Flow field around a bathtub vortex in a cylindrical vessel was measured. A gas core of the bathtub vortex was stationarily formed at the center of the vessel. An inlet open channel and an outlet pipe were equipped at the top tangentially and at the bottom center, respectively. Flow field was visualized using ink tracer or particle tracers, resulting in the velocity distribution measured. The downward velocity in the central region was found to be proportional to the distance from the original surface without the gas core except in the neighborhood of the outlet. Using the Laser Doppler Velocimeter, radial distribution of the downward velocity in the vessel was measured. The velocity distribution in the central region was found to be very complex. In the lower flow rate condition, the highest velocity position was the center. However, with increasing the flow rate, the highest position moved to outside. The inside of the central region was almost stagnant. The flow rate through the central region was 10 ∼ 50 % of the total flow rate. Formation of the stagnant region was related to the determination of the downward velocity gradient.
{"title":"Study on the Flow Distribution Around a Bathtub Vortex in a Cylindrical Vessel","authors":"S. Sakai, H. Madarame, K. Okamoto","doi":"10.1115/imece1997-0610","DOIUrl":"https://doi.org/10.1115/imece1997-0610","url":null,"abstract":"\u0000 Flow field around a bathtub vortex in a cylindrical vessel was measured. A gas core of the bathtub vortex was stationarily formed at the center of the vessel. An inlet open channel and an outlet pipe were equipped at the top tangentially and at the bottom center, respectively. Flow field was visualized using ink tracer or particle tracers, resulting in the velocity distribution measured. The downward velocity in the central region was found to be proportional to the distance from the original surface without the gas core except in the neighborhood of the outlet. Using the Laser Doppler Velocimeter, radial distribution of the downward velocity in the vessel was measured. The velocity distribution in the central region was found to be very complex. In the lower flow rate condition, the highest velocity position was the center. However, with increasing the flow rate, the highest position moved to outside. The inside of the central region was almost stagnant. The flow rate through the central region was 10 ∼ 50 % of the total flow rate. Formation of the stagnant region was related to the determination of the downward velocity gradient.","PeriodicalId":49736,"journal":{"name":"Nuclear Engineering International","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88272716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present experiment is conducted to study the nonuniform heat transfer of single-phase water turbulent flow and two-phase steam-water flow in horizontal helical coils tubes. The inner and the outer diameter of the tube are 11mm and 15mm respectively, and the ratio of the diameter of the coil to that of the tube is 23.27. The experimental pressure ranges from 0.5 to 3.0MPa, mass flowrate from 200 to 2500 kg/m2 s, heat flux from 230 to 500kW/m2, and the maximum exit steam quality 0.86. Along both the tube axial direction and the periphery on the cross-section, the local heat transfer coefficients are not evenly distributed. The secondary flow has less contribution to the enhancement heat transfer of the coil with increasing Reynolds number to a high level. Taking the average coefficient at outlet section as that of the coil is not reasonable.
{"title":"Nonuniform Heat Transfer in Horizontal Helical Coils Tube Steam Generators","authors":"B. Bai, Liejin Guo, Xuejun Chen","doi":"10.1115/imece1997-0613","DOIUrl":"https://doi.org/10.1115/imece1997-0613","url":null,"abstract":"\u0000 The present experiment is conducted to study the nonuniform heat transfer of single-phase water turbulent flow and two-phase steam-water flow in horizontal helical coils tubes. The inner and the outer diameter of the tube are 11mm and 15mm respectively, and the ratio of the diameter of the coil to that of the tube is 23.27. The experimental pressure ranges from 0.5 to 3.0MPa, mass flowrate from 200 to 2500 kg/m2 s, heat flux from 230 to 500kW/m2, and the maximum exit steam quality 0.86.\u0000 Along both the tube axial direction and the periphery on the cross-section, the local heat transfer coefficients are not evenly distributed. The secondary flow has less contribution to the enhancement heat transfer of the coil with increasing Reynolds number to a high level. Taking the average coefficient at outlet section as that of the coil is not reasonable.","PeriodicalId":49736,"journal":{"name":"Nuclear Engineering International","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86980704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One advanced nuclear reactor design has a residual heat removal (RHR) pipe connected to the bottom of a steam generator outlet plenum. The water in the plenum can become thermally stratified during postulated loss of coolant accidents. Cold water injected through the RHR pipe has the potential effect of increasing the steam condensation on the pool surface due to the stirring action of the jet. The amount of increase depends on a number of factors, including the jet velocity and the pool height above the jet injection point. Prediction of steam condensation rates, before and after the jet breaks the pool surface, is the topic of this paper. Data and correlations exist for pre surface breakthrough and a method has been developed for post breakthrough. The models have been incorporated into the reactor safety analysis computer software known as RELAP5 (1995). Comparisons of predictions against data are presented.
{"title":"Condensation Enhancement on a Pool Surface Caused by a Submerged Liquid Jet","authors":"R. Shumway","doi":"10.1115/imece1997-0602","DOIUrl":"https://doi.org/10.1115/imece1997-0602","url":null,"abstract":"\u0000 One advanced nuclear reactor design has a residual heat removal (RHR) pipe connected to the bottom of a steam generator outlet plenum. The water in the plenum can become thermally stratified during postulated loss of coolant accidents. Cold water injected through the RHR pipe has the potential effect of increasing the steam condensation on the pool surface due to the stirring action of the jet. The amount of increase depends on a number of factors, including the jet velocity and the pool height above the jet injection point. Prediction of steam condensation rates, before and after the jet breaks the pool surface, is the topic of this paper. Data and correlations exist for pre surface breakthrough and a method has been developed for post breakthrough. The models have been incorporated into the reactor safety analysis computer software known as RELAP5 (1995). Comparisons of predictions against data are presented.","PeriodicalId":49736,"journal":{"name":"Nuclear Engineering International","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72758286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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