BACKGROUND Despite advancements,endoscopic retrograde cholangiopancreatography(ERCP)poses challenges,including the risk of post-ERCP pancreatitis and difficulty of biliary cannulation.AIM To compare dome and tapered t...BACKGROUND Despite advancements,endoscopic retrograde cholangiopancreatography(ERCP)poses challenges,including the risk of post-ERCP pancreatitis and difficulty of biliary cannulation.AIM To compare dome and tapered tip sphincterotomes,focusing on their efficacy in achieving successful biliary cannulation and reducing the incidence of post-ERCP pancreatitis.METHODS In this prospective,single-blind,randomized pilot study conducted at Inha Uni-versity Hospital,85 patients undergoing ERCP were equally divided into dome and tapered tip sphincterotome groups.The co-primary outcomes were the success rate of selective biliary cannulation and incidence of post-ERCP pancre-atitis.The secondary outcomes included biliary cannulation time,number of unintended pancreatic duct access events,and total procedure time.RESULTS The success rates of selective biliary cannulation were 74.4%and 85.7%in the dome and tapered tip groups,respectively,with no significant difference(P=0.20).Similarly,the incidence of post-ERCP pancreatitis did not differ significantly between the groups(5 cases in the tapered tip group vs 6 in the dome tip group,P=0.72).However,difficult cannulation was significantly more common in the dome tip group than in the tapered tip group(P=0.05).Selective biliary cannula-tion time emerged as a significant predictor of post-ERCP pancreatitis(multivariate odds ratio=9.33,95%confi-dence interval:1.31-66.44,P=0.03).CONCLUSION This study indicated that the sphincterotome tip type does not markedly affect biliary cannulation success or post-ERCP pancreatitis rates.However,cannulation duration is a key risk factor for post-ERCP pancreatitis.These findings provide preliminary insights that highlight the importance of refining ERCP practices,including sphinc-terotome selection,while underscoring the need for larger multicenter studies to improve procedure time and patient safety.展开更多
Base on the standard k-ωturbulent model,numerical method for solving three dimensional Reynolds Averaged Navier-Stokes(RANS)was adopted to study the aerothermal characteristics of the turbine blade with casing relati...Base on the standard k-ωturbulent model,numerical method for solving three dimensional Reynolds Averaged Navier-Stokes(RANS)was adopted to study the aerothermal characteristics of the turbine blade with casing relative motion.Experimental data were used to verify the effectiveness of the numerical method and turbulent model.The effect of blade tip clearance,geometry and relative motion on blade tip aerothermal characteristics were analyzed.The numerical results show that for the flat tip,relative motion can effectively suppress tip leakage and reduce leakage vortex size at rotating blade-static casing(BRCS)and static bladerotating casing(BSCR)conditions.A high level of heat transfer region can be observed near the leading edge at the conditions of rotating bladerotating casing(BRCS)and static bladestatic casing(BSCR).The blade tip heat transfer coefficient expands with the increase of tip clearance at different relative motion modes.At the brcs and bscs,the axial average heat transfer trend is the closest when the tip clearance is 1.5%H.The scraping vortex generated by relative motion at brcr and bscs inhib-its the development of leakage flow for squealer tip because of its sealing effect.High level of heat transfer region is also concentrated in the leading edge at brcr and bscs.The size of scraping vortex weakens with the increase of cavity depth.The distribution trend of the average heat transfer coefficient is similar in the two cases of relative static and relative motion,except for the case of 2.5%H cavity depth.展开更多
For unshrouded blade tip,the high-temperature gas flows through the tip clearance by force of the lateral pressure difference.Thereby,the blade tip endures increasing thermal load.Furthermore,the conventional blade ti...For unshrouded blade tip,the high-temperature gas flows through the tip clearance by force of the lateral pressure difference.Thereby,the blade tip endures increasing thermal load.Furthermore,the conventional blade tip treatment cannot continuously provide protection for the deteriorating service environment.In the present study,aerothermal characteristics of the squealer blade tip with staggered ribs,partial squealer rim and different partial squealer rim thickness were investigated to explore the influences of ribbed-cavity tip on the tip heat transfer,leakage flow and turbine stage efficiency.The numerical results indicate that the ribbed-cavity tips are beneficial for the reduction of the blade tip thermal load and leakage flow.Among the present six blade tip designs,the minimal area-averaged heat transfer coefficient is obtained by the case with the staggered ribs and a deeper squealer rim,which is reduced by 31.41%relative to the squealer tip.Plus,the blade tip modification closer to leading edge or tip mid-chord region performs better than trailing edge in reducing the tip leakage flow.展开更多
基金Supported by the Shihwa Medical Center Research Fund.
文摘BACKGROUND Despite advancements,endoscopic retrograde cholangiopancreatography(ERCP)poses challenges,including the risk of post-ERCP pancreatitis and difficulty of biliary cannulation.AIM To compare dome and tapered tip sphincterotomes,focusing on their efficacy in achieving successful biliary cannulation and reducing the incidence of post-ERCP pancreatitis.METHODS In this prospective,single-blind,randomized pilot study conducted at Inha Uni-versity Hospital,85 patients undergoing ERCP were equally divided into dome and tapered tip sphincterotome groups.The co-primary outcomes were the success rate of selective biliary cannulation and incidence of post-ERCP pancre-atitis.The secondary outcomes included biliary cannulation time,number of unintended pancreatic duct access events,and total procedure time.RESULTS The success rates of selective biliary cannulation were 74.4%and 85.7%in the dome and tapered tip groups,respectively,with no significant difference(P=0.20).Similarly,the incidence of post-ERCP pancreatitis did not differ significantly between the groups(5 cases in the tapered tip group vs 6 in the dome tip group,P=0.72).However,difficult cannulation was significantly more common in the dome tip group than in the tapered tip group(P=0.05).Selective biliary cannula-tion time emerged as a significant predictor of post-ERCP pancreatitis(multivariate odds ratio=9.33,95%confi-dence interval:1.31-66.44,P=0.03).CONCLUSION This study indicated that the sphincterotome tip type does not markedly affect biliary cannulation success or post-ERCP pancreatitis rates.However,cannulation duration is a key risk factor for post-ERCP pancreatitis.These findings provide preliminary insights that highlight the importance of refining ERCP practices,including sphinc-terotome selection,while underscoring the need for larger multicenter studies to improve procedure time and patient safety.
基金National Natural Science Foundation of China(No.52006178)National Key R&D Program of China(No.Y2019-Ⅷ-0007-0168)the Fundamental Research Funds for the Central Universities and the Innovation Capacity Support Plan in Shaanxi Province of China(Grant No.2023-CX-TD-19)。
文摘Base on the standard k-ωturbulent model,numerical method for solving three dimensional Reynolds Averaged Navier-Stokes(RANS)was adopted to study the aerothermal characteristics of the turbine blade with casing relative motion.Experimental data were used to verify the effectiveness of the numerical method and turbulent model.The effect of blade tip clearance,geometry and relative motion on blade tip aerothermal characteristics were analyzed.The numerical results show that for the flat tip,relative motion can effectively suppress tip leakage and reduce leakage vortex size at rotating blade-static casing(BRCS)and static bladerotating casing(BSCR)conditions.A high level of heat transfer region can be observed near the leading edge at the conditions of rotating bladerotating casing(BRCS)and static bladestatic casing(BSCR).The blade tip heat transfer coefficient expands with the increase of tip clearance at different relative motion modes.At the brcs and bscs,the axial average heat transfer trend is the closest when the tip clearance is 1.5%H.The scraping vortex generated by relative motion at brcr and bscs inhib-its the development of leakage flow for squealer tip because of its sealing effect.High level of heat transfer region is also concentrated in the leading edge at brcr and bscs.The size of scraping vortex weakens with the increase of cavity depth.The distribution trend of the average heat transfer coefficient is similar in the two cases of relative static and relative motion,except for the case of 2.5%H cavity depth.
基金the support of National Natural Science Foundation of China(No.52006178,51936008)National Key R&D Program of China(No.Y2019-Ⅷ-0007-0168)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Innovation Capacity Support Plan in Shaanxi Province of China(Grant No.2023-CX-TD-19)。
文摘For unshrouded blade tip,the high-temperature gas flows through the tip clearance by force of the lateral pressure difference.Thereby,the blade tip endures increasing thermal load.Furthermore,the conventional blade tip treatment cannot continuously provide protection for the deteriorating service environment.In the present study,aerothermal characteristics of the squealer blade tip with staggered ribs,partial squealer rim and different partial squealer rim thickness were investigated to explore the influences of ribbed-cavity tip on the tip heat transfer,leakage flow and turbine stage efficiency.The numerical results indicate that the ribbed-cavity tips are beneficial for the reduction of the blade tip thermal load and leakage flow.Among the present six blade tip designs,the minimal area-averaged heat transfer coefficient is obtained by the case with the staggered ribs and a deeper squealer rim,which is reduced by 31.41%relative to the squealer tip.Plus,the blade tip modification closer to leading edge or tip mid-chord region performs better than trailing edge in reducing the tip leakage flow.
