计算机与应用化学
計算機與應用化學
계산궤여응용화학
COMPUTERS AND APPLIED CHEMISTRY
2013年
7期
721-724
,共4页
粉煤灰%空气%传热%数值模拟
粉煤灰%空氣%傳熱%數值模擬
분매회%공기%전열%수치모의
fly ash%air%heat transfer%numerical simulation
近年来国内外竞相开展利用粉煤灰等制备保温材料的研发工作，以粉煤灰传热为研究对象，对粉煤灰内的流场、温度场、高温壁面平均努谢尔数Nu进行研究；采用整场求解法方法进行数值求解，对网格的独立性和计算过程进行了验证；得到了粉煤灰传热一些基本数据，分析了粉煤灰温度场和流场随瑞利数Ra的变化规律。研究结果表明：随着Ra增加，开始流线均匀分布为一个顺时针大窝，逐渐变化为流线集中分布在流场外侧，而在中央基本上保持静止状态；当Ra很小时，无量纲等值线近似于平行高低温壁面的垂直线，随着Ra数逐渐增大，对应的温度等值线近似呈高温至低温的线性变化趋势；Ra小于105时，高温壁面Nu基本为2.37~3.31的定值；高温壁面底部努谢尔数Nu数大，最大值为30.8，上部Nu数小，最小值为1.19。
近年來國內外競相開展利用粉煤灰等製備保溫材料的研髮工作，以粉煤灰傳熱為研究對象，對粉煤灰內的流場、溫度場、高溫壁麵平均努謝爾數Nu進行研究；採用整場求解法方法進行數值求解，對網格的獨立性和計算過程進行瞭驗證；得到瞭粉煤灰傳熱一些基本數據，分析瞭粉煤灰溫度場和流場隨瑞利數Ra的變化規律。研究結果錶明：隨著Ra增加，開始流線均勻分佈為一箇順時針大窩，逐漸變化為流線集中分佈在流場外側，而在中央基本上保持靜止狀態；噹Ra很小時，無量綱等值線近似于平行高低溫壁麵的垂直線，隨著Ra數逐漸增大，對應的溫度等值線近似呈高溫至低溫的線性變化趨勢；Ra小于105時，高溫壁麵Nu基本為2.37~3.31的定值；高溫壁麵底部努謝爾數Nu數大，最大值為30.8，上部Nu數小，最小值為1.19。
근년래국내외경상개전이용분매회등제비보온재료적연발공작，이분매회전열위연구대상，대분매회내적류장、온도장、고온벽면평균노사이수Nu진행연구；채용정장구해법방법진행수치구해，대망격적독립성화계산과정진행료험증；득도료분매회전열일사기본수거，분석료분매회온도장화류장수서리수Ra적변화규률。연구결과표명：수착Ra증가，개시류선균균분포위일개순시침대와，축점변화위류선집중분포재류장외측，이재중앙기본상보지정지상태；당Ra흔소시，무량강등치선근사우평행고저온벽면적수직선，수착Ra수축점증대，대응적온도등치선근사정고온지저온적선성변화추세；Ra소우105시，고온벽면Nu기본위2.37~3.31적정치；고온벽면저부노사이수Nu수대，최대치위30.8，상부Nu수소，최소치위1.19。
In recent years, researches and development works on making thermal insulation material with fly ash and others are competitively launched at home and abroad. Heat transfer of fly ash is the object of study. The flow field, temperature field and average Nusselt numbers Nu of the high temperature wall surface in the fly ash are studied. Numerical solution is carried out using whole field solving method. The grid independence and computation process are verified. Some basic data is obtained and the change of temperature field and flow field of fly ash with Rayleigh number Ra is analyzed. The results of the study show that: with the increase of Ra , at first the flow lines are uniformly distributed as a clockwise big nest, gradually the flow lines are concentrated in the outer side of the flow field, while in the centre they remain mainly stationary state;When Ra is very small, non-dimensional contours approximately parallel the vertical line of wall surface of the high and low temperature, with the gradually increase of Ra , the corresponding temperature contours approximately forms as the linear trend of the high temperature to the low temperature;When Ra is less than 105, Nu of the high temperature wall surface is a constant value of 2.37 to 3.31; Nu of the bottom of high temperature wall surface is large, the maximum value is 30.8, Nu of the upper part is small, the minimum value is 1.19.
