A computational approach to predict external spray characteristics for flashing and cavitating nozzles

Rachakonda, Sampath K.; Wang, Yue; Grover, Ronald O.; Moulai, Maryam; Baldwin, E.; Zhang, Gaoming; Parrish, Scott; Diwakar, Ramachandra; Kuo, Tang-Wei; Schmidt, David P.

doi:10.1016/j.ijmultiphaseflow.2018.04.012

Cited by 23 publications

(8 citation statements)

References 23 publications

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“…The two-phase solver has been validated on several previous occasions. 34–37,42 An experimental condition tested by Lacey et al 20 using the standard eight-hole ECN Spray G injector was simulated under both fixed needle lift and needle motion conditions. Contrary to the simulations presented in the proceeding sections of this manuscript, the validation and verification were carried out on the full geometry without using a symmetry plane.…”

Section: Resultsmentioning

confidence: 99%

“…41 The solver was initially implemented by Schmidt et al 33 and has since been subjected to improvements. 35,37,38,42 The current description focuses on the implementation of a diffuse-interface approach to model phase change and primary atomization.…”

Section: Governing Equationsmentioning

confidence: 99%

“…Since its initial development by Vallet et al, 45 the area-interface-density model has been subjected to many improvements and validation studies in the context of diesel sprays 30–32,46 and recently in the case of gasoline sprays. 42,47…”

Section: Governing Equationsmentioning

confidence: 99%

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Prediction of spray collapse in multi-hole gasoline direct-injection fuel injectors

Rachakonda

Paydarfar

Schmidt

2018

International Journal of Engine Research

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A parametric study was conducted to predict the conditions leading to spray collapse in multi-hole gasoline direct-injection fuel injectors using computational fluid dynamics simulations. The computational fluid dynamics simulations were performed using an in-house multi-dimensional code that accounts for thermal non-equilibrium and entrainment of the non-condensable gas and coupled with primary atomization. The simulations were performed for a fixed injection pressure and fuel temperature on nine different six-hole injectors. The parameters were varied to include the effects of the ratio of the ambient pressure to the saturation pressure (Pa/Ps), the drill angle, and the diameters of the nozzle and the counter bore, respectively, on the spray. The findings indicate that spray collapse results from a combination of the nozzle geometry, the thermodynamic conditions of the fuel, and the ambient pressure. Spray collapse was observed in injectors with a narrow arrangement of the nozzle holes under extreme flash-boiling conditions with very low ambient pressures and in the case of non-flash-boiling conditions with very high ambient pressures.

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Section: Resultsmentioning

confidence: 99%

Section: Governing Equationsmentioning

confidence: 99%

See 1 more Smart Citation

Prediction of spray collapse in multi-hole gasoline direct-injection fuel injectors

Rachakonda

Paydarfar

Schmidt

2018

International Journal of Engine Research

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“…It is difficult to reform the invisible drops in imaging results, but by applying optical methodology, it is possible to post process the CFD data to match with the imaged results. Attempts have been made to correct spray angle simulations with backlit imaging data based on Beer-Lambert law [5], and the results have been proved to be helpful for model refinements, but due to the theory difference, such refinement is not proper for Mie-scattering based experiments, which are also widely used in spray detecting. In this research, efforts are made to post-process the CFD data via Mie-scattering theory, and make it 'apple to apple' with experimental images, so as to achieve effective calibration for following studies.…”

Section: Introductionmentioning

confidence: 99%

Post Processing Method for Lagrangian Spray Field Based on Mie Scattering Theory

Wang

Cao

Yang

et al. 2021

ICLASS

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Numerical simulation and experiment are regarded as the two major methods in the investigation of spray and atomization. Simulation methods major in predicting spray developments, whose model are supposed to be calibrated using corresponding experimental data, but direct comparisons between simulation data and experimental results might lead to confusion when focusing on spray boundaries or penetration, as the light scattering physics during imaging is always likely to be ignored in CFD post processing. In many cases, CFD provides data points that are invisible to human eyes or cameras, resulting in variance in boundary confirming process. Previous studies discussed backlit conditions in Euler-based simulations to identify spray boundaries, but for most commonly used Lagrangian-based simulations, this topic remains undiscussed. In Lagrangian-based methods, droplets are treated as discrete particles, where scattering plays a more crucial role compared with that in Euler fields. In this study, light intensity analysis based on Mie Scattering theory and intensity integration focusing on Lagrangian field has been presented, aiming to present simulation data of spray coincides with Mie Scattering image as much as possible. It is found that particle size and in parcel numbers are related with the scattering intensity of droplet particles, and the calibrated CFD data using Mie-Scattering theory shows a better coherence with Mie Scattering imaging results in tested conditions compared with raw simulation data, and this variance tends to be greater when spray density difference is apparent.

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“…Researchers have also taken a computational approach to comprehend flash boiling. Rachakonda et al 14 predicted and validated the external spray characteristics for flash boiling and cavitating nozzle using an Eulerian computational fluid dynamics (CFD) solver which simulates internal nozzle flows and external spray. Yang et al 15 focused on the optical investigation of multi-component flash boiling using near-field high-speed imaging.…”

Section: Introductionmentioning

confidence: 99%

Effects of nozzle hole configuration of a multi-hole type gasoline direct injector on spray development under flash boiling conditions

Kim

Park

2020

International Journal of Engine Research

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The flash boiling phenomenon is critically affected by not only injection conditions such as fuel temperature, ambient pressure and physical properties of fuel but also the nozzle hole configurations of the injector. In this research, two kinds of injectors, having different nozzle hole configurations (a closed type and a opened type) were used to analyze the influence of flash boiling. Near-field and far-field spray visualization was performed using a high-speed camera based on the Mie-scattering imaging technique. Test parameters were injection pressure, ambient pressure, and fuel temperature. The spray length, spray width, length-to-width ratio, and axial velocity of spray development depending on time were measured using the MATLAB program for quantitative and objective analysis. Finally, the prediction equation for the spray length was derived using the least-squares method based on the experimental results. In the case of the closed type injector, the spray center contained a wide overlapped region because of the strong links between plumes. On the other hand, with the opened type injector, there was a relatively narrow overlapped region between plumes due to weak interaction between plumes. As a result, the closed type injector had a narrow and long spray structure and the opened type injector had a partially long and wide spray structure. According to the prediction equation, the spray develops depending on time more linearly under flash boiling conditions than under non-flash boiling conditions. The influence of flash boiling was smaller in the closed type injector because the closed type injector has less variation of the spray structure with varying injection conditions, ranging from non-flash boiling conditions to non-flash boiling conditions.

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A computational approach to predict external spray characteristics for flashing and cavitating nozzles

Cited by 23 publications

References 23 publications

Prediction of spray collapse in multi-hole gasoline direct-injection fuel injectors

Prediction of spray collapse in multi-hole gasoline direct-injection fuel injectors

Post Processing Method for Lagrangian Spray Field Based on Mie Scattering Theory

Effects of nozzle hole configuration of a multi-hole type gasoline direct injector on spray development under flash boiling conditions

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