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Dynamics of bubble collapse near an armored free surface 装甲自由表面附近的气泡坍塌动力学
IF 3.2 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2024-04-25 DOI: 10.1016/j.expthermflusci.2024.111225
Xujun Fan , Fangye Lin , Jihua Zou , Jun Zou

Armored surfaces refer to a liquid–air interface covered by a layer of floating particles. This paper examines the collapse dynamics of a bubble generated by an electric spark near such an armored surface. The collapse of the bubble near the armored surface is similar to that near a free surface, with the formation of spraying liquid film, upward liquid jet in the forms of water dome, water spike, and water skirt with the change of the vertical distance (l) from the bubble center to the liquid surface. However, on the armored surface, we also observe particle splash and solid–liquid mixture splash. We confirm that the particle splash occurs due to the transfer of shock wave energy during bubble expansion and collapse. The splashing velocity (vp) and the distance (d0) from the bubble center to the particle follow the scaling law of vp ∼ l/d02. Additionally, we discuss the motion of the upward liquid jet and downward vortex ring. We find that the armored surface only affects the initial velocity of the jet without affecting its acceleration. This can be attributed to the additional energy dissipation caused by the splash formed on the armored surface. In contrast, the trajectory of the vortex ring remains unaffected by the armored surface. This study provides valuable insights into the dynamics of bubble collapse near an armored surface and highlights the role of floating particles in altering the behavior of liquid jets.

铠装表面指的是被一层漂浮颗粒覆盖的液气界面。本文研究了电火花在这种铠装表面附近产生的气泡的坍塌动力学。气泡在铠装表面附近的坍塌过程与自由表面类似,随着气泡中心到液面垂直距离(l)的变化,会形成喷射液膜、水球、水钉和水裙等形式的向上液体射流。然而,在铠装表面,我们还观察到了颗粒飞溅和固液混合物飞溅。我们证实,颗粒飞溅是由于气泡膨胀和坍塌过程中冲击波能量的传递造成的。从气泡中心到粒子的飞溅速度(vp)和距离(d0)遵循 vp ∼ l/d02 的缩放规律。此外,我们还讨论了向上的液体射流和向下的涡环运动。我们发现,铠装表面只影响射流的初速度,而不影响其加速度。这可能是由于在装甲表面形成的飞溅造成了额外的能量耗散。相比之下,涡旋环的轨迹不受装甲表面的影响。这项研究为了解装甲表面附近气泡坍塌的动力学提供了宝贵的见解,并突出了漂浮粒子在改变液体射流行为方面的作用。
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引用次数: 0
Characterizing boiling behaviors in water/ethanol binary droplet impact on a heated plate 表征水/乙醇二元液滴撞击加热板时的沸腾行为
IF 3.2 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2024-04-24 DOI: 10.1016/j.expthermflusci.2024.111224
Xiaoyuan Yang , Bingyao Huang , Yi Zhang , Tianyou Lian , Lang Luo , Yuyang Li

This work experimentally investigates the transition boiling behaviors of water/ethanol binary droplets impact on a heated smooth aluminum alloy plate with a high-speed imaging system, forming a more finely defined impact behavior regime map. The dynamic Leidenfrost point temperature exhibits a non-monotonic variation trend with ethanol fraction. Binary droplets exhibit two characteristic boiling behaviors at specific temperatures (Ts) and droplet compositions (Φe), including corona boiling and prompt boiling, distinguished by the elevation of a crown-shaped thick liquid lamella and the prompt generation of numerous secondary droplets from the contact line, respectively. Both boiling behaviors are featured with the violent breakup of parent droplet into about 10 or more fragment droplets (secondary droplets with D ≥ 0.3 mm) and the short residence times on the wall, while exhibiting different splash angle distributions of satellite droplets (secondary droplets with D < 0.3 mm). Characteristic parameter analysis of the two boiling behaviors is conducted to provide qualitative mechanistic explanations. Corona boiling occurs at Φe = 25% & 50% with a lower temperature range (Ts ≤ 200 ℃), the liftoff of the liquid layer is attributed to the combined effect of decelerated wetting speed caused by evaporation and the vapor-induced lift. Prompt boiling occurs at Φe = 25% & 50% with Ts ≥ 220 °C and Φe = 75% with Ts < 200 °C, the intensity of the bubble cloud determines whether the central part of the droplet forms a jet or a liquid bulk filled with microbubbles. This work will provide some new insights into the boiling behaviors and the regulation of secondary atomization of binary solution droplets impact studies.

本研究利用高速成像系统对水/乙醇二元液滴撞击加热的光滑铝合金板的过渡沸腾行为进行了实验研究,形成了更精细的撞击行为体系图。动态莱顿弗罗斯特点温度与乙醇分数呈非单调变化趋势。二元液滴在特定温度(Ts)和液滴成分(Φe)下表现出两种特征性沸腾行为,包括电晕沸腾和迅速沸腾,分别表现为冠状厚液层的升高和从接触线迅速产生大量次级液滴。这两种沸腾行为的特点都是母液滴剧烈破裂成约 10 个或更多的碎片液滴(D ≥ 0.3 mm 的次级液滴),在液滴壁上的停留时间很短,而卫星液滴(D < 0.3 mm 的次级液滴)则表现出不同的飞溅角分布。我们对这两种沸腾行为进行了特征参数分析,以提供定性的机理解释。电晕沸腾发生在 Φe = 25% & 50% 的较低温度范围内(Ts ≤ 200 ℃),液层的升力归因于蒸发引起的湿润速度减慢和蒸汽引起的升力的共同作用。气泡云的强度决定了液滴的中心部分是形成射流还是形成充满微气泡的液块。这项工作将为二元溶液液滴的沸腾行为和二次雾化调节影响研究提供一些新的见解。
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引用次数: 0
Experimental investigations on the effects of longitudinal groove fabric for drag reductions on a track cyclist 纵向沟槽织物对轨道自行车运动员减少阻力效果的实验研究
IF 3.2 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2024-04-21 DOI: 10.1016/j.expthermflusci.2024.111223
Chuntai Zheng, Peng Zhou, Jiaqi Mao, Xin Zhang

The previous study has shown that the longitudinal groove fabric can reduce drag forces on a circular cylinder by forcing a drag crisis (Zheng et al. 2021). In this study, the effects of the longitudinal groove fabric are investigated on a full-scale track cycling mannequin. The force measurement results show that the longitudinal groove fabric on the upper arms can achieve a maximum drag reduction of about 7% at a flow speed of 17 m/s, and its control effects depend on flow speeds. Large-scale particle image velocimetry measurements further show that the drag reductions on the upper arm are characterized by diminished streamwise velocity deficits. The control effects also vary on different spanwise locations of the arm, where the flow behaves distinctively. The measurements also reveal the distinct flow dynamics at different heights, i.e., wake interactions and swirling motions, showing the complexity of reducing drag forces from a track cyclist.

之前的研究表明,纵向沟槽织物可以通过强迫阻力危机来减少圆柱体上的阻力(Zheng 等人,2021 年)。在本研究中,纵向沟槽织物在全尺寸场地自行车人体模型上的效果进行了研究。测力结果表明,在流速为 17 米/秒时,上臂的纵向沟槽织物可实现最大约 7% 的阻力减小,其控制效果取决于流速。大尺度粒子图像测速测量进一步表明,上臂阻力减少的特点是流向速度缺陷减小。控制效果还因上旋臂的不同跨度位置而异,这些位置的气流表现各不相同。测量结果还显示了不同高度上的不同流动动态,即尾流相互作用和漩涡运动,显示了减少赛道自行车阻力的复杂性。
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引用次数: 0
Dynamic characterization of Fiber Bragg Grating temperature sensors 光纤布拉格光栅温度传感器的动态特性分析
IF 3.2 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2024-04-18 DOI: 10.1016/j.expthermflusci.2024.111222
Clemens Naumann , Tommaso Carlesi , Henning Otto , Christian Cierpka , Delphine Laboureur

To reliably characterize fast dynamic heat transfer mechanisms, fast-response temperature sensors are crucial, including knowledge about the temporal response. In this paper, the dynamic behavior of a Fiber Bragg Grating temperature sensor is investigated and compared to different types of fast-response thermocouples using two different experimental dynamic characterization methods. A temperature step is generated by either plunging the sensor into a fluid or exposing it to a fluid droplet at different temperatures. The step response is evaluated to determine the sensor response time. Calibration runs are performed for a silica-based 0.125 mm FBG sensor, as well as for 0.16 mm and 0.8 mm exposed tip and 0.25 mm sheathed tip type K thermocouples. Water, glycerin, oil and GaInSn were used to cover a broad range of applications regarding different thermal diffusivities and viscosities. The FBG sensor showed the shortest response times compared to the thermocouples, ranging from 60 ms in oil down to 3 ms in liquid metal, which is 20 % up to 70 % faster compared to a 0.25 mm sheathed tip type K thermocouple. Additional plunging calibration runs of the FBG sensor were performed in a ternary nitrate molten salt mixture (HITEC) to determine its overall and dynamic behavior in corrosive fluids at elevated temperatures. It turns out that the FBG sensor is not affected by the molten salt and shows similar response times to those measured in water. Regarding the characterization methods, both techniques show reproducible results, even though the droplet method is inapplicable for sensors with higher heat capacity or lower thermal conductivity than the calibration fluid. Furthermore, splashing effects for fluids with low viscosity reduce the reliability of the droplet method. The results also show that a dynamic characterization is indispensable for temperature measurements with high temporal resolution because the response time depends on the sensor size and the heat transfer coefficient between sensor and surrounding, which in turn depends on the sensor type, fluid properties and the flow parameters.

要可靠地表征快速动态传热机制,快速响应温度传感器(包括时间响应知识)至关重要。本文采用两种不同的实验动态表征方法,对光纤布拉格光栅温度传感器的动态行为进行了研究,并与不同类型的快速响应热电偶进行了比较。将传感器插入流体中或暴露在不同温度的流体液滴中会产生温度阶跃。对阶跃响应进行评估,以确定传感器的响应时间。对基于二氧化硅的 0.125 毫米 FBG 传感器以及 0.16 毫米和 0.8 毫米裸露顶端和 0.25 毫米护套顶端 K 型热电偶进行了校准运行。水、甘油、油和 GaInSn 被广泛应用于不同的热扩散率和粘度。与热电偶相比,FBG 传感器的响应时间最短,在油中为 60 毫秒,在液态金属中为 3 毫秒,与 0.25 毫米带护套的 K 型热电偶相比,响应时间快 20% 至 70%。在三元硝酸盐熔盐混合物(HITEC)中对 FBG 传感器进行了额外的柱塞校准运行,以确定其在高温腐蚀性流体中的整体和动态行为。结果表明,FBG 传感器不受熔盐的影响,其响应时间与在水中测量的响应时间相似。在表征方法方面,尽管液滴法不适用于热容量比校准流体高或热导率比校准流体低的传感器,但两种技术都显示出了可重复的结果。此外,低粘度液体的飞溅效应也降低了液滴法的可靠性。结果还表明,动态特性分析对于高时间分辨率的温度测量是必不可少的,因为响应时间取决于传感器的尺寸以及传感器与周围环境之间的传热系数,而传热系数又取决于传感器类型、流体特性和流动参数。
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引用次数: 0
Investigation of fluid flow during flow boiling inside a horizontal rectangular channel with single-sided heating using particle image velocimetry 利用粒子图像测速仪研究单面加热的水平矩形通道内流动沸腾时的流体流动情况
IF 3.2 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2024-04-17 DOI: 10.1016/j.expthermflusci.2024.111221
Chinmay Shingote, Farshad Barghi Golezani, Chirag R. Kharangate

Subcooled flow boiling is a highly efficient cooling systems for thermal management systems. This study explores the intricate dynamics of subcooled flow boiling within a horizontal channel, investigating the impact of vapor generation on liquid-phase velocity using Particle Image Velocimetry (PIV) and advanced image processing techniques. Four mass flow rates ranging from 5–20 g/s with subcooled inlet conditions are investigated in a rectangular channel with single-sided heating. Three regions of interest along the heated channel are investigated for instantaneous PIV analysis. The PIV system captures detailed velocity profiles, illustrating the impact of varying mass flow rates and heat flux levels on flow behavior. Vapor masking techniques are introduced to enhance the precision of PIV data by mitigating interference from the vapor phase. Results demonstrate the influence of vapor bubbles on flow resistance, revealing non-uniform velocity distributions and turbulence near the liquid–vapor interface. The study emphasizes the critical role of inertia and buoyancy forces in shaping the velocity profiles. Moreover, the investigation sheds light on the effects of flow rates on the interfacial behaviors, hinting at a transition point between 10 and 15 g/s. In summary, this research contributes valuable insights into the nuanced dynamics of flow boiling, laying the foundation for future studies on turbulence, heat transfer, and phase-change phenomena in two-phase thermal management systems.

过冷流沸腾是热管理系统的一种高效冷却系统。本研究利用粒子图像测速仪(PIV)和先进的图像处理技术,探讨了水平通道内过冷流沸腾的复杂动态,研究了蒸汽产生对液相速度的影响。在单侧加热的矩形通道中,研究了过冷入口条件下 5-20 克/秒的四种质量流量。沿加热通道对三个感兴趣的区域进行了研究,以进行瞬时 PIV 分析。PIV 系统捕捉到了详细的速度剖面图,说明了不同质量流量和热通量水平对流动行为的影响。引入了气相掩蔽技术,通过减轻气相干扰来提高 PIV 数据的精度。结果表明了气泡对流动阻力的影响,揭示了液体-蒸汽界面附近不均匀的速度分布和湍流。研究强调了惯性力和浮力在形成速度曲线中的关键作用。此外,研究还揭示了流速对界面行为的影响,暗示了 10 至 15 克/秒之间的过渡点。总之,这项研究为了解流动沸腾的微妙动态提供了宝贵的见解,为今后研究两相热管理系统中的湍流、传热和相变现象奠定了基础。
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引用次数: 0
Improved estimation of yaw angle and surface pressure distribution of Ahmed model with optimized sparse sensors by Bayesian framework based on pressure-sensitive paint data 基于压敏涂料数据的贝叶斯框架改进了带有优化稀疏传感器的 Ahmed 模型的偏航角和表面压力分布估计值
IF 3.2 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2024-04-16 DOI: 10.1016/j.expthermflusci.2024.111210
Ryoma Inoba, Kazuki Uchida, Yuto Iwasaki, Keigo Yamada, Ayoub Jebli, Takayuki Nagata, Yuta Ozawa, Taku Nonomura

The present study provides a Bayesian framework for the estimation of the yaw angle and the pressure distribution on the surface of the vehicle from the spatially sparse pressure measurements obtained by optimized sensing locations and data-driven models. The framework is demonstrated on the Ahmed model which is the simplified car model. The yaw angle and the pressure distribution on the top surface of the Ahmed model are estimated based on the sparse pressure measurement on the top surface. The estimation models are constructed based on the time-averaged pressure distribution on the top surface of the car model with various yaw angles obtained by a pressure-sensitive paint technique. The estimation model for the yaw angle was constructed as the linear regression between the yaw angle and pressure at the sensing locations, and the estimation model for the pressure distribution was constructed from a POD-based reduced order model. The Bayesian estimation was newly adopted for the mode coefficient estimation of the reduced-order model of the pressure distribution, and the optimization method of the sensing locations for the Bayesian estimation was adopted. The performance of the present Bayesian method was compared with previously proposed methods, and the results showed that the Bayesian method provides the best performance under most conditions on the yaw angle estimation and the pressure distribution reconstruction. In addition, various combinations of the estimation method and sensing location optimization method were tested, and the impact of estimation and sensing locations was discussed.

本研究提供了一个贝叶斯框架,用于从通过优化传感位置和数据驱动模型获得的空间稀疏压力测量值中估计偏航角和车辆表面的压力分布。该框架在简化汽车模型 Ahmed 模型上进行了演示。根据对 Ahmed 模型顶表面的稀疏压力测量结果,估算出模型的偏航角和顶表面的压力分布。估算模型是根据压敏涂料技术获得的不同偏航角下汽车模型上表面的时间平均压力分布构建的。偏航角的估计模型由偏航角与传感位置压力之间的线性回归建立,压力分布的估计模型由基于 POD 的降阶模型建立。压力分布的降阶模型的模态系数估计采用了新的贝叶斯估计方法,并采用了贝叶斯估计的传感位置优化方法。将本贝叶斯方法的性能与之前提出的方法进行了比较,结果表明,在大多数条件下,贝叶斯方法在偏航角估计和压力分布重建方面的性能最佳。此外,还测试了估计方法和传感位置优化方法的各种组合,并讨论了估计和传感位置的影响。
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引用次数: 0
Development of compact-modulated absorption/emission technique towards micro-gravity sooting flame measurements 开发用于微重力烟尘火焰测量的紧凑型调制吸收/发射技术
IF 3.2 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2024-04-12 DOI: 10.1016/j.expthermflusci.2024.111212
Qianlong Wang , Zhen Li , Xiaoqing You , Haifeng Liu , Mingfa Yao , Yi Wu

To meet the experimental physical limitations on Chinese Space Station (CSS), three compact-modulated absorption/emission (CMAE) implementations are miniaturized progressively from original MAE layout, which are investigated as potential options for simultaneous soot temperature and volume fraction measurements in the axis-symmetric flames. Contrasted with the original MAE technique, a white LED point light source (diameter of ϕ = 8 mm) and a white LED planar light source (rectangle of 200 × 120 mm2) in turns replaces the laser source, by which the light beam homogeneous implementation is significantly simplified. Moreover, a 3-CMOS prism-based camera enables simultaneously recording flame two color radiations that reduces the detecting complexity. It is found that backlight beam intensity should be more than 2.5 times the flame radiation intensity to avoid abnormal extinction coefficient on the flame edge in this configuration. Moreover, the robustness and consistency of the three CMAEs measurements are validated with a standard Santoro’s flame, and low average standard deviation ranges of ±0.04 ±0.06 ppm and ±65.0 ± 96.3 K for soot volume fraction and temperature respectively is evaluated from error propagation assessment. As such, the proposed CMAE-2 and CMAE-3 layouts are promising candidates for high-fidelity flame soot parameters measurements under limited space, weight and power supply on CSS.

为了满足中国空间站(CSS)上的实验物理限制,在原始 MAE 布局的基础上逐步实现了三种紧凑型调制吸收/发射(CMAE)装置的小型化,并将其作为轴对称火焰中同时测量烟尘温度和体积分数的潜在方案进行了研究。与原始 MAE 技术相比,白光 LED 点光源(直径 ϕ = 8 毫米)和白光 LED 平面光源(200 × 120 平方毫米的矩形)轮流取代了激光光源,从而大大简化了光束均匀性的实现。此外,基于 3-CMOS 棱镜的摄像头可同时记录两种颜色的火焰辐射,从而降低了检测的复杂性。研究发现,背光光束强度应大于火焰辐射强度的 2.5 倍,以避免在这种配置下火焰边缘出现异常消光系数。此外,用标准桑托罗火焰验证了三种 CMAE 测量方法的稳健性和一致性,并通过误差传播评估得出烟尘体积分数和温度的平均标准偏差范围分别为 ±0.04 ∼ ±0.06 ppm 和 ±65.0 ∼ ± 96.3 K。因此,拟议的 CMAE-2 和 CMAE-3 布局有望在 CSS 上有限的空间、重量和电源条件下实现高保真火焰烟尘参数测量。
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引用次数: 0
Experimental study on the influence of inlet pressure on the flow parameters at the reverse flow boundary of vortex tube and its relation with energy separation performance 入口压力对涡管反向流边界流动参数的影响及其与能量分离性能关系的实验研究
IF 3.2 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2024-04-12 DOI: 10.1016/j.expthermflusci.2024.111211
Chen Guangming , Jiang Guannan , Tang Liming , Li Nian

The performance of the vortex tube (also known as the Ranque-Hilsch tube) is significantly influenced by the inlet pressure and the internal flow processes, which can be categorized into two distinct flows: the center and the outer flow. The reverse flow boundary, acting as the interface between the two flows, plays a crucial role in energy separation. However, the research on the location of the reverse flow boundary and the associated flow parameters and energy transfer at this boundary are still insufficient. Therefore, this research employs the measurement method of interpolation probe to analyze the distribution of the reverse flow boundary and the specific flow parameters at this boundary. These parameters include static pressure gradient, angular velocity, and static temperature gradient, which substantially impact energy separation. A qualitative analysis of the energy transfer process in the vortex tube by examining mass flow in the reverse area and tangential and axial velocities are further delved. This analysis covers momentum transfer, heat transfer, and turbulent heat transfer processes resulting from the compression and expansion processes. The findings provide a research direction for exploring the energy separation performance of vortex tubes.

涡流管(又称兰克-希尔施管)的性能受入口压力和内部流动过程的影响很大,内部流动过程可分为两种不同的流动:中心流和外侧流。反向流动边界作为两股流动的界面,在能量分离中起着至关重要的作用。然而,对反向流边界的位置、相关的流动参数以及该边界的能量传递的研究仍然不足。因此,本研究采用插值探针的测量方法来分析反向流边界的分布以及该边界的具体流动参数。这些参数包括静压梯度、角速度和静态温度梯度,它们对能量分离有重大影响。通过研究反向区域的质量流以及切向和轴向速度,进一步深入研究了涡流管中能量传递过程的定性分析。该分析涵盖了压缩和膨胀过程产生的动量传递、热量传递和湍流热量传递过程。研究结果为探索涡流管的能量分离性能提供了一个研究方向。
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引用次数: 0
Study of the flow pattern and pressure drop law of the air-water-foam three-phase flow 空气-水-泡沫三相流的流动模式和压降规律研究
IF 3.2 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2024-04-07 DOI: 10.1016/j.expthermflusci.2024.111207
Guowei Wang , Ruiquan Liao , Lijuan Huang , Qi Xia , Manlai Zhang , Yu Lei , Wei Wang

The inaccurate prediction of flow patterns and pressures after adding different types and concentrations of surfactants to wellbores and drainage lines is a common problem in shale gas wells and tubing foam drainage. To clarify the change rule of the air–water-foam three-phase flow pattern and pressure drop after adding different types and concentrations of surfactants, a surface tension test was conducted in this study. In addition, visual air–water-foam three-phase flow indoor simulation experiments were performed with various surfactants such as cocamidopropyl hydroxysulfobetaine (MX-1), dodecyldimethyl betaine (TCJ-1), and sodium α-alkenyl sulfonate (XJHSM), surfactant concentrations (0.3–0.6 %), oil pipe diameters, pipe inclinations, gas–liquid ratios, and oil contents on large-scale experimental equipment. Based on the gas–liquid distribution characteristics, the air–water-foam three-phase flow patterns in the inclined tube were reclassified, and the quantitative conversion boundaries of the various flow patterns were determined. Based on the pressure drop pulse characteristics, characterization parameters such as the scaling factor, foaming capacity, foam density, and gas-holding rate were introduced after considering the effects of various factors on the pressure drop weights, enabling a new pressure drop calculation method for air–water-foam three-phase flows for application to different types and concentrations of surfactants. The errors were verified using data from previous studies and field measurements that were within 15% and 5%, respectively. The results of these studies provide a better understanding of the air–water-foam three-phase flow patterns and pressure drop variations in shale gas wells and gathering lines.

在井筒和排液管线中加入不同类型和浓度的表面活性剂后,对流动模式和压力的预测不准确是页岩气井和油管泡沫排液中的一个常见问题。为了明确加入不同类型和浓度的表面活性剂后气-水-泡沫三相流型和压降的变化规律,本研究进行了表面张力试验。此外,还在大型实验设备上对椰油酰胺丙基羟基磺基甜菜碱(MX-1)、十二烷基二甲基甜菜碱(TCJ-1)、α-烯基磺酸钠(XJHSM)等不同表面活性剂、表面活性剂浓度(0.3%-0.6%)、油管直径、油管倾斜度、气液比、含油量等进行了直观的气-水-沫三相流室内模拟实验。根据气液分布特征,对倾斜管中的气-水-沫三相流动模式进行了重新分类,并确定了各种流动模式的定量转换边界。在压降脉冲特征的基础上,考虑了各种因素对压降权重的影响,引入了缩放因子、发泡能力、泡沫密度和持气率等表征参数,从而得到了一种新的气-水-沫三相流压降计算方法,适用于不同类型和浓度的表面活性剂。利用以前的研究数据和现场测量数据对误差进行了验证,误差分别在 15%和 5%以内。这些研究结果有助于更好地理解页岩气井和集输管线中空气-水-泡沫三相流的流动模式和压降变化。
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引用次数: 0
Experimental studies on simultaneously reducing flow drag and noise of a circular cylinder with a downstream porous material plate 同时降低带有下游多孔材料板的圆筒的流动阻力和噪音的实验研究
IF 3.2 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2024-04-06 DOI: 10.1016/j.expthermflusci.2024.111209
Chen Xu , Xiaojiang Gu , Yijun Mao , Chao Wang

Pressure drag and noise level are two key parameters related to flow past a bluff body, thus various active and passive methods have been developed to reduce the drag and noise. The paper presents a passive method of simultaneously reducing the pressure drag and aerodynamic noise associated with flow past a smooth circular cylinder by placing a porous material plate (PMP) downstream the cylinder. Multi-points instantaneous wall pressure and far-field acoustic pressure have been measured in an anechoic wind-tunnel facility. The experimental results confirm that the PMP is effective to reduce both the pressure drag and the noise level, showing an attractive advantage compared with the impermeable splitter plate and porous coating. Parametric studies reveal effects of the pores per inch (PPI) of PMP, PMP-cylinder spacing and incoming flow velocity on the pressure drag and noise level.

压力阻力和噪音水平是与流经崖体有关的两个关键参数,因此人们开发了各种主动和被动方法来减少阻力和噪音。本文提出了一种被动方法,通过在光滑圆筒下游放置多孔材料板(PMP),同时降低流经圆筒时产生的压力阻力和空气动力噪声。在消声风洞设施中测量了多点瞬时壁压和远场声压。实验结果证实,PMP 能有效降低压力阻力和噪音水平,与不透水的分流板和多孔涂层相比,显示出极具吸引力的优势。参数研究揭示了 PMP 的每英寸孔隙 (PPI)、PMP-圆筒间距和入流速度对压力阻力和噪音水平的影响。
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Experimental Thermal and Fluid Science
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