Article
Energy & Fuels
Dongfang Wang, Zhongjie Shi, Ziming Yang, Haiyan Chen, Manlin Wang, Yikai Li
Summary: The heat transfer between the wall and spray has a significant impact on the ignition characteristics of diesel engines. The interaction between the spray and wall leads to smaller droplet size and more small and large droplets compared to free spray. This interaction increases the total surface area of the droplets and promotes heat transfer, which is beneficial for the ignition process. However, when the wall temperature is low, the spray is cooled by the wall, inhibiting ignition.
Article
Energy & Fuels
Dongfang Wang, Zhongjie Shi, Ziming Yang, Haiyan Chen, Manlin Wang, Yikai Li
Summary: The study found that spray penetration length, cone angle, spread radius, and vapor-phase floatation height were not sensitive to ambient temperature, but liquid-phase floatation height decreased with increasing ambient temperature. Ignition delay time decreased with increasing ambient temperature, and ignition positions were near the wall surface and away from the nozzle axis. Additionally, the distance between ignition position and nozzle axis, as well as the distance between ignition position and wall, decreased with increasing ambient temperature.
Article
Chemistry, Multidisciplinary
Chuanxin Bai, Kai Liu, Tong Zhao, Jinjin Liu
Summary: This study developed a numerical model to investigate the heat transfer characteristics and wall film formation of spray impinging on the wall in the SCR system. The model used the Eulerian-Lagrangian approach, with the Lagrangian approach representing the spray generated by a pressure-driven injector and the Eulerian approach representing exhaust gas. The Stochastic Kuhnke Model was applied to spray/wall interaction and accurately estimated the heat transfer characteristics. The study also analyzed the causes of spray local cooling and rapid cooling effects, and derived the correlation between critical transition temperature and critical heat flux temperature for wall film formation.
APPLIED SCIENCES-BASEL
(2023)
Article
Energy & Fuels
Dongfang Wang, Jiahao Zhang, Yikai Li, Ziming Yang, Zhongjie Shi, Yue Lou
Summary: The dynamics of low temperature combustion and intermediate temperature combustion significantly affect high temperature combustion and engine performance. Optical experiments were conducted to reveal the transition from low temperature combustion to intermediate temperature combustion and high temperature combustion in spray combustion under low ambient temperatures. The results show that the pressure in the combustion chamber increases significantly at low ambient temperatures and the transition can be diagnosed based on luminosity variations.
Article
Thermodynamics
Can Yang, Xiaobei Cheng, Qingqi Li, Yingda Wang
Summary: This study investigates the impact of wall temperature and impingement distance on diesel spray ignition and combustion. Experimental results show that increasing wall temperature enhances auto-ignition and combustion process, but the effect weakens with larger impingement distances. When wall temperature is high, decreasing impingement distance promotes fuel evaporation and mixing, whereas at low wall temperatures, cooling effect dominates. Additionally, the ignition points are closer to the wall with higher wall temperatures, especially at shorter impingement distances, suggesting enhanced combustion and heat transfer near the wall.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Abdallah Ahmed, Edward Wright, Fawzy Abdel-Aziz, Yuying Yan
Summary: The study introduced a novel reverse jet impingement technique into a double-wall cooling structure to enhance heat transfer. Various factors, such as nozzle configuration and jet-to-target spacing, were found to affect the heat transfer effectiveness within gas turbine engines.
APPLIED THERMAL ENGINEERING
(2021)
Article
Thermodynamics
Dehai Kong, Tao Guo, Zhao Ma, Cunliang Liu, Sergey Isaev
Summary: This study investigated the effect of a corrugated wall jet on impingement heat transfer and flow loss in a narrow target chamber. Results show that corrugated jet plates yield better heat transfer performance at a relatively high Reynolds number and low impinging distance. The discharge coefficient for the corrugated jet plate was lower than that of the flat jet plate, with the minimum reached at a certain corrugation amplitude.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Li Yi, Haozhong Hu, Chao li, Ying Zhang, Shu Yang, Minqiang Pan
Summary: The study compared the flow character and thermal performance of two novel micro-jet impingement vapor chamber configurations with a traditional liquid cooling vapor chamber. The results show that the integrated heat sink design outperforms the traditional vapor chamber in terms of heat transfer performance. This research has promising implications for efficient heat transfer technology in high heat flux applications.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Energy & Fuels
Dongfang Wang, Zhongjie Shi, Yikai Li, Ziming Yang, Haiyan Chen, Chenghan Sun
Summary: To investigate the effect of the wall on soot formation during spray combustion and explain the contradictory results, the vapor-phase, ignition, combustion, and soot formation of free-and impingement-spray were studied at different wall temperatures. Optical diagnostic techniques were used for comparison. The results show that compared to free spray, impingement spray has reduced vapor-phase spray tip penetration and increased vapor-phase spray volume. It also has a shorter ignition delay time when only the vapor-phase impinges on the wall. The soot formation of impingement spray is approximately one-third of free spray due to increased air entrainment. The relationship between wall temperature and soot formation is non-linear.
Article
Thermodynamics
A. Gholijani, T. Gambaryan-Roisman, P. Stephan
Summary: This experimental study investigates the hydrodynamics and heat transport during the horizontal coalescence of two drops impinging a hot wall. The results show that heat flow is reduced during various stages of drop coalescence, and that an increase in wall superheat leads to a reduction in drop footprint and an increase in heat flow.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2022)
Article
Energy & Fuels
Yaozong Li, Xiangrong Li, Weiren Cao, Zhicheng Shi, Yaqing Bo, Han Wu
Summary: Impinging spray ignition has been studied through 3-D simulation at different ambient temperatures and wall temperatures, revealing that fuel-air mixing and ignition processes are influenced by wall cooling. As temperature decreases, attached fuel mass increases linearly and ignition threshold rises, while the participation of fuel film in combustion decreases.
Article
Thermodynamics
Herry Sufyan Hadi, Chengyuan Fan, Atsushi Takayama, Keiya Nishida, Yoichi Ogata
Summary: The relationship between diesel spray impingement, combustion processes, and heat loss was investigated using a rapid compression and expansion machine (RCEM). The study found that the impingement flame surrounding the cylinder head contributed to the highest magnitude and longest duration of the heat flux on the cylinder side.
APPLIED THERMAL ENGINEERING
(2023)
Article
Energy & Fuels
Han Wu, Xinyi Dong, Zhicheng Shi, Haiying Li, Sheng Miao, Weiren Cao, Yaqing Bo, Lu Zhang, Xiangrong Li
Summary: The effect of injection pressure on diesel ignition is complex, with low-pressure injection being preferred for liquid impingement, while moderately elevated injection pressures under vapor impingement and free spray facilitate fast ignition and optimized heat release.
Article
Thermodynamics
Chuansheng Liu, Chenglong Tang, Haibao Mu, Zuohua Huang
Summary: A data fusion method combining POD and CS is proposed for high spatiotemporal resolution temperature measurement of rocket engine combustor chamber walls.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Karri Keskinen, Walter Vera-Tudela, Yuri M. Wright, Konstantinos Boulouchos
Summary: This study investigates the wall heat transfer process in diesel engines and the effect of coatings on heat transfer performance. Experiments involve controlled conditions with different injection parameters and coatings made of thermal swing materials. Results indicate that the surface roughness of coatings has a significant impact on wall heat flux.
INTERNATIONAL JOURNAL OF ENGINE RESEARCH
(2021)
