This work studies the turbulent drag reduction(TDR)effect of a flat plate model using a spanwise slot blowing pulsed plasma actuator(SBP-PA).Wind tunnel experiments are carried out under a Reynolds number of 1.445...This work studies the turbulent drag reduction(TDR)effect of a flat plate model using a spanwise slot blowing pulsed plasma actuator(SBP-PA).Wind tunnel experiments are carried out under a Reynolds number of 1.445×10^(4).Using a hot-wire anemometer and an electrical data acquisition system,the influences of millisecond pulsed plasma actuation with different burst frequencies and duty cycles on the microscale coherent structures near the wall of the turbulent boundary layer(TBL)are studied.The experimental results show that the SBP-PA can effectively reduce the frictional drag of the TBL.When the duty cycle exceeds 30%,the TDR rate is greater than 11%,and the optimal drag reduction rate of 13.69%is obtained at a duty cycle of 50%.Furthermore,optimizing the electrical parameters reveals that increasing the burst frequency significantly reduces the velocity distribution in the logarithmic region of the TBL.When the normalized burst frequency reaches f+=2πf_(p)d/U_(∞)=7.196,the optimal TDR effectiveness is 16.97%,indicating a resonance phenomenon between the pulsed plasma actuation and the microscale coherent structures near the wall.Therefore,reasonably selecting the electrical parameters of the plasma actuator is expected to significantly improve the TDR effect.展开更多
针对塔里木盆地台盆区超深小井眼定向钻井机械钻速低、钻头使用寿命短、常规螺杆钻具脱胶脱扣、钻井液稳定性差和产层喷漏同存等难题,研究形成了塔里木盆地超深小井眼定向钻井提速提效关键技术。以标准行程钻速和钻头进尺为指标,采用统...针对塔里木盆地台盆区超深小井眼定向钻井机械钻速低、钻头使用寿命短、常规螺杆钻具脱胶脱扣、钻井液稳定性差和产层喷漏同存等难题,研究形成了塔里木盆地超深小井眼定向钻井提速提效关键技术。以标准行程钻速和钻头进尺为指标,采用统计分析法优选了适用于目的层的ϕ149.2 mm/ϕ165.1 mm KS1352DGRX型钻头和ϕ120.7 mm KDM1062TR型钻头;对比国内外抗高温螺杆现状,确定了井底温度低于180℃时推荐使用国产抗高温螺杆,高于180℃时推荐使用全金属螺杆或进口耐高温螺杆;采用理论分析结合数值模拟的方法,优化设计了小尺寸降摩减阻工具,并优化了其安放位置;优选抗盐高温高压降滤失剂和抑制剂,研选除氧剂等,制定合理pH值调控和钙离子补充措施,形成了抗温200℃钻井液;分析了顺北油气田产层钻进喷漏同层的特点,确定了“降密度+井口控压+优化排量”的井控基本原则。塔里木盆地5口井应用了超深小井眼定向钻井提速提效关键技术,小井眼段平均机械钻速提高了113.24%,平均井径扩大率5.57%,平均钻井周期缩短了35.03%,均未发生井下故障和复杂情况。超深小井眼定向钻井提速提效技术为塔里木盆地勘探开发提供了技术支撑。展开更多
基金supported by National Natural Science Foundation of China(Nos.61971345 and 12175177)the Foundation for Key Laboratories of National Defense Science and Technology of China(No.614220120030810).
文摘This work studies the turbulent drag reduction(TDR)effect of a flat plate model using a spanwise slot blowing pulsed plasma actuator(SBP-PA).Wind tunnel experiments are carried out under a Reynolds number of 1.445×10^(4).Using a hot-wire anemometer and an electrical data acquisition system,the influences of millisecond pulsed plasma actuation with different burst frequencies and duty cycles on the microscale coherent structures near the wall of the turbulent boundary layer(TBL)are studied.The experimental results show that the SBP-PA can effectively reduce the frictional drag of the TBL.When the duty cycle exceeds 30%,the TDR rate is greater than 11%,and the optimal drag reduction rate of 13.69%is obtained at a duty cycle of 50%.Furthermore,optimizing the electrical parameters reveals that increasing the burst frequency significantly reduces the velocity distribution in the logarithmic region of the TBL.When the normalized burst frequency reaches f+=2πf_(p)d/U_(∞)=7.196,the optimal TDR effectiveness is 16.97%,indicating a resonance phenomenon between the pulsed plasma actuation and the microscale coherent structures near the wall.Therefore,reasonably selecting the electrical parameters of the plasma actuator is expected to significantly improve the TDR effect.
文摘针对塔里木盆地台盆区超深小井眼定向钻井机械钻速低、钻头使用寿命短、常规螺杆钻具脱胶脱扣、钻井液稳定性差和产层喷漏同存等难题,研究形成了塔里木盆地超深小井眼定向钻井提速提效关键技术。以标准行程钻速和钻头进尺为指标,采用统计分析法优选了适用于目的层的ϕ149.2 mm/ϕ165.1 mm KS1352DGRX型钻头和ϕ120.7 mm KDM1062TR型钻头;对比国内外抗高温螺杆现状,确定了井底温度低于180℃时推荐使用国产抗高温螺杆,高于180℃时推荐使用全金属螺杆或进口耐高温螺杆;采用理论分析结合数值模拟的方法,优化设计了小尺寸降摩减阻工具,并优化了其安放位置;优选抗盐高温高压降滤失剂和抑制剂,研选除氧剂等,制定合理pH值调控和钙离子补充措施,形成了抗温200℃钻井液;分析了顺北油气田产层钻进喷漏同层的特点,确定了“降密度+井口控压+优化排量”的井控基本原则。塔里木盆地5口井应用了超深小井眼定向钻井提速提效关键技术,小井眼段平均机械钻速提高了113.24%,平均井径扩大率5.57%,平均钻井周期缩短了35.03%,均未发生井下故障和复杂情况。超深小井眼定向钻井提速提效技术为塔里木盆地勘探开发提供了技术支撑。
