Combustion noise takes large proportion in diesel engine noise and the studies of its influence factors play an important role in noise reduction. Engine noise and cylinder pressure measurement experiments were carrie...Combustion noise takes large proportion in diesel engine noise and the studies of its influence factors play an important role in noise reduction. Engine noise and cylinder pressure measurement experiments were carried out. And the improved attenuation curves were obtained, by which the engine noise was predicted. The effect of fuel injection parameters in combustion noise was investigated during the combustion process. At last, the method combining single variable optimization and multivariate combination was introduced to online optimize the combustion noise. The results show that injection parameters can affect the cylinder pressure rise rate and heat release rate, and consequently affect the cylinder pressure load and pressure oscillation to influence the combustion noise. Among these parameters, main injection advance angle has the greatest influence on the combustion noise, while the pilot injection interval time takes the second place, and the pilot injection quantity is of minimal impact. After the optimal design of the combustion noise, the average sound pressure level of the engine is distinctly reduced by 1.0 d B(A) generally. Meanwhile, the power, emission and economy performances are ensured.展开更多
This study was carried out to predict the impact of injection timing and injection duration on engine brake power and Nitrogen Oxides emissions in a diesel engine using biofuel Soya Methyl Ester (SME). Predictions wer...This study was carried out to predict the impact of injection timing and injection duration on engine brake power and Nitrogen Oxides emissions in a diesel engine using biofuel Soya Methyl Ester (SME). Predictions were accomplished at three different injection timings 10<span style="white-space:nowrap;">°</span>, 5<span style="white-space:nowrap;">°</span> Crank Angle (CA) before Top Dead Center (bTDC) and 0<span style="white-space:nowrap;">° </span>CA at Top Dead Center (TDC) and four injection durations 20<span style="white-space:nowrap;">°</span>, 25<span style="white-space:nowrap;">°</span>, 30<span style="white-space:nowrap;">°</span>, 35<span style="white-space:nowrap;">°</span> CA. The study was conducted using a simulation software (Diesel-RK). The predicted results showed that the power<span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> produced by all the setups of the different injection timings </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">are</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> almost equal, but they differ in injection durations, e.g. the power at setup (10<span style="white-space:nowrap;">°</span> CA</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">bTDC) duration 20<span style="white-space:nowrap;">°</span> CA and 2500 rpm equal to 52 kW, at setup (5<span style="white-space:nowrap;">°</span> CA</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">bTDC) duration 25<span style="white-space:nowrap;">° </span>CA and same engine speed the power is equal to 51 kW, and at setup (0<span style="white-space:nowrap;">°</span> CA</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">TDC) durations 30<span style="white-space:nowrap;">°</span> the power is equal to 51 kW. The power in all setups are decreased as the injection duration increased, e.g. at setup 0<span style="white-space:nowrap;">°</span> CA TDC durations 25<span style="white-space:nowrap;">°</span>, 35<span style="white-space:nowrap;">°</span>, and 40<span style="white-space:nowrap;">°</span> CA and at 4000 rpm, the brake powers are equal 71, 65, and 59 kW respectively, thus the reduction percentages are 9% and 17% when compared to the 25<span style="white-space:nowrap;">°</span> injection duration. The nitrogen oxides emissions decreased as the injection duration is increased, e.g. the emissions at setup (10<span style="white-space:nowrap;">°</span> CA</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">bTDC) durations 25<span style="white-space:nowrap;">°</span>, 30<span style="white-space:nowrap;">°</span>, and 40<span style="white-space:nowrap;">°</span> CA and at 2500 rpm are equal 852, 589, 293 ppm respectively, the reduction percentages are 30% and 72%. The variations of injection timing and injection duration </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">have </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">taken a weighty influence on engine performance and emissions. The results </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">are</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> considered as a novelty in the field of using pure biofuel Soya Methyl Ester in diesel engine according to our information.</span></span></span>展开更多
With increasingly stringent emission regulations and demand for fuel economy by the public,the combustion and emission problems of automotive diesel engines during transient operation have become vital and urgent issu...With increasingly stringent emission regulations and demand for fuel economy by the public,the combustion and emission problems of automotive diesel engines during transient operation have become vital and urgent issues.In this study,combustion deterioration has been experimentally analyzed using a heavy-duty turbocharged diesel engine running under transient conditions(constant speed and increasing torque).Optimization of the transient combustion process was performed by adjusting the fuel injection parameters.The results indicated that the notable combustion deterioration relative to steady state operation while transient was a function of the delay in the air-supply to the turbocharged engine,and took the form of combustion phasing delay,resulting in rapidly increasing smoke emission and fuel consumption.However,the delay in combustion phasing can be controlled by advancing the fuel injection timing,effectively increasing thermal efficiency.Unfortunately,smoke and NO x emissions increased at the same time.The deterioration in combustion phasing can also be improved by increasing injection pressure,resulting in decreased smoke emission while NO x emission increased.It is worth noting that the effective thermal efficiency first increased and then decreased as fuel injection pressure increased during transient operation.展开更多
为探索轻型车用柴油机在中小负荷率工况下实现超低排放的预混合低温燃烧策略,以某四缸轻型车用柴油机为样机,在中小负荷率工况下,进行了喷射正时、废气再循环率(exhaust gas recirculation,EGR)、进气温度、喷射压力、预喷射等不同控制...为探索轻型车用柴油机在中小负荷率工况下实现超低排放的预混合低温燃烧策略,以某四缸轻型车用柴油机为样机,在中小负荷率工况下,进行了喷射正时、废气再循环率(exhaust gas recirculation,EGR)、进气温度、喷射压力、预喷射等不同控制参数对柴油机预混合低温燃烧影响的试验研究。证明适时早喷射可延长预混合期实现预混合燃烧,改善柴油机碳烟排放;采用高比例EGR技术降低进气氧浓度能有效控制预混合燃烧温度,可有效降低NOx排放,同时可推迟由早喷射造成的过早的燃烧相位;在适时早喷射结合高比例EGR的基础上,协同优化喷射压力、进气温度与预喷射参数改善NOx和碳烟排放Trade-off关系,以实现超低排放的预混合低温燃烧;通过预混合低温燃烧路径优化后,10%、25%和50%负荷率工况NOx排放与原机相比分别降低97.8%、80.7%和62.1%,碳烟排放分别降低76%、93.9%和47.1%。3个负荷率工况下优化后的有效燃油消耗率比优化前略有上升。研究结果为轻型柴油机预混合低温燃烧过程的优化及污染物排放控制技术提供了理论基础。展开更多
基金Project(2011BAE22B05)supported by the National Science and Technology Pillar Program during the 12th Five-year Plan of China
文摘Combustion noise takes large proportion in diesel engine noise and the studies of its influence factors play an important role in noise reduction. Engine noise and cylinder pressure measurement experiments were carried out. And the improved attenuation curves were obtained, by which the engine noise was predicted. The effect of fuel injection parameters in combustion noise was investigated during the combustion process. At last, the method combining single variable optimization and multivariate combination was introduced to online optimize the combustion noise. The results show that injection parameters can affect the cylinder pressure rise rate and heat release rate, and consequently affect the cylinder pressure load and pressure oscillation to influence the combustion noise. Among these parameters, main injection advance angle has the greatest influence on the combustion noise, while the pilot injection interval time takes the second place, and the pilot injection quantity is of minimal impact. After the optimal design of the combustion noise, the average sound pressure level of the engine is distinctly reduced by 1.0 d B(A) generally. Meanwhile, the power, emission and economy performances are ensured.
文摘This study was carried out to predict the impact of injection timing and injection duration on engine brake power and Nitrogen Oxides emissions in a diesel engine using biofuel Soya Methyl Ester (SME). Predictions were accomplished at three different injection timings 10<span style="white-space:nowrap;">°</span>, 5<span style="white-space:nowrap;">°</span> Crank Angle (CA) before Top Dead Center (bTDC) and 0<span style="white-space:nowrap;">° </span>CA at Top Dead Center (TDC) and four injection durations 20<span style="white-space:nowrap;">°</span>, 25<span style="white-space:nowrap;">°</span>, 30<span style="white-space:nowrap;">°</span>, 35<span style="white-space:nowrap;">°</span> CA. The study was conducted using a simulation software (Diesel-RK). The predicted results showed that the power<span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> produced by all the setups of the different injection timings </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">are</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> almost equal, but they differ in injection durations, e.g. the power at setup (10<span style="white-space:nowrap;">°</span> CA</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">bTDC) duration 20<span style="white-space:nowrap;">°</span> CA and 2500 rpm equal to 52 kW, at setup (5<span style="white-space:nowrap;">°</span> CA</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">bTDC) duration 25<span style="white-space:nowrap;">° </span>CA and same engine speed the power is equal to 51 kW, and at setup (0<span style="white-space:nowrap;">°</span> CA</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">TDC) durations 30<span style="white-space:nowrap;">°</span> the power is equal to 51 kW. The power in all setups are decreased as the injection duration increased, e.g. at setup 0<span style="white-space:nowrap;">°</span> CA TDC durations 25<span style="white-space:nowrap;">°</span>, 35<span style="white-space:nowrap;">°</span>, and 40<span style="white-space:nowrap;">°</span> CA and at 4000 rpm, the brake powers are equal 71, 65, and 59 kW respectively, thus the reduction percentages are 9% and 17% when compared to the 25<span style="white-space:nowrap;">°</span> injection duration. The nitrogen oxides emissions decreased as the injection duration is increased, e.g. the emissions at setup (10<span style="white-space:nowrap;">°</span> CA</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">bTDC) durations 25<span style="white-space:nowrap;">°</span>, 30<span style="white-space:nowrap;">°</span>, and 40<span style="white-space:nowrap;">°</span> CA and at 2500 rpm are equal 852, 589, 293 ppm respectively, the reduction percentages are 30% and 72%. The variations of injection timing and injection duration </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">have </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">taken a weighty influence on engine performance and emissions. The results </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">are</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> considered as a novelty in the field of using pure biofuel Soya Methyl Ester in diesel engine according to our information.</span></span></span>
基金supported by the National Natural Science Foundation of China(Grant No.51206060)the National Basic Research Program of China("973"Program)(Grant No.2013CB228402)
文摘With increasingly stringent emission regulations and demand for fuel economy by the public,the combustion and emission problems of automotive diesel engines during transient operation have become vital and urgent issues.In this study,combustion deterioration has been experimentally analyzed using a heavy-duty turbocharged diesel engine running under transient conditions(constant speed and increasing torque).Optimization of the transient combustion process was performed by adjusting the fuel injection parameters.The results indicated that the notable combustion deterioration relative to steady state operation while transient was a function of the delay in the air-supply to the turbocharged engine,and took the form of combustion phasing delay,resulting in rapidly increasing smoke emission and fuel consumption.However,the delay in combustion phasing can be controlled by advancing the fuel injection timing,effectively increasing thermal efficiency.Unfortunately,smoke and NO x emissions increased at the same time.The deterioration in combustion phasing can also be improved by increasing injection pressure,resulting in decreased smoke emission while NO x emission increased.It is worth noting that the effective thermal efficiency first increased and then decreased as fuel injection pressure increased during transient operation.
文摘为探索轻型车用柴油机在中小负荷率工况下实现超低排放的预混合低温燃烧策略,以某四缸轻型车用柴油机为样机,在中小负荷率工况下,进行了喷射正时、废气再循环率(exhaust gas recirculation,EGR)、进气温度、喷射压力、预喷射等不同控制参数对柴油机预混合低温燃烧影响的试验研究。证明适时早喷射可延长预混合期实现预混合燃烧,改善柴油机碳烟排放;采用高比例EGR技术降低进气氧浓度能有效控制预混合燃烧温度,可有效降低NOx排放,同时可推迟由早喷射造成的过早的燃烧相位;在适时早喷射结合高比例EGR的基础上,协同优化喷射压力、进气温度与预喷射参数改善NOx和碳烟排放Trade-off关系,以实现超低排放的预混合低温燃烧;通过预混合低温燃烧路径优化后,10%、25%和50%负荷率工况NOx排放与原机相比分别降低97.8%、80.7%和62.1%,碳烟排放分别降低76%、93.9%和47.1%。3个负荷率工况下优化后的有效燃油消耗率比优化前略有上升。研究结果为轻型柴油机预混合低温燃烧过程的优化及污染物排放控制技术提供了理论基础。