减阻剂对变截面管流动阻力特性的研究
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摘要
为探索减阻剂对变截面管水流阻力特性的影响,使用季铵盐十六烷基三甲基溴化铵作减阻剂,实验测试了该减阻剂3个质量分数的水溶液通过管径比为1∶1.49的突扩的流动阻力。研究结果表明,上游DN10管在3个质量浓度为8×10~(-5)、1.4×10~(-4)和2×10~(-4)下的临界雷诺数分别约为20 000、30 000和34 000,相应的最大减阻率分别为70%、72%和74%;而对于下游DN15管在质量浓度为8×10~(-5)时对应的临界雷诺数约为28 000,对应的最大减阻率为70%。当上游管流动雷诺数<各质量浓度对应的临界雷诺数时,突扩局部实验阻力系数<牛顿流体的理论值;当上游管流动雷诺数超过临近雷诺数后逐渐失去减阻效果时,减阻突扩流的局部实验阻力系数开始增加且大于牛顿流体的理论值。
In order to explore the effect of drag reducer on resistance characteristics flowing in a variable cross-section pipe,the resistance for three mass concentrations of drag-reducing solution flows in a sudden expanded pipe with a diameter ratio of 1∶1.49 was measured by using quaternary ammonium salt cetyltrimethyl ammonium bromide as drag reducer.The results show that the critical Reynolds numbers for upstream DN10 tube flow at three mass concentrations which are 8×10~(-5)、1.4×10~(-4) and 2×10~(-4) are about 20 000,30 000 and 34 000 respectively,and the corresponding maximum drag reduction rates are 70%,72% and 74% respectively.For downstream DN15 tube flow at 8×10~(-5),the corresponding critical Reynolds numbers are about 28 000,and the corresponding maximum drag reduction rate are 70%.For each mass concentration,as the Reynolds number of the upstream pipe flow is less than the critical Reynolds number,the sudden expansion drag coefficient is smaller than the theoretically predicted value of Newtonian fluids and increases with Reynolds number.While as the Reynolds number proceeds critical one,it is larger than that of Newton fluids and increases with increasing Reynolds numbers.
In order to explore the effect of drag reducer on resistance characteristics flowing in a variable cross-section pipe,the resistance for three mass concentrations of drag-reducing solution flows in a sudden expanded pipe with a diameter ratio of 1∶1.49 was measured by using quaternary ammonium salt cetyltrimethyl ammonium bromide as drag reducer.The results show that the critical Reynolds numbers for upstream DN10 tube flow at three mass concentrations which are 8×10~(-5)、1.4×10~(-4) and 2×10~(-4) are about 20 000,30 000 and 34 000 respectively,and the corresponding maximum drag reduction rates are 70%,72% and 74% respectively.For downstream DN15 tube flow at 8×10~(-5),the corresponding critical Reynolds numbers are about 28 000,and the corresponding maximum drag reduction rate are 70%.For each mass concentration,as the Reynolds number of the upstream pipe flow is less than the critical Reynolds number,the sudden expansion drag coefficient is smaller than the theoretically predicted value of Newtonian fluids and increases with Reynolds number.While as the Reynolds number proceeds critical one,it is larger than that of Newton fluids and increases with increasing Reynolds numbers.
引文
[1] Toms B A. Some obervations on the flow of linear polymer solutions through straight tubes at large Reynolds numbers[C]//In:Mysels M J, ed. Proceedings of the 1st International Congress on Rheology.North Holland, Amsterdam:Springer, 1948:135-138.
[2] White A. Flow Characteristics of Complex Soap Systems[J]. Nature,1967, 214(5 088):585-586.
[3] Kawaguchi Experimental Y, SegawastudynnT, Feng Z P, et al.Drag-reducing channel flow with surfactant additives-spatial structure of turbulen ceinvestigated by PIV System[J].International Journal Heat Fluid Flow, 2002, 23(5):700-709.
[4] J L Zakin, J Myska, Z Chara. New Limiting Drag Reduction and Velocity Profile Asymptotes for Non-polymeric Additives Systems[J]. AICh E Journal, 1996, 42(12):3 544-3 546.
[5]焦利芳,李凤臣,董泳,等.表面活性剂溶液在不规则管件内的湍流减阻特性[J].节能技术,2009,153(27):7-13.
[6]焦利芳.添加剂减阻技术在集中供暖系统中的节能应用[D].哈尔滨:哈尔滨工业大学,2008.
[7]焦利芳,李凤臣,苏文涛,等.表面活性剂减阻剂在集中供热系统中的应用试验研究[J].节能技术,2008,149(26):195-201.
[8]蔡书鹏,汪志能,段传伟,等.表面活性剂减阻水溶液突扩流的阻力特性[J].力学学报,2018,50(2):274-283.
[9] Usui Hiromoto, Takayasu Itoh, Takashi Saeki. On pipe diameter effects in surfactant drag-reducing pipe flows[J]. Rheol Acta,1998, 37(2):122-128.
[10]罗彬文.表面活性剂对突扩和突缩流局部阻力特性的改变研究[D].湖南:湖南工业大学,2016.
[2] White A. Flow Characteristics of Complex Soap Systems[J]. Nature,1967, 214(5 088):585-586.
[3] Kawaguchi Experimental Y, SegawastudynnT, Feng Z P, et al.Drag-reducing channel flow with surfactant additives-spatial structure of turbulen ceinvestigated by PIV System[J].International Journal Heat Fluid Flow, 2002, 23(5):700-709.
[4] J L Zakin, J Myska, Z Chara. New Limiting Drag Reduction and Velocity Profile Asymptotes for Non-polymeric Additives Systems[J]. AICh E Journal, 1996, 42(12):3 544-3 546.
[5]焦利芳,李凤臣,董泳,等.表面活性剂溶液在不规则管件内的湍流减阻特性[J].节能技术,2009,153(27):7-13.
[6]焦利芳.添加剂减阻技术在集中供暖系统中的节能应用[D].哈尔滨:哈尔滨工业大学,2008.
[7]焦利芳,李凤臣,苏文涛,等.表面活性剂减阻剂在集中供热系统中的应用试验研究[J].节能技术,2008,149(26):195-201.
[8]蔡书鹏,汪志能,段传伟,等.表面活性剂减阻水溶液突扩流的阻力特性[J].力学学报,2018,50(2):274-283.
[9] Usui Hiromoto, Takayasu Itoh, Takashi Saeki. On pipe diameter effects in surfactant drag-reducing pipe flows[J]. Rheol Acta,1998, 37(2):122-128.
[10]罗彬文.表面活性剂对突扩和突缩流局部阻力特性的改变研究[D].湖南:湖南工业大学,2016.