Adaptive flow optimization of a turbocharger compressor to improve engine low speed performance

Yangjun Zhang,Chenfang Wang,Zheng Xinqian,Weilin Zhuge,Yulin Wu,Jianzhong Xu 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.6

To improve the engine overall performance, an adaptive flow optimization procedure is proposed in this paper to synthesize turbocharger compressor optimum designs. Two objective functions are involved in the adaptive optimization. They are the traditional compressor design and the compressor design with consideration of improving engine overall performance. The two-step decomposition approach is chosen to generate optimum designs. The optimized designs not only satisfy turbomachinery and engine constraints but also have optimum objective function values in the two fields. Performance sensitivity analysis of compressor main design variables is performed for the flow optimization design process. A centrifugal compressor is redesigned for a turbocharged gasoline engine, as an example, based on the adaptive flow optimization process. The calculating results show a more than 5% increase of isentropic efficiency in comparison with the base line compressor, resulting in a more than 19% increase of engine torque at low speed conditions.

Inheritance of Downy Mildew Resistance at Different Developmental Stages in Chinese Cabbage via the Leaf Disk Test

Shengju Zhang,Shuancang Yu,Fenglan Zhang,Longting Si,Yangjun Yu,Xiuyun Zhao,Deshuang Zhang,Weihong Wang 한국원예학회 2012 Horticulture, Environment, and Biotechnology Vol.53 No.5

Downy mildew, caused by Hyaloperonospora parasitica, is a destructive disease of the Chinese cabbage (Brassica rapa ssp. pekinensis). A rapid resistance/susceptibility test for H. parasitica was established by the inoculation of a leaf disk test. Four conditions were tested and the optimal condition was found when the inoculated leaf disk was placed into dark conditions at 16℃ for the first 24 hours after inoculation, followed by 5 days of light at 20℃and 23℃ for 4 hours and 5 hours, respectively, dark at 16℃ and 12℃ for 3 hours and 12 hours, respectively, and a final temperature of 16℃ for 24 hours. There was a good correlation between the resistance levels of leaf disks and the resistance of seedlings or adult plants, which indicated that testing leaf disks should be the preferred methods to predict the resistance of adult plants. Using this method, downy mildew resistance was investigated in a double haploid (DH) population at four developmental stages. The results showed that the genetic pattern, which was deduced from the DH segregation, was relatively similar, but varied slightly during plant development.

Study of Mechanism of Counter-rotating Turbine Increasing Two-Stage Turbine System Efficiency

Yanbin Liu,Yangjun Zhang,Weilin Zhuge,Xinqian Zheng,Shuyong Zhang,Junyue Zhang 한국유체기계학회 2013 International journal of fluid machinery and syste Vol.6 No.3

Two-stage turbocharging is an important way to raise engine power density, to realize energy saving and emission reducing. At present, turbine matching of two- stage turbocharger is based on MAP of turbine. The matching method does not take the effect of turbines' interaction into consideration, assuming that flow at high pressure turbine outlet and low pressure turbine inlet is uniform. Actually, there is swirl flow at outlet of high pressure turbine, and the swirl flow will influence performance of low pressure turbine which influencing performance of engine further. Three-dimension models of turbines with two-stage turbocharger were built in this paper. Based on the turbine models, mechanism of swirl flow at high pressure turbine outlet influencing low pressure turbine performance was studied and a two-stage radial counter-rotation turbine system was raised. Mechanisms of the influence of counter-rotation turbine system acting on low-pressure turbine were studied using simulation method. The research result proved that in condition of small turbine flow rate corresponding to engine low-speed working condition, counter-rotation turbine system can effectively decrease the influence of swirl flow at high pressure turbine outlet imposing on low pressure turbine and increases efficiency of the low-pressure turbine, furthermore increases the low-speed performance of the engine.

Study of Mechanism of Counter-rotating Turbine Increasing Two-Stage Turbine System Efficiency

Liu, Yanbin,Zhuge, Weilin,Zheng, Xinqian,Zhang, Yangjun,Zhang, Shuyong,Zhang, Junyue Korean Society for Fluid machinery 2013 International journal of fluid machinery and syste Vol.6 No.3

Two-stage turbocharging is an important way to raise engine power density, to realize energy saving and emission reducing. At present, turbine matching of two-stage turbocharger is based on MAP of turbine. The matching method does not take the effect of turbines' interaction into consideration, assuming that flow at high pressure turbine outlet and low pressure turbine inlet is uniform. Actually, there is swirl flow at outlet of high pressure turbine, and the swirl flow will influence performance of low pressure turbine which influencing performance of engine further. Three-dimension models of turbines with two-stage turbocharger were built in this paper. Based on the turbine models, mechanism of swirl flow at high pressure turbine outlet influencing low pressure turbine performance was studied and a two-stage radial counter-rotation turbine system was raised. Mechanisms of the influence of counter-rotation turbine system acting on low-pressure turbine were studied using simulation method. The research result proved that in condition of small turbine flow rate corresponding to engine low-speed working condition, counter-rotation turbine system can effectively decrease the influence of swirl flow at high pressure turbine outlet imposing on low pressure turbine and increases efficiency of the low-pressure turbine, furthermore increases the low-speed performance of the engine.

Dynamic optimization design of the suspension parameters of car bodymounted equipment via analytical target cascading

Jie Chen,Yangjun Wu,Limin Zhang,Xiaolong He,Shijie Dong 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5

Under dynamic conditions, the dynamic force between the suspended equipment and the car body is substantially increased. This increase not only affects the ride comfort but also substantially raises the likelihood of fatigue damage to the suspended equipment. A multiobjective analytical target cascading (ATC) optimization is proposed to improve the ride comfort of high-speed trains and reduce the vibration of the suspended equipment. A mathematical simulation model of the vehicle equipment system is established, and the acceleration frequency-response function expression of the car body and the suspension system is obtained. The comfort index of the car body and the acceleration root mean square (RMS) of the suspended equipment are calculated by combining the German vertical irregular track spectrum and the comfort filter function. Meanwhile, the ATC method is used to optimize the car body comfort index and the acceleration RMS of the underframe suspended equipment. Then, the availability of the optimization method is evaluated via numerical simulation. Compared with the original suspension scheme of the underframe equipment, when the running speed of the vehicle is 300 km/h, the RMS value of the vibrational acceleration of the underframe equipment after optimization decreases by 19.9 %, and the ride comfort indexes at the car body center and above the front and rear bogies are improved by 6.4 %, 0.1 %, and 1.1 %, respectively. Simulation results demonstrate that ATC optimization can improve the railway vehicle ride comfort and reduce the vibration of the suspended equipment. This paper provides a new approach to the suspension parameter design of equipment.

RESEARCH ON THE INTEGRATED INTERCOOLER INTAKE SYSTEM OF TURBOCHARGED DIESEL ENGINE

Sheng Liu,Yangjun Zhang 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.2

In order to improve the compactness and performance of the intake system of turbocharged diesel engines, an integrated intercooler intake system is provided. Porous media computational fluid dynamics (CFD) model is used to analyze the flow and heat exchange performance of the integrated intercooler. The flow resistance, pressure fluctuation, temperature and pressure distribution of integrated intercoolers with different structures are compared by CFD simulation. The simulation results show that the best performance is achieved by the structure with central air intake with a baffle. Experimental study has been carried out to investigate the steady and transient performance of diesel engine with the original or integrated intercooler intake system. The test results show that with the use of the integrated intercooler intake system, the brake specific fuel consumption can be reduced by 5.9 g/kW·h at the rated condition, and the response time is reduced by 20.4 % under medium speed loading process.

Comparison of the main compounds in Fuding white tea infusions from various tea types

Junxian Pan,Yulan Jiang,Yangjun Lv,Man Li,Shikang Zhang,Jun Liu,Yuejin Zhu,Haihua Zhang 한국식품과학회 2018 Food Science and Biotechnology Vol.27 No.5

The purpose of this study was to compare the main components, and particularly catechins, caffeine, theanine, free amino acids, and water extracts, in Bai Hao Yin Zhen, Bai Mu Dan, and Shou Mei Fuding white tea infusions brewed at different temperatures, and their contributions to taste were estimated by dose-over-threshold value. Infusion temperature had a distinct effect on the main components extracted, and 100 C was found to be optimal for extracting catechins and caffeine. However, the effect of temperature on theanine, free amino acids, and water extracts varied with tea type. Bai Mu Dan and Shou Mei yielded a higher content of the major compounds than did Bai Hao Yin Zhen. Thus, infusion temperature had a large effect on extracting the main compounds, and the differences in content between the three white teas presumably reflected differences in the harvest time, processing method or leaf shape.

Synthesis and Photovoltaic Properties of Alternating Conjugated Polymers Derived from Thiophene-Benzothiadiazole Block and Fluorene/Indenofluorene Units

Li, Jianfeng,Tong, Junfeng,Zhang, Peng,Yang, Chunyan,Chen, Dejia,Zhu, Yuancheng,Xia, Yangjun,Fan, Duowang Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.2

A new donor-accepter-donor-accepter-donor (D-A-D-A-D) type 2,1,3-benzothiadiazole-thiophene-based acceptor unit 2,5-di(4-(5-bromo-4-octylthiophen-2-yl)-2,1,3-benzothiadiazol-7-yl)thiophene ($DTBTTBr_2$) was synthesized. Copolymerized with fluorene and indeno[1,2-b]fluorene electron-rich moieties, two alternating narrow band gap (NBG) copolymers PF-DTBTT and PIF-DTBTT were prepared. And two copolymers exhibit broad and strong absorption in the range of 300-700 nm with optical band gap of about 1.75 eV. The highest occupied molecular orbital (HOMO) energy levels vary between -5.43 and -5.52 eV and the lowest unoccupied molecular orbital (LUMO) energy levels range from -3.64 to -3.77 eV. Potential applications of the copolymers as electron donor material and $PC_{71}BM$ ([6,6]-phenyl-$C_{71}$ butyric acid methyl ester) as electron acceptors were investigated for photovoltaic solar cells (PSCs). Photovoltaic performances based on the blend of PF-DTBTT/$PC_{71}BM$ (w:w; 1:2) and PIF-DTBTT/$PC_{71}BM$ (w:w; 1:2) with devices configuration as ITO/PEDOT: PSS/blend/Ca/Al, show an incident photon-to-current conversion efficiency (IPCE) of 2.34% and 2.56% with the open circuit voltage ($V_{oc}$) of 0.87 V and 0.90 V, short circuit current density ($J_{sc}$) of $6.02mA/cm^2$ and $6.12mA/cm^2$ under an AM1.5 simulator ($100mA/cm^2$). The photocurrent responses exhibit the onset wavelength extending up to 720 nm. These results indicate that the resulted narrow band gap copolymers are viable electron donor materials for polymer solar cells.

Numerical study of a two-stage turbine characteristic under pulsating flow conditions

Rongchao Zhao,Weilin Zhuge,Yangjun Zhang,Mingyang Yang,Ricardo Martinez-Botas 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.2

With developments of turbo-compounding and two-stage turbocharging technologies, two-stage turbine is increasingly applied in automotive engines. This paper numerically investigates the characteristic of a two-stage turbine on a turbo-compound engine under pulsating flow conditions. The behaviors of turbine stages with the swallowing capacity ratio (SR) equals to 2.0, under low, mid and high load conditions were studied. Results show that the Low pressure turbine (LPT) is more sensitive to the pulsating flow, especially at low load conditions, compared with High pressure turbine (HPT). It is caused by the dramatic change of velocity ratio in LPT. Results also show that the load split between HPT and LPT under pulsating flow conditions deviates from that at quasi-steady conditions, indicating the different behaviors of the two-stage turbine under pulsating conditions.

Study on Through-flow Model for Turbine System Considering Three-dimensional Flow Field Distortion Effect

Yanbin Liu,Weilin Zhuge,Yangjun Zhang,Shuyong Zhang 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.4

Turbocharging is an important way to raise engine power density, save energy and reduce emission. Because turbocharger is driven by exhaust gas, energy utilization rate is a key factor for turbocharged engine performance. As a part transferring heat to mechanical energy, turbine efficiency decides exhaust gas energy utilization. Because of three-dimensional flow field distortion effect at outlet to exhaust manifold, turbine efficiency will be different from MAP when engine working. Influences by interaction in turbine system, turbine efficiency will decrease. So in order to evaluate turbine operating performance and design or select turbine more precisely, it is necessary to build a through-flow model for turbine which can consider three-dimensional flow field distortion effect. Unsteady flow field distortion at outlet to turbine was analyzed and flow field interaction law between exhaust manifold and turbine was studied. On the basis, six typical flow field distortion models in an engine operation cycle were raised. Then influences six models on each flow stage in turbine were analyzed. Further, models for exhaust manifold and turbine were built separately. Difference between unsteady three-dimensional simulation result and that based on turbine system through-flow model was compared and analyzed. Research result illustrated that difference of turbine cycle efficiency was only 0.1% and difference of turbine cycle work was 0.3%. So it can be deduced that turbine system through-flow model can predict turbine operation performance precisely and help turbine system matching exactly.