CAJ | 학술논문

为了揭示不同进口流速情况下90o方形弯管内部流动特征，在构建90o方形弯管专用PIV试验台的基础之上，对弯管内不同断面以及不同半径上的流速分布情况进行了PIV测试试验。试验结果表明：采用PIV技术能较好地获得弯管内部流动情况；流体未进入弯曲段时，各断面流速分布变化不大；而进入弯曲段后，由于受到弯管壁的约束形成旋转流动，弯管内侧流速增大，外侧流速降低；当转过60o位置后，弯管内侧流速降低，外侧流速增加；到达90o位置后，各断面的流速基本趋于一致。不同半径处的流速分布不相同，弯管内侧流速较大，外侧较小，在50o、60o处流速达到最大值；弯管不同的进口流速对于速度峰值的位置有一定的影响，而对于弯管内其他的流动情况影响较小。
위료게시불동진구류속정황하90o방형만관내부류동특정，재구건90o방형만관전용PIV시험태적기출지상，대만관내불동단면이급불동반경상적류속분포정황진행료PIV측시시험。시험결과표명：채용PIV기술능교호지획득만관내부류동정황；류체미진입만곡단시，각단면류속분포변화불대；이진입만곡단후，유우수도만관벽적약속형성선전류동，만관내측류속증대，외측류속강저；당전과60o위치후，만관내측류속강저，외측류속증가；도체90o위치후，각단면적류속기본추우일치。불동반경처적류속분포불상동，만관내측류속교대，외측교소，재50o、60o처류속체도최대치；만관불동적진구류속대우속도봉치적위치유일정적영향，이대우만관내기타적류동정황영향교소。
In order to reveal the internal flow characteristics of a 90o bending duct with square section at different inlet velocities, PIV measurements of velocity distribution were carried out for bending ducts at different sections and radii. The experimental results suggest that the flow behavior within a bending duct can be measured by PIV. Velocity profiles vary little before the fluid entering the bending section. Rotating flow forms due to the restraint of the bending wall when the fluid enters the bending section, resulting in a velocity increase at the inner wall of the bending duct and a velocity decrease at the outer wall of the bending duct. On the contrary, the velocity decreases at the inner wall of the bending duct and increases at the outer wall of the bending duct when the fluid passes through 60o. Flow velocity tends to be uniform when the fluid passes through 90o. Velocity profile was different with different radius and the velocity near the inner wall is higher than that near the outer wall. Maximum velocity occurs at 50o and 60o, and its location is found to be dependent on the inlet velocities and independent on other flow characteristics in the bending duct.