Study on Flow Instability and Countermeasure in a Draft tube with Swirling flow

Takahiro Nakashima,Ryo Matsuzaka,Kazuyoshi Miyagawa,Koichi Yonezawa,Yoshinobu Tsujimoto 한국유체기계학회 2015 International journal of fluid machinery and syste Vol.8 No.4

The swirling flow in the draft tube of a Francis turbine can cause the flow instability and the cavitation surge and has a larger influence on hydraulic power operating system. In this paper, the cavitating flow with swirling flow in the diffuser was studied by the draft tube component experiment, the model Francis turbine experiment and the numerical simulation. In the component experiment, several types of fluctuations were observed, including the cavitation surge and the vortex rope behaviour by the swirling flow. While the cavitation surge and the vortex rope behaviour were suppressed by the aeration into the diffuser, the loss coefficient in the diffuser increased by the aeration. In the model turbine test the aeration decreased the efficiency of the model turbine by several percent. In the numerical simulation, the cavitating flow was studied using Scale-Adaptive Simulation (SAS) with particular emphasis on understanding the unsteady characteristics of the vortex rope structure. The generation and evolution of the vortex rope structures have been investigated throughout the diffuser using the iso-surface of vapor volume fraction. The pressure fluctuation in the diffuser by numerical simulation confirmed the cavitation surge observed in the experiment. Finally, this pressure fluctuation of the cavitation surge was examined and interpreted by CFD.

Study on Flow Instability and Countermeasure in a Draft tube with Swirling flow

Nakashima, Takahiro,Matsuzaka, Ryo,Miyagawa, Kazuyoshi,Yonezawa, Koichi,Tsujimoto, Yoshinobu Korean Society for Fluid machinery 2015 International journal of fluid machinery and syste Vol.8 No.4

The swirling flow in the draft tube of a Francis turbine can cause the flow instability and the cavitation surge and has a larger influence on hydraulic power operating system. In this paper, the cavitating flow with swirling flow in the diffuser was studied by the draft tube component experiment, the model Francis turbine experiment and the numerical simulation. In the component experiment, several types of fluctuations were observed, including the cavitation surge and the vortex rope behaviour by the swirling flow. While the cavitation surge and the vortex rope behaviour were suppressed by the aeration into the diffuser, the loss coefficient in the diffuser increased by the aeration. In the model turbine test the aeration decreased the efficiency of the model turbine by several percent. In the numerical simulation, the cavitating flow was studied using Scale-Adaptive Simulation (SAS) with particular emphasis on understanding the unsteady characteristics of the vortex rope structure. The generation and evolution of the vortex rope structures have been investigated throughout the diffuser using the iso-surface of vapor volume fraction. The pressure fluctuation in the diffuser by numerical simulation confirmed the cavitation surge observed in the experiment. Finally, this pressure fluctuation of the cavitation surge was examined and interpreted by CFD.

Gender Differences in Pre- and Postoperative Health-Related Quality of Life Measures in Patients Who Have Had Decompression Surgery for Lumbar Spinal Stenosis

Yoshiomi Kobayashi,Yoji Ogura,Takahiro Kitagawa,Yoshiro Yonezawa,Yohei Takahashi,Akimasa Yasuda,Yoshio Shinozaki,Jun Ogawa 대한척추외과학회 2020 Asian Spine Journal Vol.14 No.2

Study Design: Retrospective chart audit. Purpose: This study aimed to investigate the gender difference in pre- and postoperative health-related quality of life (HRQOL) in patients who have had decompression surgery for lumbar spinal stenosis (LSS). Overview of Literature: Gender differences may contribute to variations in disease presentations and health outcomes. The influence of gender on pre- and postoperative HRQOL in spinal disorders remains unclear. Methods: We reviewed 125 patients (79 men and 46 women) who had lumbar spinous process splitting laminectomy (LSPSL) for LSS. We assessed the following clinical information: Japanese Orthopedic Association (JOA) score; numerical rating scale (NRS) for low back pain (LBP), leg pain, and leg numbness; Zurich Claudication Questionnaire; JOA Back Pain Evaluation Questionnaire; Roland-Morris Disability Questionnaire (RMDQ); and Short Form 8 (SF-8) as HRQOL. We compared the HRQOLs of men and women pre- and postoperatively. Results: Although the preoperative NRS results for LBP were significantly higher in women (p<0.05), there were no significant differences in clinical outcomes between men and women postoperatively. For HRQOL, the RMDQ scores were significantly worse in women preoperatively (p<0.05), but no significant differences were found postoperatively between men and women. Similarly, the SF-8 mental health score was also significantly lower in women preoperatively (p<0.05), but no significant differences were noted between the two groups postoperatively. Conclusions: LSPSL greatly reduced LBP, leg pain, and leg numbness in both genders. There were limited differences in pain and several HRQOL questionnaire responses between men and women after surgery. We found that women had greater sensitivity to and/or lower tolerance for pain than men, which led to lower HRQOL mental health scores preoperatively.

Complete mitochondrial genome sequence of Tosa-Jidori sheds light on the origin and evolution of Japanese native chickens

Osman Sayed A.-M.,Nishibori Masahide,Yonezawa Takahiro 아세아·태평양축산학회 2021 Animal Bioscience Vol.34 No.6

Objective: In Japan, approximately 50 breeds of indigenous domestic chicken, called Japanese native chickens (JNCs), have been developed. JNCs gradually became established based on three major original groups, “Jidori”, “Shoukoku”, and “Shamo”. Tosa-Jidori is a breed of Jidori, and archival records as well as its morphologically primitive characters suggest an ancient origin. Although Jidori is thought to have been introduced from East Asia, a previous study based on mitochondrial D-loop sequences demonstrated that Tosa- Jidori belongs to haplogroup D, which is abundant in Southeast Asia but rare in other regions, and a Southeast Asian origin for Tosa-Jidori was therefore suggested. The relatively small size of the D-loop region offers limited resolution in comparison with mitogenome phylogeny. This study was conducted to determine the phylogenetic position of the Tosa-Jidori breed based on complete mitochondrial D-loop and mitogenome sequences, and to clarify its evolutionary relationships, possible maternal origin and routes of introduction into Japan. Methods: Maximum likelihood and parsimony trees were based on 133 chickens and consisted of 86 mitogenome sequences as well as 47 D-loop sequences. Results: This is the first report of the complete mitogenome not only for the Tosa-Jidori breed, but also for a member of one of the three major original groups of JNCs. Our phylogenetic analysis based on D-loop and mitogenome sequences suggests that Tosa- Jidori individuals characterized in this study belong to the haplogroup D as well as the sub-haplogroup E1. Conclusion: The sub-haplogroup E1 is relatively common in East Asia, and so although the Southeast Asian origin hypothesis cannot be rejected, East Asia is another possible origin of Tosa-Jidori. This study highlights the complicated origin and breeding history of Tosa-Jidori and other JNC breeds. Objective: In Japan, approximately 50 breeds of indigenous domestic chicken, called Japanese native chickens (JNCs), have been developed. JNCs gradually became established based on three major original groups, “Jidori”, “Shoukoku”, and “Shamo”. Tosa-Jidori is a breed of Jidori, and archival records as well as its morphologically primitive characters suggest an ancient origin. Although Jidori is thought to have been introduced from East Asia, a previous study based on mitochondrial D-loop sequences demonstrated that Tosa-Jidori belongs to haplogroup D, which is abundant in Southeast Asia but rare in other regions, and a Southeast Asian origin for Tosa-Jidori was therefore suggested. The relatively small size of the D-loop region offers limited resolution in comparison with mitogenome phylogeny. This study was conducted to determine the phylogenetic position of the Tosa-Jidori breed based on complete mitochondrial D-loop and mitogenome sequences, and to clarify its evolutionary relationships, possible maternal origin and routes of introduction into Japan.Methods: Maximum likelihood and parsimony trees were based on 133 chickens and consisted of 86 mitogenome sequences as well as 47 D-loop sequences. Results: This is the first report of the complete mitogenome not only for the Tosa-Jidori breed, but also for a member of one of the three major original groups of JNCs. Our phylogenetic analysis based on D-loop and mitogenome sequences suggests that TosaJidori individuals characterized in this study belong to the haplogroup D as well as the sub-haplogroup E1.Conclusion: The sub-haplogroup E1 is relatively common in East Asia, and so although the Southeast Asian origin hypothesis cannot be rejected, East Asia is another possible origin of Tosa-Jidori. This study highlights the complicated origin and breeding history of Tosa-Jidori and other JNC breeds.