敦煌莫高窟窟内外空气交换机理研究

Research on the Air Exchange Mechanism Inside and Outside of Caves of the Mogao Grottoes,Dunhuang,China

为莫高窟洞窟安装空调系统是增加窟内外换气量、改善窟内空气品质的有效手段,其设计依据是尽量维持洞窟内微环境。为了明确窟内微环境参数及洞窟内外空气交换机理,对部分洞窟进行现场测试。通过数据分析,发现:第100窟冬季窟内外空气交换符合热压作用下单侧开口自然通风规律;但是第138窟、442窟秋季洞窟内外空气交换量与已知的热压、风压共同作用下单侧开口自然通风量计算公式不一致。利用FLUENT软件,以第328窟洞窟模型及测试数据为基础,模拟热压、风压作用下窟内外自然通风规律,量化计算公式,利用第442窟秋季现场测试数据验证公式的有效性,证明公式具有一定普适性。本研究将为莫高窟空调系统设计提供参数基础及理论保障。

The air conditioning system is an effective means to improve the air quality of caves by increasing the amount of air exchange inside and outside of the Mogao grottoes,which is designed on the premise of maintaining the microenvironment inside the caves.In order to define micro-environmental parameters and the air exchange mechanism inside and outside of the caves,tests were conducted on some of the caves.Data analysis shows that the air exchange of the 100 thcave is driven only by thermals in the winter,which the volume flow can be gained through Warren expression,while the air exchanges of the 138 thcave and the 442 thcave are driven by thermals and wind in the autumn,which the volume flow cannot be gained through the known formula.Base on the model and test data of the 328 thcave,FLUENT was used to simulate the natural ventilation law driven by thermals and wind.After quantum chemical calculation,the validity of the new expression of different pressure between in-cave and out-cave was verified with the field test data of the 442 ndcave in autumn.Also,the expression is proven to be a certain degree of universality.This study will provide parameter basis and theoretical guarantee for designing air conditioning systems for the Mogao Grottoes.