戈壁近地表粉尘释放动力机制的野外风洞试验

Study on dynamic mechanism of dust emission from gobi based a portable wind tunnel experiment atop the Mogao Grottoes,Dunhuang,China

跃移沙粒的轰击是戈壁地表粉尘释放的主要动力机制。以往对戈壁粉尘释放的包括风洞试验及野外监测的研究,由于高频测量仪器与试验方法的欠缺,无法定量化跃移沙粒能量等因素对戈壁地表粉尘释放的影响。本研究采用野外风洞,利用Sensit传感器对跃移沙粒不同能量过程进行测定,研究不同供沙条件下的戈壁近地表(0~20 cm)范围内的粉尘变化规律与地表粉尘释放动力机制。结果表明:跃移沙粒轰击作用是戈壁地表粉尘释放主要因素,也是评估粉尘释放程度的重要指征;跃移沙粒的反弹能量与粉尘释放通量相关性最强,冲击能量次之,5 cm高度撞击能量相关性最小,表明跃移沙粒轰击形成的冲击及反弹能量的转化是粉尘释放的一个重要动力过程。

Impacting splash of saltating particles is the main dynamic mechanism of dust emission from gobi.However,due to the lack of high frequency measuring instruments and experimental methods,previous studies on gobi dust emission including wind tunnel experiments and field observation can not accurately and quantitatively study the impact of the energy of saltatingsand on the dust emission from gobi.In this study,the field wind tunnel experiments method was used to study the dynamic mechanism of the dust variation law in the near surface(0-20 cm)of the gobi and the dynamic mechanism of dust emission,and the different energy processes of saltating sand were measured by Sensit sensor.The results show that bombardment of saltating sands is one of the main factors of dust emission near surface of gobi and an important factor to assess the dust emission.Rebounding energy has the best correction with dust emission flux,followed by surface impact energy,and impact energy at 5cm above the ground has the weakest correction.It shows that the saltating sand bombardment and the conversion of impact energy and rebounding energy is an important dynamic process of dust emission.