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Dynamics of Bubbles in a Spherical Cluster under Increasing Liquid Pressure 液体压力增大时球形簇中气泡的动态变化
IF 1 4区 物理与天体物理 Q3 Engineering Pub Date : 2024-03-21 DOI: 10.1134/s0018151x23050103
R. I. Nigmatulin, A. A. Aganin, I. A. Aganin, A. I. Davletshin

Abstract

The response of gas (air) bubbles in a spherical cluster to an increase in the pressure of the surrounding liquid (water) is considered. Consideration is carried out only until a bubble in the cluster disintegrates or collides with another bubble. The influence of the amplitude of the increase in the liquid pressure, as well as the position of the bubbles in the cluster and the interaction between the bubbles, is studied. The centers of the cluster bubbles are located at the nodes of a cubic grid, one of which is in the center of the cluster. The effect of the interaction of bubbles is assessed by comparison with the response of a single bubble. The cluster consists of 123 bubbles, the liquid pressure is 1 bar. Initially, the bubbles are spherical with a radius of 0.1 mm, the cluster radius is about 3 mm. A discrete model is used, in which, together with the radial oscilations of bubbles, their movements in the liquid and their small deformations are also modeled. It is established that the maximum pressure in the bubbles, reached before the destruction or collision of any of them, is realized when the liquid pressure increases by 10 bar and turns out to be approximately 6500 times greater than their initial pressure and approximately 30 times greater than the response of a single bubble.

摘要 研究了球形气泡团中的气体(空气)对周围液体(水)压力增加的反应。只考虑到气泡团中的一个气泡解体或与另一个气泡碰撞。研究了液体压力增加的幅度、气泡在气泡团中的位置以及气泡之间相互作用的影响。气泡群的中心位于立方网格的节点上,其中一个节点位于气泡群的中心。通过与单个气泡的响应进行比较,评估了气泡相互作用的影响。气泡群由 123 个气泡组成,液体压力为 1 巴。最初,气泡为半径为 0.1 毫米的球形,气泡簇半径约为 3 毫米。使用的是离散模型,其中除了气泡的径向振荡外,还模拟了气泡在液体中的运动和微小变形。结果表明,当液体压力增加 10 巴时,气泡中的最大压力会在任何一个气泡被破坏或碰撞之前达到,比气泡的初始压力高出约 6500 倍,比单个气泡的反应高出约 30 倍。
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引用次数: 0
Heat Transfer Enhancement and Interaction of Rivulets on the Surface of a Heated Liquid Film 加热液体薄膜表面的热传导增强和细流的相互作用
IF 1 4区 物理与天体物理 Q3 Engineering Pub Date : 2024-03-20 DOI: 10.1134/s0018151x2303015x
E. A. Chinnov

Abstract

The flow of an aqueous film along a vertical heater was studied for Reynolds numbers of 33, 50, and 105 and initial temperatures T0 = 15, 23, 30, and 40°С. It was shown that the amplitudes of the zigzag motion of the rivulets increased with increasing heat flux density. The most intensive growth of amplitudes was observed with the development of thermocapillary instability in the upper part of the heater. For high heat fluxes, when the amplitude of the zigzag motion reached a sufficiently large value, interaction of the rivulets began. Several types of interaction of rivulets on the surface of the heated liquid film were distinguished. It was shown that the appearance of a thermocapillary structure in the upper part of the heater led to movement of rivulets and an increase in the heat transfer intensity.

摘要 在雷诺数为 33、50 和 105 以及初始温度 T0 = 15、23、30 和 40°С 时,研究了水膜沿垂直加热器的流动。结果表明,随着热通量密度的增加,涡流的 "之 "字形运动幅度也随之增大。在加热器上部出现热毛细管不稳定性时,振幅增长最为明显。在热通量较高的情况下,当之字形运动的振幅达到足够大的值时,涡流开始相互作用。受热液膜表面上的微流相互作用分为几种类型。研究表明,加热器上部热毛细管结构的出现导致了微流的运动和传热强度的增加。
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引用次数: 0
Estimation of Convective Heat Fluxes for Meteoroid Bodies in a Three-Dimensional Formulation 流星体对流热通量的三维估算公式
IF 1 4区 物理与天体物理 Q3 Engineering Pub Date : 2024-03-20 DOI: 10.1134/s0018151x23040090
D. N. Minyushkin, I. S. Frolov

Abstract

This paper proposes a modified effective length method for calculating heat fluxes in complex geometries in a three-dimensional formulation when moving in the atmosphere at high speeds and describes its software implementation. The method, on the one hand, does not require huge computational costs to obtain results, and on the other, demonstrates stable operation in complex geometries.

摘要 本文提出了一种修正的有效长度方法,用于计算复杂几何体在大气中高速运动时的三维热通量,并介绍了该方法的软件实现。该方法一方面不需要巨大的计算成本就能获得结果,另一方面在复杂几何体中运行稳定。
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引用次数: 0
Influence of Laser Microdisection of the Zona Pellucida of Embryos on the Its Thinning Dynamics under Cryopreservation Protocols 胚胎透明带激光显微切割对冷冻保存方案下胚胎透明带变薄动态的影响
IF 1 4区 物理与天体物理 Q3 Engineering Pub Date : 2024-03-20 DOI: 10.1134/s0018151x23040144
D. S. Sitnikov, D. E. Mukhdina, D. S. Korshunova, Yu. Yu. Silaeva, M. A. Filatov, I. V. Ilina

Abstract

The authors studied the dynamics of thinning of the zona pellucida (ZP) in mouse embryo as a result of laser-assisted hatching performed at the blastocyst stage. Mouse embryos previously subjected to a freeze–thaw cycle (cryo-embryos) were selected as model embryos. For ZP microsurgery, femtosecond laser pulses were used (radiation wavelength 512 nm, pulse duration 100 fs, intensity 2.5 TW/cm2). The thickness of the ZP was measured before microsurgery at the blastocyst stage (~E3.5, i.e., 3.5 days of embryonic development) and at the hatching stage (~E5). It was found that the ZP of control group embryos (cryo-embryos not subjected to laser exposure) thinned more strongly (from 6.6 (E3.5) to 4.9 µm (E5)) compared to experimental embryos after the laser-assisted hatching procedure (from 7.1 ( E3.5) to 6.4 µm (E5)). In both the first and second cases, changes in ZP thickness were statistically significant. The results were compared with data for “fresh” embryos not subjected to cryopreservation. There was no pronounced effect of ZP hardening in cryo-embryos compared to fresh embryos. The use of the laser-assisted hatching procedure for cryo-embryos made it possible to increase the probability of successful hatching compared to embryos in the control group from 38.5 to 52.5%.

摘要 作者研究了在囊胚期进行激光辅助孵化导致小鼠胚胎透明带变薄的动态变化。小鼠胚胎先前经过冻融循环(冷冻胚胎),被选为模型胚胎。ZP 显微手术使用飞秒激光脉冲(辐射波长 512 nm,脉冲持续时间 100 fs,强度 2.5 TW/cm2)。在囊胚期(~E3.5,即胚胎发育的 3.5 天)和孵化期(~E5)进行显微手术前测量了 ZP 的厚度。结果发现,对照组胚胎(未接受激光照射的冷冻胚胎)的 ZP 变薄(从 6.6(E3.5)微米到 4.9 微米(E5)),而实验组胚胎在接受激光辅助孵化程序后的 ZP 变薄(从 7.1(E3.5)微米到 6.4 微米(E5))。在第一种和第二种情况下,ZP 厚度的变化都具有显著的统计学意义。这些结果与未进行冷冻保存的 "新鲜 "胚胎的数据进行了比较。与新鲜胚胎相比,冷冻胚胎的 ZP 硬化效果并不明显。与对照组胚胎相比,冷冻胚胎使用激光辅助孵化程序可将成功孵化的概率从 38.5%提高到 52.5%。
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引用次数: 0
Experimental Study of the Heat Transfer at Compressible Gas Flow with a Favorable Pressure Gradient 有利压力梯度的可压缩气体流动传热实验研究
IF 1 4区 物理与天体物理 Q3 Engineering Pub Date : 2024-03-20 DOI: 10.1134/s0018151x23040065
N. A. Kiselev, N. S. Malastovskii, A. G. Zditovets, Yu. A. Vinogradov

Abstract

The parameters of heat transfer at compressible gas flow with a favorable pressure gradient have been experimentally studied. The heat transfer coefficients and the temperature of thermally insulated (adiabatic) wall are determined using the transient heat transfer method. To estimate the degree of flow laminarization, the results obtained are compared with the known dependences for the turbulent boundary layer developing on a plate in a zero-pressure gradient flow. Some regularities of the effect of flow acceleration on the heat transfer law are revealed for the studied configurations of supersonic nozzles.

摘要 对具有有利压力梯度的可压缩气体流动的传热参数进行了实验研究。采用瞬态传热方法确定了热传导系数和隔热(绝热)壁的温度。为了估计流动层流化的程度,将所获得的结果与已知的零压力梯度流动中板上形成的湍流边界层的相关系数进行了比较。针对所研究的超音速喷嘴配置,揭示了流动加速度对传热规律影响的一些规律性。
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引用次数: 0
Boiling Modes of Helium II on a Cylindrical Heater Inside a Porous Structure 多孔结构内圆柱形加热器上氦气 II 的沸腾模式
IF 1 4区 物理与天体物理 Q3 Engineering Pub Date : 2024-03-20 DOI: 10.1134/s0018151x23030185
Yu. Yu. Puzina, A. P. Kryukov

Abstract

Experimental data on the study of boiling of superfluid helium (helium II) on a cylindrical heater inside a porous structure are considered. Based on an analysis of video recordings, the heat and mass transfer modes characterized by significant modification of the shape of the phase interface are classified. The values of heat fluxes and heater temperatures are presented, and the degree of nonequilibrium of the corresponding transfer processes is assessed.

摘要 考察了在多孔结构内的圆柱形加热器上研究超流体氦(氦Ⅱ)沸腾的实验数据。根据对视频记录的分析,对以相界面形状的显著改变为特征的传热和传质模式进行了分类。文中给出了热通量和加热器温度值,并评估了相应传质过程的非平衡程度。
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引用次数: 0
Explosive Boiling-up of Superheated Gas-Saturated Alkanes 过热气体饱和烷烃的爆炸性沸腾
IF 1 4区 物理与天体物理 Q3 Engineering Pub Date : 2024-03-20 DOI: 10.1134/s0018151x23040028
V. G. Baidakov, A. M. Kaverin, A. S. Pankov

Abstract

The spontaneous boiling-up kinetics of liquid alkanes (methane, ethane, and propane) saturated with one of the following gases: helium, hydrogen, nitrogen, or methane is studied. The solution nucleation rate temperature, baric, and concentration dependences in the interval (104–108) m–3 s–1 are determined using the mean lifetime method. The measurements were carried out at pressures of 1–2 MPa and volatile component concentrations up to 6 mol %. The experimental results are compared with the classical nucleation theory in a macroscopic approximation. In contrast to pure liquid and liquid saturated with helium or hydrogen, the attainable superheating temperatures of solutions containing nitrogen or methane as a dissolved substance exceed their theoretically predicted values. The factors causing this mismatch are discussed.

摘要 研究了液态烷烃(甲烷、乙烷和丙烷)饱和下列气体之一的自发沸腾动力学:氦气、氢气、氮气或甲烷。采用平均寿命法测定了溶液成核率在 (104-108) m-3 s-1 范围内的温度、巴里和浓度相关性。测量是在压力为 1-2 兆帕和挥发性成分浓度高达 6 摩尔%的条件下进行的。实验结果与宏观近似的经典成核理论进行了比较。与纯液体和氦或氢饱和液体相比,含有氮或甲烷溶解物的溶液可达到的过热温度超出了理论预测值。本文讨论了造成这种不匹配的因素。
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引用次数: 0
Modes of a Liquid Film Falling Down a Vertical Cylinder at Different Contact Angles 不同接触角下垂直圆柱体液膜的下落模式
IF 1 4区 物理与天体物理 Q3 Engineering Pub Date : 2024-03-20 DOI: 10.1134/s0018151x23030173
A. Yu. Sakhnov, O. A. Volodin, N. I. Pecherkin, A. N. Pavlenko

Abstract

We present the results of a three-dimensional numerical simulation of the dynamics of a falling film of a mixture of refrigerants, 0.9 mol fraction R21 + R114, considering the liquid flow along the outer lateral surface of a round vertical cylinder for a Reynolds number of 104 and contact angles of 10°, 30°, 50°, 70°, and 90°. The simulation was carried out using the volume of fluid (VOF) method in the OpenFOAM software. The contact angle has a significant effect on the area of the wetted surface due to a change in the modes of liquid falling down the cylinder. The following flow modes are identified: continuous film, stable jet mode, cascade jet mode, and massive jet mode. These modes are similar to the modes of fluid flow on horizontal tubes.

摘要 我们介绍了对制冷剂混合物(0.9 摩尔分数 R21 + R114)的降膜动力学进行三维数值模拟的结果,考虑了液体沿圆形垂直圆柱体外侧表面的流动,雷诺数为 104,接触角为 10°、30°、50°、70° 和 90°。模拟采用 OpenFOAM 软件中的流体体积 (VOF) 法进行。接触角对润湿表面的面积有显著影响,这是因为液体从圆筒中落下的模式发生了变化。确定了以下流动模式:连续薄膜、稳定喷射模式、级联喷射模式和大量喷射模式。这些模式与水平管上的液体流动模式相似。
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引用次数: 0
Influence of the Moment of High Frequency Corona Discharge Initiation on the Combustion Development in a Hybrid Compression Engine 高频电晕放电起始时刻对混合压缩式发动机燃烧发展的影响
IF 1 4区 物理与天体物理 Q3 Engineering Pub Date : 2024-03-12 DOI: 10.1134/s0018151x23030082
E. A. Filimonova, A. S. Dobrovolskaya

Abstract

The work shows the dependence of the moment of the discharge-activated zone ignition and the moment of self-ignition of the fuel mixture in the region ahead of the combustion wave front on two parameters: the crankshaft rotation angle at which the discharge was initiated and the specific energy input into the streamer channel. It is shown the necessity to take into account the change in pressure in the cylinder due to the movement of the piston in order to more accurately determine the optimal ignition limits of the activated zone and the occurrence of self-ignition. When modeling, the inhomogeneous formation of chemically active particles associated with the streamer and multi-pulse nature of the discharge was taken into account.

摘要 该研究表明,放电激活区点火时刻和燃烧波前区域燃料混合物自燃时刻取决于两个参数:放电启动时的曲轴旋转角度和输入流道的比能量。结果表明,有必要考虑活塞运动导致的气缸内压力变化,以便更准确地确定激活区的最佳点火极限和自燃的发生。在建模时,考虑到了与流线和多脉冲放电性质相关的化学活性颗粒的不均匀形成。
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引用次数: 0
Processes Occurring in a Coolant Spray Cone 冷却剂喷锥中发生的过程
IF 1 4区 物理与天体物理 Q3 Engineering Pub Date : 2024-03-12 DOI: 10.1134/s0018151x23020104
A. T. Komov, A. V. Zakharenkov, V. V. Tolmachev, V. S. Shteling

Abstract

The study considers generation of a dispersed coolant flow; the size distribution of droplets in the flow depending on the flow rate, pressure, and thermophysical properties of the coolant; the breakup and coagulation of droplets; and droplet size ranges resistant to breakup. A computer code for calculating the evolution of the spray cone parameters was developed based on the momentum equation and distribution of droplets along the radius in the flow at the atomizer nozzle.

摘要 该研究考虑了分散冷却剂流的产生;冷却剂流中液滴的大小分布(取决于冷却剂的流速、压力和热物理性质);液滴的破裂和凝结;以及不易破裂的液滴大小范围。根据动量方程和雾化器喷嘴处液滴沿流动半径的分布情况,开发了计算喷雾锥参数演变的计算机代码。
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引用次数: 0
期刊
High Temperature
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