報告書番号

383012

タイトル（和文）

２次元プレナム内の乱流計測と２方程式乱流モデルによる解析

タイトル（英文）

TURBULENCE MEASUREMENTS IN A PLENUM AND NUMERICAL SIMULATIONS USING TWO-EQUATION TURBULENCE MODEL

概要 （図表や脚注は「報告書全文」に掲載しております）

タンク型ＦＢＲでは，原子炉容器内にポンプや中間熱交換器等が配置されているため，炉心から噴出する高温の冷却材は，ホットプレナム内で混合しながらこれらの間を複雑に流れる。この場合，冷却材は原子炉容器壁やこれらの構造物の材料表面に温度変動に及ぼすことが考えられる。とくに，わが国のような厳しい耐震条件下では，構造が厚肉となることが予想されるため，変動熱応力に伴う構造材の疲労を防ぐことは重要な課題である。ここでは，構造材表面への温度変動を評価するに当り，まず必要となる炉心噴出流の混合現象を把握する目的で，ホットプレナム内の流況と流速変動（乱流と呼ばれる）の計測法とその解析法を検討した。

概要 （英文）

THE MOST IMPORTANT PROBLEM IN THE THERMAL HYDRAULIC DESIGNS OF THE POOL-TYPE FBR IS TO ESTIMATE THE THERMAL CONDITIONS AFFECTING THE VESSEL OR INTERNAL STRUCTURES DURING BOTH STEADY AND TRANSIENT OPERATIONS.THE SEVERITY OF THESE CONDITIONS IN THE JAPANESE POOL-TYPE REACTOR WHICH WILL BE REINFORCED AND EQUIPPED WITH SPECIAL DEVICES FOR ASEISMIC DEMANDS ARE APT TO BE MUCH GREATER THAN OTHER COUNTRIES.WATER TESTS AND THERMAL HYDRAULIC ANALYSES,THEREFORE,HAVE BEEN PERFORMED TO STUDY SUCH CONDITIONS. THE RESULTS OF TURBULENCE MEASUREMENTS AND THEIR NUMERICAL ANALYSES FOR THE WATER TEST ARE DESCRIBED HERE TO STUDY THE FLOW PATTERN AND TURBULENT CHARACTERISTICS IN A PLENUM.FIRST OFALL,MOST SIMPLE GEOMETRY IS TAKEN UP FOR THE SHAPE OF THE PLENUM.IT ISSIMPLIFIED IN A RECTANGLE. THE LENGTH IS 52CM,HEIGHT IS 45CM AND WIDTHIS 10CM,SO THAT THE FLOW BECOMES QUOSI-TWO-DIMENSIONAL.IT IS EXPEDIENTFOR MEASUREMENTS AND ANALYSES. THE TURBULENCE MEASUREMENTS FOR THE FLOW IN THE PLENUM ARE PERFORMED WITH A LASER-DOPPLER ANEMOMETER(LDA).A TURBULENCE MODEL IS USED HERE AS AN ANALYTICAL MODEL TO ANALYZE AND COMPARE WITH THE EXPERIMENTAL RESULTS. A SPECIAL TWO EQUATION MODEL,THAT IS CALLED (K-SIGMA) MODEL IS ADOPTED HERE.WHERE,K IS TURBULENT KINEMATIC ENERGY AND SIGMA IS TURBULENT VISCOSITY.THE (K-SIGMA) MODEL HAS BEEN DEVELOPED AND ISSUED BY AMERICAN DOE(DEPARTMENT OF ENERGY) TO ESTIMATE THETHERMAL HYDRAULICS IN THE CLINCH RIVER BREEDER REACTOR(PROTOTYPE FBR,USA). CONSEQUENTLY,IT IS CONFIRMED HERE THAT LDA AND THE (K-SIGMA) MODELARE AVAILABLE FOR MAKING CLEAR THE TURBULENT PHENOMENA.ESPECIALLY,RESULTS OF TIME AVERAGED VELOCITIES AS WELL AS TURBULENT QUANTITIES(REYNOLDS STRESSES) ANALYZED BY THE TURBULENCE MODEL AGREE WELL WITH EXPERIMENTAL RESULTS OBTAINED BY LDA.

報告者

キーワード