目前模拟试验中支架–围岩不能很好地满足强度、刚度和稳定性耦合关系,支架的多维受力特征也被忽略。为了保证试验结果的准确性和科学性,建立支架三维受力力学模型,考虑邻架挤压力和架尾推力对支架的影响,在满足支架结构稳定和受力环境...目前模拟试验中支架–围岩不能很好地满足强度、刚度和稳定性耦合关系,支架的多维受力特征也被忽略。为了保证试验结果的准确性和科学性,建立支架三维受力力学模型,考虑邻架挤压力和架尾推力对支架的影响,在满足支架结构稳定和受力环境与现场支架相似的基础上,借助高精度应力/位移传感器实时获取了模型支架工作参数,研制模拟试验液压支架及测控系统,测试成套系统的性能,结果表明:两柱掩护式模型支架阻力范围0.046~0.528 k N,可以通过调整液压系统油压输出端压力和立柱内径实现额定工作阻力的输出;支架增阻阶段刚度基本不变,且承载动压冲击的能力较强;支架临界下滑角在三向受力下比单向压缩时要小,抗滑能力下降,但架间挤压力与架尾推力在一定程度上又抑制了其倾倒的发生。将模型支架应用于绿水洞煤矿3132工作面开采试验中,支架的工作阻力为22.42 MPa,与实测结果误差在5%以内。对采空区进行探测,模型支架与现场支架在调整围岩结构和应力场方面效能一致。展开更多
The ultrasonic spray technology is studied by the method of theoretical derivation, CFD simulation, spray particle diameter detection and analysis, and experimental analysis. And the ultrasonic spray process for the c...The ultrasonic spray technology is studied by the method of theoretical derivation, CFD simulation, spray particle diameter detection and analysis, and experimental analysis. And the ultrasonic spray process for the coating of vascular stent is also optimized. Firstly, the ultrasonic atomization physical model is established and the equation of atomization particle diameter is derived. Secondly, the ultrasonic atomization process is simulated by the CFD method, and shows three atomization patterns： incomplete atomization pattern, critical atomization pattern and jet atomization pattem. The critical amplitude and power equation for ultrasonic atomization is derived. Thirdly, experiment is conducted to study the influence of parameters including power, gas pressure, and surface tension. The results show that the spray is stable though few particles are likely to collide each other during spray moving, and the droplet diameter is about 10μm. The Rosin-Rammler distribution equation for ultrasonic spray is created, and the uniform index number is between 7.11 and 11.48. The uniformity of spray particle diameter, the efficiency of adjustment and the energy consumption are better than traditional spray technology. Lastly, the ultrasonic spray process parameters for stent coating are optimized to eliminate the common defects and obtain fine coating.展开更多
文摘目前模拟试验中支架–围岩不能很好地满足强度、刚度和稳定性耦合关系,支架的多维受力特征也被忽略。为了保证试验结果的准确性和科学性,建立支架三维受力力学模型,考虑邻架挤压力和架尾推力对支架的影响,在满足支架结构稳定和受力环境与现场支架相似的基础上,借助高精度应力/位移传感器实时获取了模型支架工作参数,研制模拟试验液压支架及测控系统,测试成套系统的性能,结果表明:两柱掩护式模型支架阻力范围0.046~0.528 k N,可以通过调整液压系统油压输出端压力和立柱内径实现额定工作阻力的输出;支架增阻阶段刚度基本不变,且承载动压冲击的能力较强;支架临界下滑角在三向受力下比单向压缩时要小,抗滑能力下降,但架间挤压力与架尾推力在一定程度上又抑制了其倾倒的发生。将模型支架应用于绿水洞煤矿3132工作面开采试验中,支架的工作阻力为22.42 MPa,与实测结果误差在5%以内。对采空区进行探测,模型支架与现场支架在调整围岩结构和应力场方面效能一致。
基金supported by the National Natural Science Foundation of China (Grant No. 91023024)the Technology Supported Research Program from Jiangsu Province (Grant Nos.BE2009054,BA2009002,and BK2010398)
文摘The ultrasonic spray technology is studied by the method of theoretical derivation, CFD simulation, spray particle diameter detection and analysis, and experimental analysis. And the ultrasonic spray process for the coating of vascular stent is also optimized. Firstly, the ultrasonic atomization physical model is established and the equation of atomization particle diameter is derived. Secondly, the ultrasonic atomization process is simulated by the CFD method, and shows three atomization patterns： incomplete atomization pattern, critical atomization pattern and jet atomization pattem. The critical amplitude and power equation for ultrasonic atomization is derived. Thirdly, experiment is conducted to study the influence of parameters including power, gas pressure, and surface tension. The results show that the spray is stable though few particles are likely to collide each other during spray moving, and the droplet diameter is about 10μm. The Rosin-Rammler distribution equation for ultrasonic spray is created, and the uniform index number is between 7.11 and 11.48. The uniformity of spray particle diameter, the efficiency of adjustment and the energy consumption are better than traditional spray technology. Lastly, the ultrasonic spray process parameters for stent coating are optimized to eliminate the common defects and obtain fine coating.
