Phenomenological models of the transient processes of diesel spray tip penetration

Multiple-injection strategy that has been applied widely in diesel engines usually features a short duration for each injection pulse. As a result, the shortened injection makes the needle opening and closing transients increasingly important for spray in an injection event. Owing to the needle movement, the spray development during the transient processes is complex and quite different from the spray at the quasi-steady state. However, so far modeling of the spray development during the transient processes is far from adequate. Particularly, a theoretical zero-dimensional (0-D) spray tip penetration model considering the needle opening and sac pressurization processes as well as ambient and injection conditions during the start-of-injection (SOI) transients is still absent. In this paper, considering the sac pressurization processes, the 0-D model of spray tip penetration during the SOI transients is derived. Then, the model is validated against the experimental spray data using a long-distance microscope together with an ultrahigh speed CMOS camera. The model and experimental results show that the spray tip penetration shows a t3/2 dependence at the initial stage of injection rather than the t dependence suggested by Hiroyasu’s model. Later, the spray tip penetration shows a t3/4 dependence owing to the spray breakup, and a t1/2 dependence with the completion of sac pressurization. The models and analysis are believed to provide new insights into the transient spray behaviors and valuable reference for engineers and researchers who are considering the model-based development of next-generation diesel engines.

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Quasi-Dimensional Diesel Engine Combustion Modeling With Improved Diesel Spray Tip Penetration, Ignition Delay, and Heat Release Submodels

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4036575 ◽

2017 ◽

Vol 139 (11) ◽

Cited By ~ 2

Author(s):

Shuonan Xu ◽

Hirotaka Yamakawa ◽

Keiya Nishida ◽

Zoran Filipi

Keyword(s):

Diesel Engine ◽

Heat Release ◽

Diesel Engines ◽

Ignition Delay ◽

Air Entrainment ◽

Oxygen Mixture ◽

Diesel Spray ◽

Spray Tip Penetration ◽

Simulation Tools ◽

The Impact

Increasingly stringent fuel economy and CO2 emission regulations provide a strong impetus for development of high-efficiency engine technologies. Diesel engines dominate the heavy duty market and significant segments of the global light duty market due to their intrinsically higher thermal efficiency compared to spark-ignited (SI) engine counterparts. Predictive simulation tools can significantly reduce the time and cost associated with optimization of engine injection strategies, and enable investigation over a broad operating space unconstrained by availability of prototype hardware. In comparison with 0D/1D and 3D simulations, Quasi-Dimensional (quasi-D) models offer a balance between predictiveness and computational effort, thus making them very suitable for enhancing the fidelity of engine system simulation tools. A most widely used approach for diesel engine applications is a multizone spray and combustion model pioneered by Hiroyasu and his group. It divides diesel spray into packets and tracks fuel evaporation, air entrainment, gas properties, and ignition delay (induction time) individually during the injection and combustion event. However, original submodels are not well suited for modern diesel engines, and the main objective of this work is to develop a multizonal simulation capable of capturing the impact of high-injection pressures and exhaust gas recirculation (EGR). In particular, a new spray tip penetration submodel is developed based on measurements obtained in a high-pressure, high-temperature constant volume combustion vessel for pressures as high as 1450 bar. Next, ignition delay correlation is modified to capture the effect of reduced oxygen concentration in engines with EGR, and an algorithm considering the chemical reaction rate of hydrocarbon–oxygen mixture improves prediction of the heat release rates. Spray and combustion predictions were validated with experiments on a single-cylinder diesel engine with common rail fuel injection, charge boosting, and EGR.

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CFD simulations of diesel spray tip penetration with multiple injections and with engine compression ratios up to 100:1

Fuel ◽

10.1016/j.fuel.2013.04.058 ◽

2013 ◽

Vol 111 ◽

pp. 289-297 ◽

Cited By ~ 24

Author(s):

Choong Hoon Lee ◽

Rolf D. Reitz

Keyword(s):

Diesel Spray ◽

Cfd Simulations ◽

Spray Tip Penetration ◽

Multiple Injections

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Quasi-D Diesel Engine Combustion Modeling With Improved Diesel Spray Tip Penetration, Ignition Delay and Heat Release Sub-Models

ASME 2016 Internal Combustion Engine Fall Technical Conference ◽

10.1115/icef2016-9403 ◽

2016 ◽

Author(s):

Shuonan Xu ◽

Hirotaka Yamakawa ◽

Keiya Nishida ◽

Zoran Filipi

Keyword(s):

Diesel Engine ◽

Heat Release ◽

Diesel Engines ◽

Ignition Delay ◽

Air Entrainment ◽

Oxygen Mixture ◽

Diesel Spray ◽

Spray Tip Penetration ◽

Simulation Tools ◽

The Impact

Increasingly stringent fuel economy and CO2 emission regulations provide a strong impetus for development of high efficiency engine technologies. Diesel engines dominate the heavy duty market and significant segments of the global light duty market due to their intrinsically higher thermal efficiency compared to spark ignited (SI) engine counterparts. Predictive simulation tools can significantly reduce the time and cost associated with optimization of engine injection strategies, and enable investigation over a broad operating space unconstrained by availability of prototype hardware. In comparison with 0-D/1-D and 3-D simulations, Quasi-D models offer a balance between predictiveness and computational effort, thus making them very suitable for enhancing the fidelity of engine system simulation tools. A most widely used approach for diesel engine applications is a multi-zone spray and combustion model pioneered by Hiroyasu and his group. It divides diesel spray into packets and tracks fuel evaporation, air entrainment, gas properties and ignition delay (induction time) individually during the injection and combustion event. However, original sub-models are not well suited for modern diesel engines, and the main objective of this work is to develop a multi-zonal simulation capable of capturing the impact of high-injection pressures and Exhaust Gas Recirculation (EGR). In particular, a new spray tip penetration sub-model is developed based on measurements obtained in a high-pressure, high-temperature constant volume combustion vessel for pressures as high as 1450 bar. Next, ignition delay correlation is modified to capture the effect of reduced oxygen concentration in engines with EGR, and an algorithm considering the chemical reaction rate of hydrocarbon-oxygen mixture improves prediction of the heat release rates. Spray and combustion predictions were validated with experiments on a single-cylinder diesel engine with common rail fuel injection, charge boosting, and EGR.

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Spray Tip Penetration of Inversed-delta Injection Rate Shaping in Non-Vapourising Condition

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.16.3.2019.16.0528 ◽

2019 ◽

Vol 16 (3) ◽

pp. 7048-7060

Author(s):

M. F. E. Abdullah ◽

Y. Toyama ◽

S. Saruwatari ◽

S. Akiyama ◽

T. Shimada ◽

...

Keyword(s):

High Speed ◽

Injection Pressure ◽

Injection Rate ◽

Diesel Spray ◽

Spray Tip Penetration ◽

Mems Sensor ◽

Fuel Delivery ◽

Rate Shaping ◽

Constant Volume Combustion Chamber ◽

Performance And Emissions

The performance and emissions of diesel engine are highly depending on the fuel delivery process thus, injection rate shaping approach is expected to be crucial in the development of a highly efficient and clean modern engine. A novel rate shaping injector called TAIZAC (TAndem Injection Zapping ACtivation) is used to realise an injection rate shaping of progressive ramp-down of high initial injection pressure as in inversed-delta shape. This study aims to investigate diesel spray tip penetration behaviour in inverseddelta injection rate shaping. The experiments are conducted under a high-density nonvapourising condition in a constant volume combustion chamber. High-speed diffused back illumination DBI imaging of the diesel spray is acquired at 30,000 fps using mercury lamp as the light source. The tip penetration of the inversed-delta injection is smaller than that of rectangle injection regardless of their injection momentum which is proportional to t0.5 and t0.43 in rectangle and inversed-delta injection case, respectively. To examine the potential of inversed-delta injection on wall heat loss reduction, diesel spray flame impinges to a MEMS sensor located at 28-mm downstream. It is interesting to note that the heat flux in 200 MPa inversed-delta injection is reduced by approximately 15% compared to 200 MPa rectangle injection even though their tip penetration starts to diverge at approximately 30 mm; indicates the TAIZAC injector potential in improving engine thermal efficiency.

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