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Title :リアルタイム温度場測定による非円形噴口群の衝突熱伝達特性の制御に関する研究
Title alternative :STUDY ON IMPINGEMENT HEAT TRANSFER CONTROL WITH NON-CIRCULAR DUAL JETS USING REAL TIME AND SPATIAL TEMPERATURE MEASUREMENTS
Authors :親川, 兼勇
Authors alternative :Oyakawa, Kenyu
Issue Date :Mar-1997
Abstract :平成7年度~平成8年度科学研究費補助金(基盤研究C)研究成果報告書
研究概要:衝突噴流は岐点近傍で高い局所熱伝達率を有することから物体の急冷・加熱に多く用いられている.その場合には単一の噴流ではなく複数の,とくに非円形の噴流群となる.噴流群の熱伝達特性の基礎デ-タを得るために,2個の長円形噴口より空気を噴出させ,対象平板に衝突させた場合の,両長円間の距離Sの影響を調べた.この場合の平板上の温度分布の測定には2次元アレイ型のインジウム・アンチモン(InSb)をセンサ-とする赤外線映像装置を用いた.また熱電対による温度の測定,油膜法による流れの可視化,さらに流れ場の速度および乱れ強さを測定した.得られた結果はつぎのとおりである. 1)2噴口間の距離が小さい場合S/L=1.67(S:噴口間距離,L:短軸長さ)では等温度分布線図,熱伝達率分布および油膜模様は噴口と平板間距離が小さい場合において,十字形の分布を示す.これはあたかも周方向にひずんだ1個の噴流の衝突によるようなものとなる. 2)S/L=3.33 になると,S/Lが小さい場合に噴流は衝突する前に合体し,噴流どうしの干渉となる.一方S/Lが大きくなると,噴流は衝突した後の流出流と干渉するようになる.このS/L=3.33はその中間であり,噴流同士の干渉,噴流と流出流との干渉を含むために非定常流動場となる.それにつられて熱伝達特性も非定常性を示す. 3)2噴流の場合のSwitching現象は単一噴流と比べてより下流で起こり,まず外縁より起こり,その後中央部に起こりる.温度分布,熱伝達率分布は眼鏡状の形となる. 4)赤外線映像装置は時・空間的温度分布の変化を知るのに非常に有用である.
THE IMPINGEMENT JET HAS BEEN UTILIZED FOR ENHANCING THE HEAT TRANSFER IN MANY RAPID HEATING AND COOLING SYSTEMS BECAUSE THE RELATIVELY HIGH HEAT TRANSFER COEFFICIENTS ARE OBTAINED AT THE STAGNATION REGION OF THE IMPINGING JET.MULTIPLE JET,ESPECIALLY NON-CIRCULAR MULTIPLE JETS,ARE USUALLY USED FOR PRACTICAL HEAT TRANSFER DEVICES,BUT,THE DATA OF SINGLE JET CANNOT BE DIRECTLY APPLIED TO THE CASE OF MULTIPLE JETS BECAUSE THE FLOW PATTERN THEN REFLECTS THE INTERACTION AMONG JETS AND BETWEEN JET AND SPENT FLOW.IN ORDER TO OBTAIN THE BASIC INFORMATION ON EFFECTS OF AN INTERACTION PHENOMENA ON THE LOCAL HEAT TRANSFER DISTRIBUTIONS,TWO AIR JETS WERE IMPINGED TO THE TARGET PLATE.THE EFFECT OF NOZZLE-TO-NOZZLE SPACINGS ON THE HEAT TRNASFER CHARACTERISTICS OVER THE TARGET PLATE WERE EXPERIMENTALLY INVESTIGATED WHEN THE DUAL JETS ISSUING FROM THE NON-CIRCULAR ELLIPTIC NOZZLE CONFIGURATION STRUCK THE TARGET PLATE.TO MEASURE THE TIME AND SPATIAL THERMAL DISTRIBUTIONS OVER THE PLATE,AN INFRARED RADIOMETER WITH A TWO-DIMENSIONAL ARRAY OF INDIUM-ANTIMONY (In Sb) SENSORS WAS EMPLOYED IN PRESENT EXPERIMENTS.THEN THE HEAT TRANSFER COEFFICIENTS WERE OBTAINED BY THE MEASURED TEMPERATURE PROFILE.MOREOVER,THE HEAT TRANSFER COEFFICIENTS WERE OBTAINED BY USING OTHER TEMPERATURE PROFILES MEASURED WITH THERMOCOUPLES.THE FLOW PATTERNS OF THE SURFACE WERE ALSO VISUALIZED BY THE OIL-TITANIUM (IV) OXIDE METHOD.TO CLARIFY THE BEHAVIORS IN DEVELOPING PROCESSES,THE VELOSITY AND TURBULENCE INTENSITY WERE ALSO MEASURED DOWNSTREAM FROM THE NOZZLE EXIT.THE MAIN RESULTS ARE : 1) AT THE SMALL SPACINGS S/L (S : NOZZLE-TO-NOZZLE SPACING,L : MINOR AXIS WIDTH OF ELLIPTIC NOZZLE)=1.67 ISOTHERMS ; I.E.HEAT TRANSFER COEFFICIENTS CONTOURS,AND FLOW PATTERNS SHOW THE CROSS-SHAPED PATTERN FOR A SMALL NOZZLE-TO-PLATE SEPARATIONS BECAUSE THE SPENT FLOW THROUGH THE REGION BETWEEN JETS ARE SIGNIFICANTLY STRONG. 2) AT S/L=3.33, THE FLOW BEHAVIOR FOR SMALL SEPARATIONS BECOMES UNSTEADY BECXAUSE THE FLOW ARE IMMEDIATELY AFFECTED BY THE CHANGE OF CONDITION OF A ONE JET.. 3) THE SWITCHING PHENOMENA OCCURRED AT A MORE SHORT SEPARATION FOR THE SINGLE ELLIPTIC JET.FOR DUAL JETS WITH ELLIPTIC NOZZLE,THE PHENOMENA OCCURRED AT A MORE DOWNSTEARM REGION,AT THE OUTER EDGES OF JETS AT FIRST,WHEREAFTER IT ALSO OCCURRED IN THE CENTRAL PARTS. 4) THE ISOTHEMS OF INFRARED IMAGES ARE A USEFUL WAY TO AN UNDERSTANDING THE TIME AND SPATIAL CHARACTERISTICS OF FLOW AND HEAT TRANSFER.
未公開:P.8以降(別刷論文のため)
Type Local :研究報告書
Publisher :親川兼勇
URI :http://hdl.handle.net/20.500.12000/9388
Appears in Collections:Research Report (Faculty of Engineering)

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