共查询到18条相似文献,搜索用时 93 毫秒
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涡流管是一种没有任何运动部件的简单的能量分离装置,它能够将高压气体分离为温度不同冷热两股气流。对涡流管的性能的影响因素很多,例如进气压力,进气口的温度,长径比,冷流率以及涡流管的结构参数等。为了研究不同因素对涡流管性能的影响,以达到提高涡流管的效率的目的。用三维数值模拟的方法和实验相结合,主要研究进气口压力和冷流率的变化对涡流管的性能的影响。结果表明随着进气口压力的增加,涡流管的效率不断增加;同时当冷流率在(0.6~0.7)范围时,此时的冷却效率有最大值。 相似文献
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基于自激振荡脉冲效应的雾化喷嘴出口流道空化特性研究 总被引:3,自引:1,他引:3
喷嘴结构及射流运动参数对液体空化流动状态有重要影响。基于空化泡溃灭的雾化机理和自激振荡脉冲喷嘴出口流道空化过程,分析空化效应对自激振荡脉冲射流雾化效果的影响。依据自激振荡脉冲雾化喷嘴结构,分析射流来流速度和脉动压力对喷嘴出口流道空化效应的影响,提出利用来流雷诺数和脉动特征值表征喷嘴出口流道空化程度,并根据自激振荡脉冲喷嘴有限元分析得到喷嘴出口流道较好空化状态的来流雷诺数和喷嘴腔室长径比。研究结果表明:当来流雷诺数在2.14×10~5~3.05×10~5内逐渐增大时,自激振荡脉冲雾化喷嘴出口流道液相体积分数先减小后增大,相应的空化程度先增大后减小。雷诺数在2.44×10~5~2.75×10~5内可以使喷嘴出口流道形成较好空化效应,尤其在2.44×10~5附近时喷嘴出口流道出现最好的空化状态;脉动特征值与喷嘴出口流道处脉动压力幅值差成正比,随着自激振荡脉冲雾化喷嘴腔室长径比增大,脉动压力幅值差值先减小后增大。当喷嘴腔室长径比为0.60~0.70时,喷嘴出口流道空化状态较好。计算结果为自激振荡脉冲射流雾化喷嘴设计提供了理论依据。 相似文献
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空气涡流制冷及在切削冷却中的应用 总被引:2,自引:0,他引:2
在机械零件的切削加工中,由于种种原因常常不能使用液体进行冷却,而使用压缩空气直接吹冷,又会产生噪声、切屑乱飞等环境公害,而且有时冷却效果也不好,所以这时需要采用其他方法进行切削冷却。笔者研究了空气涡流制冷方法,使用工厂内既有的压缩空气将其接入涡流管,利用涡流产生的“兰克效应”。在冷气出口端产生零下十几度的低温气流用以冷却切削加工区域,而且还可通过调节进气压力、流量来改变冷气流温度和冷气流量,为特殊情况下工作的刀具冷却开辟了~条新的途径。1涡流管冷却作用原理[1]压缩空气由喷嘴以跨声速切向高速射入涡… 相似文献
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为研究收缩喷嘴内部流道形成对射流流场的气体动特性参数的影响,根据可压缩流体轴对称N-S方程,采用非结构网格和二阶精度的有限体积法,对不同内部流道形线的喷嘴自由射流进行数值模拟。亚声速射流采用RNGk-ε湍流模型,超声速射流采用S-A湍流模型,计算结果与实验较吻合。在亚声速流动中,收缩喷嘴的收缩角大小会影响其对射流的阻滞效果,内部流道形线设计为维多辛斯基曲线可以获得更好的流场动特性参数,有利于提高喷嘴的工作效率。在超声速流动中,喷嘴流道型线对出口膨胀波的角度与强弱影响较大,要根据射流的有效作用区域选择合适的喷嘴,才能使能量的损失最小。若要获得较佳的外部流场参数,优化喷嘴内部流道设计十分重要。 相似文献
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收缩喷嘴内部流道型线对射流流场的影响 总被引:4,自引:0,他引:4
为研究收缩喷嘴内部流道形成对射流流场的气体动特性参数的影响,根据可压缩流体轴对称N-S方程,采用非结构网格和二阶精度的有限体积法,对不同内部流道形线的喷嘴自由射流进行数值模拟。亚声速射流采用RNGk-ε湍流模型,超声速射流采用S-A湍流模型,计算结果与实验较吻合。在亚声速流动中,收缩喷嘴的收缩角大小会影响其对射流的阻滞效果,内部流道形线设计为维多辛斯基曲线可以获得更好的流场动特性参数,有利于提高喷嘴的工作效率。在超声速流动中,喷嘴流道型线对出口膨胀波的角度与强弱影响较大,要根据射流的有效作用区域选择合适的喷嘴,才能使能量的损失最小。若要获得较佳的外部流场参数,优化喷嘴内部流道设计十分重要。 相似文献
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Abstract In this study, the effects of the orifice nozzle number and the inlet pressure on the heating and cooling performance of the counter flow type vortex tube is investigated experimentally. The orifices are produced using the polyamide plastic material. Five orifices with 2, 3, 4, 5, and 6 nozzles are manufactured. In this study, air is used as a fluid. In the experiments, for each of the orifices, inlet pressures were adjusted from 150 kPa to 700 kPa with 50 kPa increments and the energy separation was investigated. During the experiments, cold mass fraction of the vortex tube that L/D ratio is 15, is held constant at 0.5. At the end of the experimental study, it is noted that the temperature gradient between the cold and hot fluid is decreased with increasing of the orifice nozzle number. 相似文献
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为了分析多孔射流风机作用下风场的流场特性,文中采用CFD方法,对多孔射流式风场模型内部流场进行了数值模拟,对比分析了不同喷嘴数量及排布方式对流场性能的影响,并引入涡动力学理论,分析了流场内涡结构的分布发展规律及其对流体掺混的影响。结果表明:喷嘴的数量及排布方式对流场性能有显著影响,外围喷嘴会对中心喷嘴的流动起到限制作用;流向涡对流体掺混效果的作用比展向涡大,在涡量一定的情况下,流向涡尺度越大、衰减越快,流体间的混合效果越好,流场稳定性越高。流场内速度及涡动力学分布表明,流场稳定性随着喷嘴数量的增加而显著提高,因此在保证经济性的前提下应尽量采用数量多的喷嘴排布方式。 相似文献
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介绍了基于AT89C52单片机的涡流管控制系统的设计,包括系统硬件和软件的设计。在系统中,对单片机编程实现了四相步进电机的转向及定位控制,再由步进电机驱动涡流管热端阀改变其开度,从而达到控制涡流管冷流率及出口温度的目的。 相似文献
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《Flow Measurement and Instrumentation》1999,10(3):175-181
For calibration of a large capacity gas flow meter, a sonic nozzle bank may be used as a reference system. International standards (ISO9300:1990) allow installation of a single nozzle in a meter tube as a flow transfer standard. For multiple nozzles in a single tube, the effect of interference between sonic nozzles and the chamber wall must be measured to predict the discharge coefficient of a nozzle array from those of single nozzles. The interference effect between neighboring nozzles can be additional error sources in mass flow measurement. Sonic nozzles with three different throat diameters (d=4.3, 8.1, and 13.4 mm) were tested in a single meter tube in three geometrical arrangements. The mass flow rate was measured against a primary gas flow standard system. Three installation plates for sonic nozzles were made to vary the distance between nozzles and distance from the chamber wall. Discharge coefficients of the three individual nozzles were in agreement with the ISO recommended equation within ±0.2%. Discharge coefficients of the nozzle bank calculated from those of the individual sonic nozzle were the same as the direct measurements within ±0.098% at the 95% confidence level for all cases. For these experiments, the results were not influenced by the proximity of the tube wall or the interaction of the nozzles. 相似文献
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Dynamic flow characteristics of a counter-flow vortex tube is investigated using hot-wire and piezoelectric transducer (PZT)
measurements. The experimental study is conducted over a range of cold air outlet ratios (Y=0.3, 0.5, 0.7, and 1.0) and inlet
pressure 0.15 MPa. Temperatures are measured at the cold air outlet and along the vortex tube wall. Hot-wire is located at
cold outlet and PZT is installed at inner vortex tube by mounting at throttle valve. The cold outlet temperature results show
that the swirl flow of vortex tube is not axisymmetric. The hot-wire and PZT results show that there exist two distinct kinds
of frequency, low frequency periodic fluctuations and high frequency periodic fluctuations. It is found that the low frequency
fluctuation is consistent with the Helmholtz frequency and the high frequency fluctuation is strongly related with precession
oscillation. 相似文献
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Chang- Hyun Sohn Chang-Soo Kim Ui-Hyun Jung B. H. L Lakshmana Gowda 《Journal of Mechanical Science and Technology》2006,20(3):418-425
The present investigation deals with the study of the internal flow phenomena of the counter flow type vortex tube using experimental
testing and numerical simulation. Visualization was carried out using the surface tracing method, injecting dye on the vortex
tube wall using a needle. Vortex tube is made of acrylic to visualize the surface particle tracing and the input air pressure
was varied from 0.1 MPa to 0.3 MPa. The experimentally visualized results on the tube show that there is an apparent sudden
changing of the trajectory on the vortex tube wall which was observed in every experimental test case. This may indicate the
stagnation position of the vortex flow. The visualized stagnation position moves towards the vortex generator with increase
in cold flow ratio and input pressure. Three-dimensional computational study is also conducted to obtain more detailed flow
information in the vortex tube. Calculated total pressure, static pressure and total temperature distributions in the vortex
tube were in good agreement with the experimental data. The computational particle trace on the vortex tube wall is very similar
to that observed in experiments. 相似文献