对水垫塘内淹没射流流场特性的研究, 过去多采用介入流场中的单点测量技术或涡黏性各向同性假设的紊流 数值模拟的方法, 无法获得其全域瞬时精细流场。利用非介入的粒子成像测速技术( PIV) 对水垫塘内斜向淹没射 流的紊流流场特性进行了研究。试验结果显示, 利用 PIV 技术可获得含有大量瞬时性随机涡的精细流场结构, 射 流与水体间的剪切和混掺使流速减小、 紊动能产生和水体涡旋运动, 是能量传递和耗散的主要机制; 射流流量沿程 增加, 流速沿程减小, 涡量值减小; 在淹没射流区, 流速、 紊动能和涡量值沿射流轴线近似对称分布, 但射流下游侧的 流速、 紊动能和涡量均稍比上游侧稍高, 下游水体紊动相对剧烈, 而上游水体则相对平稳; 在附壁射流区, 射流与上 层水体剪切、 混掺剧烈, 形成近似淹没水跃的流态, 射流流量沿流向继续增加, 流速、 紊动能及涡量值均沿水垫塘竖 向和水平方向减小。

In the past, the point measurement techniques, such as laser Doppler velocimetry( LDV) and hot2wire anemometry, or the turbulent flow numerical model with the hypothesis of the isotropy of vortex were used to investigate the turbulent flow field in a pool with an oblique submerged jet. All these methods cannot obtain the refined structure characteristics of the instan2 taneous flow field. The particle image velocimetry(PIV) was adopt to characterize the turbulent flow field in a pool with an ob2 lique submerged jet in term of the velocity, turbulent energy, and flow vorticity. T he results indicated that( 1) the refined struc 2 ture of flow fields with instantaneous and random eddies can be obtained, and the shearing and mixing between the jet and sur2 rounding water decrease the jet velocity and produce turbulent energy and vortex motion, which is the dominant mechanism for jet energy transmission and dissipation in the pool; (2)with the jet plunging into the pool, the flow rate of jet increases along the jet path, while the flow velocity and flow vorticity decrease; ( 3) in the submerged 2jet region, the velocity, turbulent energy, and flow vorticity are approximately in symmetrical distribution. The values of velocity, turbulent energy, and flow vorticity in the jet downstream are a little higher than those in the jet upstream, indicating that the downstream water is more turbulent while the upstream water is relatively stable; and( 4) in the wall 2jet region downstream, the jet continues to shear and mix with the wa 2 ter above to form the flow pattern of a submerged hydraulic jump, and the velocity, turbulent energy, and flow vorticity decrease in both the vertical and horizontal directions.

国家自然科学基金项目( 50909067; 51009102; 51179113)