井下自激脉冲射流增能装置设计及其射流冲击特性

Design and jet impingement characteristics of downhole self⁃excited pulsed jet energy⁃enhancing device

利用流体附壁效应,结合涡流能量转向冲击和反馈通道强制转向原理,研制出一种新型井下自激脉冲射流增能装置.采用控制变量法对装置的结构参数进行数值模拟,分析了不同结构和运行参数下脉冲射流的冲击特性,并制作样机,进行室内试验.研究结果表明:进出口直径比为0.71~1.18时,形成的脉冲效果良好,随着进出口直径比的增大,脉冲频率呈增大趋势,脉动压力振幅则呈现下降趋势,最大压力振幅为10.20 MPa;随着分流板喷距的增大,脉冲频率呈先增大后减小趋势,脉动压力振幅呈先减小后增大趋势;随着反馈通道截面比的增加,脉冲频率逐渐增大,而脉动压力振幅基本保持不变;涡流换向圆直径的变化对脉冲频率和脉动压力振幅影响较小;脉冲频率随来流雷诺数的增大而增大,雷诺数大于3.56×10^(5)时频率基本不再增大,但脉动压力振幅随来流雷诺数的增大而不断增大.

Combined with the principle of eddy current energy steering impact and feedback channel forced steering,the wall attachment effect was used to develop a new type of downhole self⁃excited pulsed jet energy⁃enhancing device.The structure parameters of the device were numerically simulated by the control variable method,and the pulsation characteristics of the pulsed jet for different structures and operating parameters were analyzed.A prototype was fabricated and tested in the laboratory.The research results show that when the ratio of inlet to outlet diameter is 0.71-1.18,the pulse effect is good.With the increasing of ratio of inlet to outlet diameter,the pulse frequency shows increasing trend,and the pulsating pressure amplitude shows downward trend with the maximum pressure amplitude of 10.20 MPa.With the increasing of spray distance of manifold,the pulse frequency is increased firstly with latter decreasing,while the pulsating pressure amplitude is decreased firstly with latter increasing.With the increasing of feedback channel cross⁃section ratio,the pulse frequency is gradually increased,while the pressure amplitude remains basically unchanged.The diameter change of the eddy current commutation circle has little effect on pulse frequency and pulsating pressure amplitude.The pulse frequency is increased with the increasing of Reynolds number of incoming flow.When Reynolds number is greater than 3.56×10^(5),the frequency basically no longer increases.The amplitude of pulsating pressure is increased with the increasing of Reynolds number of incoming flow.