spray mixing with the surrounding fresh air. Furthermore, the outer diffusion flames for HCB and HCB/gasoline blend were identical and existed on the stoichiometric region (at ϕ ∼ 1), while the rich pre-mixed core of HCB was located at higher equivalence ratio, which was more favorable for precursors formation. HCB/gasoline fuel had a lower soot mass yield compared with HCB because of its lower C2H2 concentration, which slowed down the surface growth step. In addition, the effects of ambient oxygen level and ambient temperature on flame structure and soot formation were also investigated. The current study provides a useful information about spray combustion and soot formation of HCB–gasoline blend, which has practical applications in GCI engines.

3D Visualization of Liquid Water Penetration from MPL to Substrate Layer in PEFC Using in-Situ X-Ray Tomographic Microscopy

Polymer electrolyte fuel cells (PEFCs) play an important role in solving environmental problems and energy problems. It is required to perform them at higher current density to achieve the cost reduction. Under the circumstance, however, the cathode gas diffusion layers (GDLs) are saturated with liquid water, which is generated from the electrochemical reaction and condenses. In other words, water is one of the factors that prevents the oxygen diffusion, and clarifying the water management in GDLs is essential to perform at higher current density. At present, synchrotron-based X-ray tomographic microscopy (XTM) is the common way to observe water distribution. While its high intensity makes it possible to get high contrast data by imaging in short exposure time, it decomposes the polymer electrolyte. It is the crucial point to keep cell performance during imaging. In addition, the experiment time using synchrotron radiation facility is limited. To inspect other ways than synchrotron-based XTM, here we aim to achieve 3D visualization of liquid water penetration in GDLs using laboratory-based in-situ XTM. Besides, we aim to evaluate the relationship between water distribution and GDL structure. To get 3D data of liquid water penetration in GDLs using Rigaku nano3DX, which is the laboratory-based X-ray imaging, the fuel cell with an active area 1.0 × 1.0 mm2 was applied. The cell equipped with Toray TGP-H-060 coated with micro porous layer (MPL) was used. 3D data that spatial resolution was 2.16 um was taken. By applying phase retrieval process and image processing, MPL, fiber, water and air were classified. As a result, we have succeeded in the 3D visualization of liquid water penetration from MPL to substrate layer under room temperature. Then, the volume of water captured by XTM was compared with that detected by X-ray radiography to verify that XTM could capture water precisely. This is because some water which is moving during imaging cannot be captured after reconstruction. The total scan time was about 3 hours, which is longer than that of synchrotron-based XTM. It took about 14 second to get an image by X-ray radiography. As a result, though the amount of water near the separator captured by XTM was fewer than that detected by X-ray radiography, the amount of water near MPL and substrate layer was almost the same. The results showed that the liquid water distribution obtained by laboratory-based XTM is reliable. Figure shows 3D images of cathode GDL and water at current density of 0.75, 1.0, 1.25, 1.5 A/cm2. We have identified that water passed through the cracks of MPL and remained in substrate layer where was close to the boundary between MPL and substrate layer. In addition, the effective pore diameter of substrate layer which water remained in was analyzed, and it was identified that water tended to remain in the bigger pore diameter. This is because substrate layer we used is hydrophobic. The result indicates that the existence of cracks on MPL has a strong influence on liquid water distribution and oxygen transport to the catalyst layer. Figure 1

Competitive Wetting: A New Approach to Prevent Liquid Penetration through Porous Materials with Superior Synergistic Effect.

Blocking liquid penetration in porous materials is a key function for several applications including chemical protective clothing (CPC), wound healing, and hygiene products. Enormous efforts are made to prevent liquid penetration through porous media by the modification of materials. CPC is used as an example to demonstrate the effect of the synergistic effect on liquid penetration. A common strategy to achieve liquid protection is the use of liquid-repellent surfaces with the aid of a liquid absorption liner layer. However, this strategy demonstrates limited success for low surface energy liquids. Herein, a novel approach is reported to prevent the permeation of liquid across porous materials by a synergistic effect. Both fabrics are individually susceptible to be wetted by low surface tension liquids. However, when they are assembled, they can prevent low surface tension liquids from penetrating because of the wettability gap between the two fabrics. The fabric assembly demonstrates an increase in the liquid prevention capacity by 70-1000 times compared with a commercial CPC material. This novel synergistic effect may offer a breakthrough in the development of various applications including protective clothing baby nappies, hygiene products, food preparation, soil water retention, and sporting/camping/ski equipment and clothing.

Comparative Evaluation of the Penetration Depth into Dentinal Tubules of Three Endodontic Irrigants.

This study aimed to examine the penetration depth into dentinal tubules of some chelating agents. The 17% EDTA and two preparations containing surfactants (Smear Clear, Bioakt Endo) were tested. Surface tension and liquid viscosity were measured using a Dynamic Contact Angle Analyzer and a Haake rotational rheometer. To measure the penetration depth inside dentinal tubules, thirty maxillary central incisors were selected from a pool of extracted human permanent teeth and allocated to three experimental groups (10 samples each), as well as were mechanically shaped and cleansed with 5.25% NaOCl, followed by each of the chelators being labeled with 0.1 wt % Rhodamine B according to final irrigation protocol established. The samples were embedded in an epoxy resin, after which 200 μm thick transverse sections were obtained at 2, 5, and 8 mm from the apex with a saw microtome. The specimens were then observed using a confocal laser microscope (CLSM) and the penetration of the labeled solution was measured in every third of each sample. Statistical analysis was performed using ANOVA or Kruskal–Wallis tests according to the distribution of data, evaluated with the Shapiro–Wilk normality test. Viscosity and surface tension tests have shown that BioAKT Endo has the lowest values compared to EDTA and Smear Clear. The medium penetration depth did not significantly differ among the three irrigants, while it increased considerably from the apical to the coronal level in all groups. Additionally, the maximum penetration depth increased significantly from the apical to coronal level, while among groups, BioAKT Endo showed the highest values at the apical and middle level compared to the other irrigants. No significant differences were observed among the three groups in medium and maximum penetration depths when the entire root was considered. New irrigants containing surfactants show reduced surface tension and, in one case (BioAKT Endo), viscosity. The lowering of the surface tension allows for better penetration of liquids into dentinal tubules than EDTA alone, thus improving the cleaning of the root canal system.

A zonal secondary break-up model for 3D-CFD simulations of GDI sprays

In Gasoline Direct Injection (GDI) engines, the secondary break-up plays a significant role in air–fuel mixing. In fact, spray granulometry affects evaporation rate, liquid penetration and plume morphology. Operating pressures and temperatures of both liquid and gaseous phases strongly influence the droplet disruption mechanism in the combustion chamber. In 3D Computational Fluid Dynamics (CFD), several models can be adopted to simulate the secondary break-up process, among which the Reitz-Diwakar and the Kelvin-Helmholtz Rayleigh-Taylor (KHRT) are the most diffused ones in the engine community. However, application of such models in their original versions is limited to a reduced range of injection parameters and ambient conditions. As a matter of fact, large variations of them usually require ad-hoc calibrations of the model constants. To improve the predictive capabilities and reduce the need of case-by-case tuning, an alternative secondary break-up model is proposed in the present paper. It is based on the Reitz-Diwakar one but, compared to the latter, a zonalization of the break-up regimes is proposed. Specifically, it is assumed that only Stripping break-up can occur near the nozzle, while Bag break-up only takes place sufficiently far from it. Moreover, model parameters are now treated as functions of the operating conditions. In particular, the impact of the ambient density on the model parameters is analysed in the present work. The proposed model is calibrated via constant volume vessel simulations on a single-hole GDI research injector at vacuum-to-pressurized conditions (namely at 0.4, 1.0, and 3.0 bar(a) of back pressure), on equal temperature. Model parameters are found to be linear functions of the ambient density. Thereafter, model validation is carried out on two different GDI injectors. The first is again a single-hole (remarkably different compared to the previous one), while the second is a 5-hole prototype. Numerical results provided by the proposed model show a satisfactory agreement compared to the experiments in terms of liquid penetration, Phase Doppler Anemometry (PDA) data and imaging, without any dedicated tuning. Conversely, the Reitz-Diwakar and KHRT models, applied to simulate (with default calibration constants) the same injectors, provide results which remarkably deviate from the experiments.