Mechanisms of fuel injector tip wetting and tip drying based on experimental measurements of engine-out particulate emissions from gasoline direct-injection engines

2020 ◽  
pp. 146808742091605 ◽  
Author(s):  
M Medina ◽  
FM Alzahrani ◽  
M Fatouraie ◽  
MS Wooldridge ◽  
V Sick
Keyword(s):  
Conceptual Understanding ◽  
Direct Injection ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Coolant Temperature ◽  
Particulate Emissions ◽  
Fuel Injector ◽  
Wetting And Drying ◽  
Direct Injection Engines ◽  
Particulate Number

Gasoline fuel deposited on the fuel injector tip has been identified as a significant source of particulate emissions at some operating conditions of gasoline direct-injection engines. This work proposes simplified conceptual understanding for mechanisms controlling injector tip wetting and tip drying in gasoline direct-injection engines. The objective of the work was to identify which physical mechanisms of tip wetting and drying were most important for the operating conditions and hardware considered and to relate the mechanisms to measurements of particulate number emissions. Trends for each of the physical processes were evaluated as a function of engine operating conditions such as engine speed, start of injection timing, engine load, fuel rail pressure, and coolant temperature. The effects of fuel injector geometries on the tip wetting and drying mechanisms were also considered. Several mechanisms of injector tip wetting were represented with the conceptual understanding including wide plume wetting, vortex droplet wetting, fuel dribble wetting, and fuel condensation wetting. The main tip drying mechanism considered was single-phase evaporation. Using the conceptual understanding for tip wetting and drying mechanisms that were created in this work, the effects of engine operating conditions and fuel injector geometries on the mechanisms were compared with experimental results for particulate number. The results indicate that measured particulate number was increased by increasing injected fuel mass. Increasing injected fuel mass was suspected to increase tip wetting via wide plume wetting and vortex droplet wetting mechanisms. Particulate number was also observed to increase with hole length. Longer hole length was suspected to result in higher tip wetting via vortex droplet and fuel dribble wetting mechanisms. Longer timescale was found to decrease particulate number emissions. Lower speeds and early injection timings increased the timescale. Similarly, higher coolant temperature decreased particulate number. The coolant temperature influenced tip temperature resulting in higher tip drying.

Analytical model for liquid film evaporation on fuel injector tip for the mitigation of injector tip wetting and the resulting particulate emissions in gasoline direct-injection engines

2020 ◽  
pp. 146808742097389
Author(s):  
Fahad M Alzahrani ◽  
Mohammad Fatouraie ◽  
Volker Sick
Keyword(s):  
Liquid Film ◽  
Analytical Model ◽  
Time Constant ◽  
Direct Injection ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Particulate Emissions ◽  
Fuel Injector ◽  
Direct Injection Engines ◽  
Film Evaporation

Unevaporated fuel films forming on the fuel injector tip of gasoline direct-injection engines burn in a diffusion flame at the time of spark, producing particulates and at some operating conditions, these films have been identified as the dominating source of particulate emissions. This work developed an analytical model for liquid film evaporation on the injector tip, that is, injector tip drying, for the mitigation of injector tip wetting and the resulting particulate emissions. The model explains theoretically how fuel films on the injector tip evaporate with time from the end of injection to the spark. The model takes into consideration engine operating conditions, including engine load and speed, tip and fuel temperatures, gas temperature and pressure, and fuel properties. The model explains the observed trends in particulate number (PN) emissions due to injector tip wetting. Engine experiments were used to validate the model by correlating the predicted film mass at the time of spark to measurements of PN emissions at different conditions. A tip drying time constant was also defined and was found to correlate well with the measured PN for all conditions tested. This time constant is a deterministic factor for mitigating tip wetting. In general, the results indicate that the liquid film evaporation on the injector tip follows a first order, asymptotic behavior. Furthermore, the tip drying physics causes the observed increasing and decreasing non-linear trends in PN emissions with the engine load and the available time for tip drying, respectively. Additionally, the liquid film evaporation on the injector tip is highly sensitive to most of the injector initial and boundary conditions, including the initial film mass after the end of injection, the wetted surface area, the available time for tip drying and the injector tip temperature. The initial film temperature has the least effect on film mass evaporation.

The Research Progress of Particulate Emissions from Vehicles with Gasoline Direct Injection Engines

2013 ◽  
Vol 726-731 ◽  
pp. 2351-2354
Author(s):  
Guang Yang Liu ◽  
Yu Liu ◽  
Jian Xi Pang ◽  
Yan Qin
Keyword(s):  
Direct Injection ◽  
High Sensitivity ◽  
Cold Start ◽  
Gasoline Direct Injection ◽  
Research Progress ◽  
Particulate Emissions ◽  
Number Count ◽  
Direct Injection Engines ◽  
Driving Cycles ◽  
Particulate Number

The objective of this research is to introduce the main gasoline direct injection vehicle particulate emissions characteristics researches in the world. Many investigations of particulate sizing and number count from gasoline direct injection (GDI) vehicles at different driving cycles were performed. Lots of particulate emissions are measured for FTP-75, NEDC, HWTET, SC03, and US06 cycles and these cycles can reflect different aspects of the particulate emissions. In some papers, both engine-out and tailpipe emissions were measured. Some investigation showed high sensitivity of the particulate number or size distribution to changes with the engine control parameters including A/F, ignition timing, EOI and so on.On the whole, the particulate number during different Driving Cycle is shown along with further analysis of the transient particulate emissions. The cold start process obviously affects particulate formation. Even beyond cold start, the particulate number emissions decrease as the test progresses. The results coming from the particulate measurement system sampling directly from the exhaust showed very rapid increases in particulate emissions during engine transients.

Combustion Ionization for Detection of Misfire, Knock, and Sporadic Preignition in a Gasoline Direct Injection Engine

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Samuel Ayad ◽  
Swapnil Sharma ◽  
Rohan Verma ◽  
Naeim Henein
Keyword(s):  
Pressure Transducer ◽  
Direct Injection ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Ion Current ◽  
Fuel Injector ◽  
Direct Injection Engine ◽  
Gasoline Direct Injection Engine ◽  
Spark Plug ◽  
Knock Sensor

Detection of combustion-related phenomena such as misfire, knock, and sporadic preignition is very important for the development of electronic controls needed for the gasoline direct injection engines to meet the production goals in power, fuel economy, and low emissions. This paper applies several types of combustion ionization sensors, and a pressure transducer that directly senses the in-cylinder combustion, and the knock sensor which is an accelerometer that detects the impact of combustion on engine structure vibration. Experimental investigations were conducted on a turbocharged four-cylinder gasoline direct injection engine under operating conditions that produce the above phenomena. One of the cylinders is instrumented with a piezo quartz pressure transducer, MSFI (multi-sensing fuel injector), a stand-alone ion current probe, and a spark plug applied to act as an ion current sensor. A comparison is made between the capabilities of the pressure transducer, ion current sensors, and the knock sensor in detecting the above phenomena. The signals from in-cylinder combustion sensors give more accurate information about combustion than the knock sensor. As far as the feasibility and cost of their application in production vehicles, the spark plug sensor and MSFI appear to be the most favorable, followed by the stand-alone mounted sensor which is an addition to the engine.

Modeling of Internal and Near-Nozzle Flow for a Gasoline Direct Injection Fuel Injector

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Kaushik Saha ◽  
Sibendu Som ◽  
Michele Battistoni ◽  
Yanheng Li ◽  
Shaoping Quan ◽  
...  
Keyword(s):  
Liquid Fuel ◽  
Numerical Study ◽  
Direct Injection ◽  
Computational Cost ◽  
Volume Averaging ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Superheated Liquid ◽  
Fuel Injector ◽  
Flash Boiling

A numerical study of two-phase flow inside the nozzle holes and the issuing spray jets for a multihole direct injection gasoline injector has been presented in this work. The injector geometry is representative of the Spray G nozzle, an eight-hole counterbore injector, from the engine combustion network (ECN). Simulations have been carried out for a fixed needle lift. The effects of turbulence, compressibility, and noncondensable gases have been considered in this work. Standard k–ε turbulence model has been used to model the turbulence. Homogeneous relaxation model (HRM) coupled with volume of fluid (VOF) approach has been utilized to capture the phase-change phenomena inside and outside the injector nozzle. Three different boundary conditions for the outlet domain have been imposed to examine nonflashing and evaporative, nonflashing and nonevaporative, and flashing conditions. Noticeable hole-to-hole variations have been observed in terms of mass flow rates for all the holes under all the operating conditions considered in this study. Inside the nozzle holes mild cavitationlike and in the near-nozzle region flash-boiling phenomena have been predicted when liquid fuel is subjected to superheated ambiance. Under favorable conditions, considerable flashing has been observed in the near-nozzle regions. An enormous volume is occupied by the gasoline vapor, formed by the flash boiling of superheated liquid fuel. Large outlet domain connecting the exits of the holes and the pressure outlet boundary appeared to be necessary leading to substantial computational cost. Volume-averaging instead of mass-averaging is observed to be more effective, especially for finer mesh resolutions.

Multi Sensing Fuel Injector in Turbocharged Gasoline Direct Injection Engines

2013 ◽  
Author(s):  
Fadi Estefanous ◽  
Shenouda Mekhael ◽  
Tamer Badawy ◽  
Naeim Henein ◽  
Akram Zahdeh
Keyword(s):  
Combustion Engine ◽  
Direct Injection ◽  
Electric Circuit ◽  
Life Time ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Feedback Signal ◽  
Injection Timing ◽  
Fuel Injector ◽  
Spark Plug

With the increasingly stringent emissions and fuel economy standards, there is a need to develop new advanced in-cylinder sensing techniques to optimize the operation of internal combustion engine. In addition, reducing the number of on-board sensors needed for proper engine monitoring over the life time of the vehicle would reduce the cost and complexity of the electronic system. This paper presents a new technique to enable one engine component, the fuel injector, to perform multiple sensing tasks in addition to its primary task of delivering the fuel into the cylinder. The injector is instrumented within an electric circuit to produce a signal indicative of some injection and combustion parameters in electronically controlled spark ignition direct injection (SIDI) engines. The output of the multi sensing fuel injector (MSFI) system can be used as a feedback signal to the engine control unit (ECU) for injection timing control and diagnosis of the injection and combustion processes. A comparison between sensing capabilities of the multi-sensing fuel injector and the spark plug-ion sensor under different engine operating conditions is also included in this study. In addition, the combined use of the ion current signals produced by the MSFI and the spark plug for combustion sensing and control is demonstrated.

Multisensing Fuel Injector in Turbocharged Gasoline Direct Injection Engines

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Fadi Estefanous ◽  
Shenouda Mekhael ◽  
Tamer Badawy ◽  
Naeim Henein ◽  
Akram Zahdeh
Keyword(s):  
Combustion Engine ◽  
Direct Injection ◽  
Control Unit ◽  
Electric Circuit ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Feedback Signal ◽  
Injection Timing ◽  
Fuel Injector ◽  
Spark Plug

With the increasingly stringent emissions and fuel economy standards, there is a need to develop new advanced in-cylinder sensing techniques to optimize the operation of the internal combustion engine. In addition, reducing the number of on-board sensors needed for proper engine monitoring over the lifetime of the vehicle would reduce the cost and complexity of the electronic system. This paper presents a new technique to enable one engine component, the fuel injector, to perform multiple sensing tasks in addition to its primary task of delivering the fuel into the cylinder. The injector is instrumented within an electric circuit to produce a signal indicative of some injection and combustion parameters in electronically controlled spark ignition direct injection (SIDI) engines. The output of the multisensing fuel injector (MSFI) system can be used as a feedback signal to the engine control unit (ECU) for injection timing control and diagnosis of the injection and combustion processes. A comparison between sensing capabilities of the multisensing fuel injector and the spark plug-ion sensor under different engine operating conditions is also included in this study. In addition, the combined use of the ion current signals produced by the MSFI and the spark plug for combustion sensing and control is demonstrated.

Combustion Ionization for Detection of Misfire, Knock, and Sporadic Pre-Ignition in a Gasoline Direct Injection Engine

2018 ◽  
Author(s):  
Samuel Ayad ◽  
Swapnil Sharma ◽  
Rohan Verma ◽  
Naeim Henein
Keyword(s):  
Pressure Transducer ◽  
Direct Injection ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Ion Current ◽  
Fuel Injector ◽  
Direct Injection Engine ◽  
Gasoline Direct Injection Engine ◽  
Spark Plug ◽  
Knock Sensor

Detection of combustion related phenomena such as misfire, knock and sporadic preignition is very important for the development of electronic controls needed for the gasoline direct injection engines to meet the production goals in power, fuel economy, and low emissions. This paper applies several types of combustion ionization sensors, and a pressure transducer that directly sense the in-cylinder combustion, and the knock sensor which is an accelerometer that detects the impact of combustion on engine structure vibration. Experimental investigations were conducted on a turbocharged four cylinders gasoline direct injection engine under operating conditions that produce the above phenomena. One of the cylinders is instrumented with a Piezo quartz pressure transducer, MSFI (Multi sensing fuel injector), a standalone ion current probe, and a spark plug applied to act as an ion current sensor. A comparison is made between the capabilities of the pressure transducer, ion current sensors, and the knock sensor in detecting the above phenomena. The signals from in-cylinder combustion sensors give more accurate information about combustion than the knock sensor. As far as the feasibility and cost of their application in production vehicles the spark plug sensor and MSFI appear to be the most favorable, followed by the Standalone mounted sensor which is an addition to the engine.

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