Pressure-Swirl Atomization in the Near Field

Schmidt, David P.; Nouar, Idriss; Senecal, P. K.; Rutland, Christopher J.; Martin, Jay K.; Reitz, Rolf D.; Hoffman, Jeffrey A.

doi:10.4271/1999-01-0496

Cited by 154 publications

(85 citation statements)

References 18 publications

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“…(1), and a correlation for the coefficient has been suggested [36]. Later, Schmidt et al [37] estimated the velocity coefficient from a typical value (0.78) of the discharge coefficient of a single nozzle with sharp inlet corners by reducing the value by 10% for extra momentum losses, such that (2) where θ is the half of spray angle and d n is the nozzle diameter. This velocity coefficient agrees with the definition of the discharge coefficient.…”

Section: Numerical Setupmentioning

confidence: 99%

“…Therefore, the nozzle's discharge coefficient (C D ) of 0.7 is used for the injection velocity calculation in the present outwardly opening hollow-cone spray simulations. From Schmidt et al [37], the initial sheet thickness of the liquid film (t 0 ) can be obtained from the known mass flow rate (ṁ) and the injection velocity (U) by (3) The calculated liquid sheet thickness is a starting point in our spray modeling regardless of breakup or collision models. In the present study, modified KH-RT is implemented.…”

Section: Numerical Setupmentioning

confidence: 99%

See 1 more Smart Citation

Effects of In-Cylinder Mixing on Low Octane Gasoline Compression Ignition Combustion

Badra

Elwardany

Sim

et al. 2016

SAE Technical Paper Series

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Gasoline compression ignition (GCI) engines have been considered an attractive alternative to traditional spark ignition engines. Low octane gasoline fuel has been identified as a viable option for the GCI engine applications due to its longer ignition delay characteristics compared to diesel and in the volatility range of gasoline fuels. In this study, we have investigated the effect of different injection timings at part-load conditions using light naphtha stream in single cylinder engine experiments in the GCI combustion mode with injection pressure of 130 bar. A toluene primary reference fuel (TPRF) was used as a surrogate for the light naphtha in the engine simulations performed here. A physical surrogate based on the evaporation characteristics of the light naphtha has been developed and its properties have been implemented in the engine simulations. Full cycle GCI computational fluid dynamics (CFD) engine simulations have been successfully performed while changing the start of injection (SOI) timing from -50° to -11 ° CAD aTDC. The effect of SOI on mixing and combustion phasing was investigated using detailed equivalence ratio-temperature maps and ignition delay times. Both experimental and computational results consistently showed that an SOI of -30° CAD aTDC has the most advanced combustion phasing (CA50), with the highest NOx emission. The effects of the SOI on the fuel containment in the bowl of the piston, the ignition delay time, combustion rate and emissions have been carefully examined through the CFD calculations. It was found that the competition between the equivalence ratio and temperature is the controlling parameter in determining the combustion phasings.

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Section: Numerical Setupmentioning

confidence: 99%

Section: Numerical Setupmentioning

confidence: 99%

Effects of In-Cylinder Mixing on Low Octane Gasoline Compression Ignition Combustion

Badra

Elwardany

Sim

et al. 2016

SAE Technical Paper Series

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“…This is a common approximation made in phenomenological modeling of atomizers in cases where only one flow velocity scale is available (Lefebvre 1989;Razzaghi 1989;Schmidt et al 1999;Senecal et al 1999). …”

Section: Mathematical Formulationmentioning

confidence: 99%

Transient aerodynamic atomization model to predict aerosol droplet size of pressurized metered dose inhalers (pMDI)

Gavtash

Versteeg

Hargrave

et al. 2017

Aerosol Science and Technology

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Pressurized metered dose inhalers (pMDI) produce large numbers of droplets with smaller sizes than 5 mm to treat asthma and other pulmonary diseases. The mechanism responsible for droplet generation from bulk propellant liquid is poorly understood, mainly because the small length scales and short time scales make it difficult to characterize transient spray formation events. This article describes the development and findings of a numerical atomization model to predict droplet size of pharmaceutical propellants from first principles. In this model, the velocity difference between propellant vapor and liquid phase inside spray orifice leads to formation of wave-like instabilities on the liquid surface. Two variants of the aerodynamic atomization model are presented based on assumed liquid precursor geometry: (1) cylindrical jet-shaped liquid ligaments surrounded by vapor annulus; (2) annular liquid film with vapor flow in the core. The growth of instabilities on the liquid precursor surfaces and the size of the subsequently formed droplets are predicted by numerical solutions of dispersion equations. The droplet size predictions were compared with phase doppler anemometry (PDA) data and the predictions were in good agreement with the number mean diameter D 10 , which is representative of the respirable droplets. The temporal behavior of droplet size production was captured consistently well during the period of the first 95% of the propellant mass emission. The outcome of our modeling activities also suggests that, in addition to saturated vapor pressure of the propellant, its viscosity and surface tension are also key properties that govern pMDI droplet size. EDITORWarren Finlay

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“…Pressure-swirling and inwardly-opening hollow-cone spray injector has been commonly utilized in GDI and GCI engines due to its efficient atomization with relatively wide spray angle and fine atomization [6,7,8]. Recently, the outwardly-opening piezoelectric injector is gaining popularity as a high efficient hollow-cone spray injector due to its precise control of the spray by accurate piezoelectric actuator [9].…”

Section: Introductionmentioning

confidence: 99%

“…It has been known that the typical KelvinHelmholtz and Rayleigh-Taylor (KH-RT) breakup model is unable to describe the hollow-cone spray because the liquid is injected with circular-shaped liquid sheet instead of a cylindrical blob. As such, Schmidt et al [7] proposed the linear instability sheet atomization (LISA) model by assuming toroidal ligament breakup for pressureswirl hollow-cone spray injectors, where the Taylor analogy breakup (TAB) was used as a secondary breakup model after primary LISA breakup. The LISA-TAB model was further applied to the outwardlyopening injector by assuming slug flow, although linear instability theory was unable to model the actual breakups of expanding 3-D liquid sheets [8].…”

Section: Introductionmentioning

confidence: 99%