scholarly journals Study of the soot quantification for two-stage injection of hydrogenated catalytic biodiesel in a constant-volume combustion chamber

2017 ◽  
Author(s):  
Cao Jiawei ◽  
He Zhixia ◽  
Li Bei ◽  
Zhong Wenjun ◽  
Wang Mei
Keyword(s):  
High Speed ◽  
Dwell Time ◽  
Pilot Injection ◽  
Two Stage ◽  
Injection Duration ◽  
Soot Mass ◽  
Constant Volume Combustion Chamber ◽  
Main Injection ◽  
Ambient Gas ◽  
Injection Strategies

The effect of two-stage injection strategies on the soot formation of 0# fossil diesel were investigated experimentally using a constant volume combustion chamber. The ambient conditions was kept constant as injection pressure 150 MPa, ambient gas temperature 900 K, ambient gas pressure 45 bar. A high-speed diffused back-illumination extinction imaging technique was employed to make quantitative measurement on temporal soot evolution and reacting spray liquid length and a direct high-speed camera was used to measure the ignition delay. Two-stage injection strategies were varied with different pilot and main injection time, including a sweep of dwell time in pilot-main injection and pilot injection duration. The results show that the ignition delay decreases with the increasing dwell time. It may result from the entrained surrounding gas enhance the spray combustion process. In the reacting condition, the liquid-phase penetration is slightly longer with the shorter dwell time. However, the pilot injection duration shows slighter impact. The longer dwell time contributes to more total soot mass while the different pilot injection duration barely affect the total soot mass of the main injection.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4739

scholarly journals Optical study on characteristics of non-reacting and reacting diesel spray with different strategies of split injection

2018 ◽  
Vol 20 (6) ◽  
pp. 606-623 ◽  
Author(s):  
Jose M Desantes ◽  
José M García-Oliver ◽  
Antonio García ◽  
Tiemin Xuan
Keyword(s):  
High Speed ◽  
Dwell Time ◽  
Soot Formation ◽  
Operating Conditions ◽  
Split Injection ◽  
Injection Duration ◽  
Soot Mass ◽  
Lift Off ◽  
Combustion Processes ◽  
Injection Strategies

Even though studies on split-injection strategies have been published in recent years, there are still many remaining questions about how the first injection affects the mixing and combustion processes of the second one by changing the dwell time between both injection events or by the first injection quantity. In this article, split-injection diesel sprays with different injection strategies are investigated. Visualization of n-dodecane sprays was carried out under both non-reacting and reacting operating conditions in an optically accessible two-stroke engine equipped with a single-hole diesel injector. High-speed Schlieren imaging was applied to visualize the spray geometry development, while diffused background-illumination extinction imaging was applied to quantify the instantaneous soot production (net result of soot formation and oxidation). For non-reacting conditions, it was found that the vapor phase of second injection penetrates faster with a shorter dwell time and independently of the duration of the first injection. This could be explained in terms of one-dimensional spray model results, which provided information on the local mixing and momentum state within the flow. Under reacting conditions, interaction between the second injection and combustion recession of the first injection is observed, resulting in shorter ignition delay and lift-off compared to the first injection. However, soot production behaves differently with different injection strategies. The maximum instantaneous soot mass produced by the second injection increases with a shorter dwell time and with longer first injection duration.

Effect of Pilot Injection on Diesel Knock in a Small-Bore Optical Engine

2012 ◽  
Author(s):  
Alvin M. Rusly ◽  
Sanghoon Kook ◽  
Evatt R. Hawkes ◽  
Renlin Zhang
Keyword(s):  
High Speed ◽  
Pressure Rise ◽  
Pilot Injection ◽  
Cylinder Pressure ◽  
High Speed Imaging ◽  
Term Operation ◽  
Optical Engine ◽  
Injection Duration ◽  
Rise Rate ◽  
Main Injection

Diesel knock is a phenomenon that generates undesirable noise and vibration that can be destructive to diesel engine structures and components for long-term operation. The diesel knock occurs when a large quantity of air-fuel is mixed prior to combustion when the ignition delay is long. This leads to a drastic pressure rise during the premixed phase of the combustion, which is followed by a pressure ringing. The main focus of this study is to examine effect of pilot injection on the pressure ringing and associated in-cylinder flame behaviour. In a single-cylinder small-bore optical engine, in-cylinder pressure measurement and high-speed imaging of the natural combustion luminosity have been performed. Results demonstrate that pilot injection helps reduce the in-cylinder pressure ringing by reducing the pressure rise rate of the main injection. Moreover, oscillation of the flames observed during the knocking events appears to diminish when the pilot injection is applied. How the pilot injection duration and timing affect the diesel knock behaviour is also discussed in detail.

Numerical investigation on the impact of multiple injection strategies and spray included angles on combustion and emissions in a marine diesel engine

2021 ◽  
pp. 095440702110694
Author(s):  
Shiru Kong ◽  
Changpu Zhao ◽  
Zhishang Bian ◽  
Yujie Cai
Keyword(s):  
Injection Timing ◽  
Pilot Injection ◽  
Post Injection ◽  
Simultaneous Reduction ◽  
Included Angle ◽  
Injection Duration ◽  
Marine Diesel ◽  
Main Injection ◽  
The Impact ◽  
Injection Strategies

The computational fluid dynamical software AVL-FIRE code was used for investigating the impact of multiply injection strategies and spray included angles on combustion and emissions in a marine diesel engine. The fuel injection parameters of spray included angle and pilot injection timing with pilot-main injection, as well as post injection ratio and post injection duration angle with pilot-main-post injection, were all investigated and optimized. The results indicate that retarding pilot injection timing with pilot-main injection declines high temperature region, resulting in a notable reduction in NOx emissions. Since fuel evaporation and burn are hampered by long spray penetration due to low temperature and pressure with pilot injection, a suitable spray included angle are used to offer more efficient air-fuel mixing process. A wider spray included angle simultaneously reduces soot emission and indicated specific fuel consumption (ISFC). Post injection fuel exerts impact on combustion process by causing a great disturbance to flow field during post combustion. Increasing post injection ratio from 4% to 10% at a small post injection duration angle great emission performance is achieved by simultaneous reduction in NOx and soot emissions while only using a slight consumption of ISFC. To summarize, the defeat of traditional NOx-soot trade-off occurs as both NOx and soot emissions are decreased with optimized multiple injection strategy and spray included angle. Particularly, there are respectively four cases with pilot-main injection and two cases with pilot-main-post injection, that achieve simultaneous reduction in NOx emissions, soot emission, and ISFC, compared to the prototype.

Experimental Investigation of Spray and Combustion Characteristics of Soybean Biodiesel in a Constant-Volume Combustion Chamber: The Effects of Fuel and Ambient Gas Temperature

2013 ◽  
Author(s):  
Yifeng Wu ◽  
Ronghua Huang ◽  
Chia-fon F. Lee
Keyword(s):  
Combustion Chamber ◽  
Ignition Delay ◽  
Combustion Characteristics ◽  
Constant Volume ◽  
Gas Temperature ◽  
Soot Mass ◽  
Soybean Biodiesel ◽  
Constant Volume Combustion ◽  
Constant Volume Combustion Chamber ◽  
Ambient Gas

Effects of fuel and ambient gas temperature on the spray and combustion characteristics of soybean biodiesel were studied in a constant-volume combustion chamber. Four different fuels or fuel blends including B0, B20, B50 and B100 were investigated experimentally. The soot mass data were obtained via a new technique called forward illumination light extinction (FILE). The ambient gas temperature was varied from 700 K to 1200 K. To simulate the engine operating conditions, the ambient oxygen concentration and its density were kept at 21 % and 15 kg/m3, respectively. A higher peak pressure is found as the biodiesel content decreases. B20, B50 and B100 have a shorter ignition delay than B0 and the ignition delay decreases with increasing biodiesel content. The liquid penetration decreases with decreasing biodiesel content. Moreover, the integrated natural flame luminosity (INFL) increases with decreasing biodiesel content. Shorter flame (i.e., soot luminosity) duration and a longer delay between start of combustion (SOC) and the appearance of flame are found as the biodiesel content increases. The flame duration also increases with increasing ambient gas temperature for all fuels. Soot is lower and appears later at a lower ambient gas temperature, while it is burned out at around the same time. Near-zero soot mass was observed for all tested fuels at 700 K. A shorter soot formation process is observed for biodiesel fuels. The soot reduction using B20 and B50 is not obvious compared to B0 at a low temperature. But under the ordinary diesel engine operating condition at 1000 K, the soot reduction is significant. It is also found that the soot can be reduced by 60% and above when B100 is used in this study.

Preinjection—A Measure to Influence Exhaust Quality and Noise in Diesel Engines

1989 ◽  
Vol 111 (3) ◽  
pp. 445-450 ◽  
Author(s):  
H. Schulte ◽  
E. Scheid ◽  
F. Pischinger ◽  
U. Reuter
Keyword(s):  
Diesel Engines ◽  
High Speed ◽  
Combustion Noise ◽  
Injection System ◽  
Pilot Injection ◽  
Load Range ◽  
Injection Nozzle ◽  
Black Smoke ◽  
Injection Quantity ◽  
Main Injection

The combustion noise generated by DI diesel engines can be clearly reduced during both steady-state and transient operation in applying a pilot injection. After optimization, a slight increase in fuel consumption is found in the upper load range. The pilot injection also tends to reduce the NOx emissions. An increase in black smoke emissions is considered to be the main drawback with pilot injection. High-speed Schlieren photographs of injection and combustion phenomena within a pressurized chamber show that the higher black smoke emissions may be due to the combustion of the main injection quantity that occurs in a mixture that is insufficiently prepared and with nearly no delay due to the pilot injection. On the basis of these findings, it is concluded that a high degree of atomization and rapid vaporization of the main injection quantity must be accomplished. To achieve these goals better, a separate injection nozzle for the pilot quantity is preferred to an injection system with a single injection nozzle, providing both the pilot and the main quantity. Therefore, rather simple injection systems with a separate pilot injector can be developed that provide a constant pilot quantity and controlled pilot injection time over the entire engine map.

Fuel efficiency analysis and peak pressure rise rate improvement for neat n-butanol injection strategies

2016 ◽  
Vol 231 (1) ◽  
pp. 50-65 ◽  
Author(s):  
Marko Jeftić ◽  
Zhenyi Yang ◽  
Graham T Reader ◽  
Ming Zheng
Keyword(s):  
Carbon Monoxide ◽  
Peak Pressure ◽  
Pressure Rise ◽  
Single Shot ◽  
Pilot Injection ◽  
Post Injection ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Main Injection ◽  
Injection Strategies

Engine tests were conducted to investigate the efficiency and the peak pressure rise rate performance of different fuel injection strategies for the direct injection of neat n-butanol in a compression ignition engine. Three different strategies were tested: a single-shot injection; a pilot injection; a post-injection. A single-shot injection timing sweep revealed that early injections had the highest indicated efficiency while late injections reduced the peak pressure rise rate at the cost of a slightly reduced thermal efficiency. Delayed single-shot injections also had increased emissions of nitrogen oxides, total hydrocarbon and carbon monoxide. Addition of a pilot injection had a negative effect on the peak pressure rise rate. Because of the low cetane number of butanol and the relatively lean and well-premixed air–fuel mixture, the pilot injection failed to autoignite and instead ignited simultaneously with the main injection. This resulted in slightly increased peak pressure rise rates and significantly increased unburned butanol hydrocarbon emissions. Conversely, the use of an early post-injection produced a noticeable engine power output and allowed the main injection to be shortened and the peak pressure rise rate to be substantially reduced. However, relatively early post-injections slightly reduced the indicated efficiency and increased the nitrogen oxide emissions and the carbon monoxide emissions compared with the single-shot injection strategy. These results recommended the use of a single-shot injection for low loads and medium loads owing to a superior thermal efficiency and suggested that the application of a post-injection may be more suited to high-load conditions because of the substantially reduced peak pressure rise rates.

Split Injection Strategies for Biodiesel-Fueled Premixed Charge Compression Ignition Combustion Engine—Part II: Particulate Studies

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Akhilendra Pratap Singh ◽  
Avinash Kumar Agarwal
Keyword(s):  
Fuel Injection ◽  
Combustion Engine ◽  
Chemical Characterization ◽  
Injection Pressure ◽  
Morphological Characterization ◽  
Pilot Injection ◽  
Compression Ignition ◽  
Main Injection ◽  
Fuel Injection Pressure ◽  
Injection Strategies

Abstract In this study, experiments were performed in a single-cylinder research engine to investigate the particulate matter (PM) characteristics of the engine operated in premixed charge compression ignition (PCCI) mode combustion vis-a-vis baseline compression ignition (CI) mode combustion using three test fuels, namely, B20 (20% v/v biodiesel blended with mineral diesel), B40 (40% v/v/ biodiesel blended with mineral diesel), and baseline mineral diesel. The experiments were carried out at constant fuel injection pressure (FIP) (700 bar), constant engine speed (1500 rpm), and constant fuel energy input (0.7 kg/h diesel equivalent). PM characteristics of PCCI mode combustion were evaluated using two different fuel injection strategies, namely, single pilot injection (SPI) (35 deg before top dead center (bTDC)) and double pilot injection (DPI) (35 deg and 45 deg bTDC) at four different start of main injection (SoMI) timings. Results showed that both PCCI mode combustion strategies emitted significantly lower PM compared to baseline CI mode combustion strategy. However, the blending of biodiesel resulted in relatively higher PM emissions from both CI and PCCI combustion modes. Chemical characterization of PM showed that PCCI mode combustion emitted relatively lower trace metals compared to baseline CI mode combustion, which reduced further for B20. For detailed investigations of particulate structure, morphological characterization was done using transmission electron microscopy (TEM), which showed that PM emitted by B20-fueled PCCI mode combustion posed potentially lower health risk compared to baseline mineral diesel-fueled CI mode combustion.

Experimental Investigation of Thermal Load in High Speed Direct Injection Diesel Engine Under the Control of Various Engine Performance Parameters

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
Jeonghoon Lee
Keyword(s):  
Diesel Engine ◽  
Thermal Load ◽  
High Speed ◽  
Direct Injection ◽  
Injection Timing ◽  
Pilot Injection ◽  
Performance Parameters ◽  
Full Load ◽  
Main Injection ◽  
Vibration Noise

Multiple injection strategies are being widely utilized to reduce the vibration, noise, and particle emission in diesel engines. A considerable amount of research related to attempts to increase the maximum power and to reduce vibration, noise, and particulate matters has been done. However, investigations of various performance parameters in terms of the thermal load in high speed direct injection engines are rarely to be found despite the fact that the relationship between these parameters and the reliability of the engine is important for mass production. Hence, the thermal load imposed on the cylinder head and cylinder block of a four-cylinder diesel engine was investigated under the most severe test conditions, at the rated speed and with a full load, by changing the performance parameters such as the main injection timing, the fuel pressure in the common rail, the boost pressure, the exhaust gas recirculation, the fuel quantity of the pilot injection, the timing of the pilot injection, the fuel quantity of the postinjection, and the timing of postinjection. Experimental results showed that the main injection timing among other parameters was the parameter that influenced the thermal load most at the rated engine speed and under a full load condition.

scholarly journals High-Speed 3D Printing of High-Performance Thermosetting Polymers via Two-Stage Curing

2018 ◽  
Vol 39 (7) ◽  
pp. 1700809 ◽  
Author(s):  
Xiao Kuang ◽  
Zeang Zhao ◽  
Kaijuan Chen ◽  
Daining Fang ◽  
Guozheng Kang ◽  
...  
Keyword(s):  
3D Printing ◽  
High Speed ◽  
High Performance ◽  
Two Stage ◽  
Thermosetting Polymers

scholarly journals Research on aerodynamic characteristics of two-stage axial micro air turbine spindle for small parts machining

2020 ◽  
Vol 12 (12) ◽  
pp. 168781402098437
Author(s):  
Liu Jiang ◽  
Guo Zhiping ◽  
Miao Shujing ◽  
He Xiangxin ◽  
Zhu Xinyu
Keyword(s):  
High Speed ◽  
Aerodynamic Characteristics ◽  
Maximum Efficiency ◽  
Two Stage ◽  
Output Torque ◽  
Air Turbine ◽  
Solid Foundation ◽  
Computational Fluid Dynamics Cfd ◽  
Micro Machine ◽  
Small Parts

In order to meet the requirements of output torque, efficiency and compact shape of micro-spindles for small parts machining, a two-stage axial micro air turbine spindle with an axial inlet and outlet is proposed. Based on the k-ω turbulence model of SST, the flow field and operation characteristics of the two-stage axial micro air turbine spindle were studied using computational fluid dynamics (CFD) combined with an experimental study. We obtained the air turbine spindle under different working conditions of the loss and torque characteristics. When the inlet pressure was 300 KPa, the output speed of the two-stage turbine was 100,000 rpm, 9% higher than that of a single-stage turbine output torque. The total torque reached 6.39 N·mm, and the maximum efficiency of the turbine and the spindle were 42.2% and 32.3%, respectively. Through the research on the innovative structure of the two-stage axial micro air turbine spindle, the overall performance of the principle prototype has been significantly improved and the problems of insufficient output torque and low working efficiency in high-speed micro-machining can be solved practically, which laid a solid foundation for improving the machining efficiency of small parts and reducing the size of micro machine tool.

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