沙粒体积浓度能够反映风沙流中运动沙粒在空间中的疏密程度。本文采用风洞实验和理论分析相结合的方法研究沙粒体积浓度的分布规律。首先，对平均粒径分别为0.23mm和0.15mm的两组沙样在风洞中采用PIV测量技术与集沙仪相结合的方式测量获得与沙粒体积浓度存在着函数关系的参数（即沙粒个数、输沙通量、沙粒平均水平速度），然后采取两种计算方法得出沙粒体积浓度随高度的变化规律；其次根据已有风沙流模型的研究思想，建立了预测沙粒体积浓度的数学模型，将实验参数或经验值代入模型来预测沙粒体积浓度；最后将模型计算结果与实验结果进行对比，考察模型的可靠性。　　　方法一采用PIV测量系统所拍摄的沙粒图像信息，统计沙粒个数进一步计算沙粒体积浓度，得出沙粒体积浓度在较高高度处呈指数规律衰减，而在较低高度处偏离上部指数规律增加；不同风速时，在较高高度处沙粒体积浓度的指数衰减速率不同，表现为主流风速越大，沙粒体积浓度随高度衰减越慢，反之，主流风速越小，沙粒浓度随高度的衰减越快；在相同高度处，沙粒体积浓度随着风速的增大而增大；沙粒的跃移主要发生在距沙床面的0.1m高度内，床面处沙粒体积浓度的数量级在10-4至10-3范围内。方法二通过集沙仪获得的输沙通量和PIV测量所得的沙粒平均水平速度来计算沙粒体积浓度，得出沙粒体积浓度随高度的变化基本符合指数衰减规律。对于平均粒径0.23mm的沙粒，方法一和方法二所得的沙粒体积浓度规律基本一致，而对于平均粒径0.15mm的沙粒，在小于0.03m的高度两种方法求得的沙粒体积浓度基本一致，在较高的高度（h>0.03m），方法二求得的沙粒体积浓度比方法一求得的值要小，可能原因是方法一中计算所用的平均粒径大于该高度处的实际平均粒径。　　　沙粒体积浓度的数学模型中沙粒运动只考虑重力和拖曳力的作用，床面起跳沙粒的水平速度和垂直速度分别采用正态分布和指数分布函数来描述，根据稳态风沙流中运动沙粒的动态平衡特征可推导计算沙粒体积浓度。将实验得出的相关参数或以往研究的常用经验值代入所建数学模型，得到稳态风沙流中粒体积浓度的垂向变化规律基本为负指数衰减分布。将模型计算结果与实验结果对比，发现平均粒径为0.23mm的沙样二者结果吻合很好；平均粒径为0.15mm的沙样在较低高度处（h<0.03m）二者结果也基本吻合，而在较高高度处模拟的沙粒体积浓度小于本文实验值，可能原因是计算模型做了许多简化，不能反映该实际沙样的一些特征。　　　本文实验为风沙流研究提供了大量实验数据，所建沙粒体积浓度的数学模型也为风沙流模型研究提供了一个思路，在以后的研究中可引入其他影响因素进一步提高模型对沙粒体积浓度的预测精度。

The particle volume concentration can reflect the extent of concentration of sand particles in space during aeolian sand movement. In this thesis, the characteristics of particle volume concentration are analyzed by wind tunnel experiments and theoretical analysis. Firstly, by using PIV measurement technology and the sand sampler, the parameters (i.e., particle number, sand mass flux and mean particle horizontal velocity) related to particle volume concentration are obtained for the two groups of sand particles with mean diameter of 0.23mm and 0.15mm, respectively, then the particle volume concentration is calculated by two methods. Secondly, according to the ideas of the published models of aeolian sand transport, a mathematical model for particle volume concentration is built, and the particle volume concentration is simulated by setting the reasonable input parameters of the model according to the experimental parameters and empirical values. Lastly, the comparison between the model and experiment is done and the reliability of the model is also analyzed.　　　The first method is that the particle volume concentration in the vertical direction is calculated by particle counting according to the image information captured by PIV measuring system. The results show that at the higher height, the particle volume concentration decreases exponentially with the increase of height, while at the lower height, the variation of particle volume concentration with height deviates from upper exponential law. The decay rate of the particle volume concentration is different at different wind velocity. The particle volume concentration decays slower with height at higher wind velocity, and faster at lower wind velocity. At the same height, the particle volume concentration increases with the increase of the wind velocity, and the sand saltation mainly occurs within the 0.1 m height above the sand bed surface. The particle volume concentration ranges from 10-4 to 10-3. The second method is that the particle volume concentration is obtained through the sand mass flux from the sand sampler and the mean horizontal velocity of the moving particles from the PIV images. The results show that the particle volume concentration generally decays exponentially with the increase of height. For the sand particles with the average diameter of 0.23 mm, the variation of the particle volume concentration with height from the two methods is similar. For the sand particles with the average diameter of 0.15 mm, the variation of the particle volume concentration with height from the two methods is similar below the height of about 0.03 m, while the particle volume concentration obtained by the second method is smaller than that by the first method at the higher height (h>0.03 m). The probable reason is that the mean particle diameter used in the first method is larger than the actual mean diameter at the higher height.