中文摘要：

水环境污染问题是当今世界各国所普遍关注的重大问题．城市污水，热电、核电厂的冷却水排放过程都与射流有关，因此，研究各种污水处理工程中排放口附近的流动特性具有重要的理论和实际意义．利用声学多普勒流速仪（ADV）测速系统和数字温度仪研究了同向三圆孔热水浮力射流的排放特性，得到了流速和温度的分布、不同孔间距和流速比的射流轨迹线、射流中轴线上的速度和温度衰减，探讨了相对孔间距和流速比对多孔浮力射流流动变化特性的影响，实验和数值模拟反映的变化规律相一致，射流轴线速度和温度衰减变化明显的区域主要集中在80～90倍的射流直径范围内；射流温度相同时，流速比越大，中轴线上温度和速度衰减越快，射流轨迹线向上抬升的趋势越小；孔间距越小，射流轨迹线向上抬升的趋势越明显．

英文摘要：

Water environmental pollution is a widely attended important problem. The discharge quantity of city sewage and power plant cooling water, etc. is increasing gradually. Because the discharge process is related with jet behavior, it is significant to study the flow behavior near the discharge outlet of the sewage treatments building in theoretical research and practical application. By using Acoustic Doppler Velocimeter （ADV） technique and digital thermometer measurement techniques, the characteristics of multi-ports thermal buoyant jet in co-flowing surroundings are studied in this paper. By use of the special WinADV software, several characteristics are acquired, such as the profiles of velocity and temperature, the jet trajectory of different pipe spacings and velocity ratio, as well as temperature attenuation and velocity attenuation on the axis. Furthermore, the influence of relative pipe spacing and velocity ratio on flow characteristics are discussed. All the results are compared with the numerical simulation results.