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Investigation on the Flow Instability of Supercritical Hydrocarbon Fuels in Cooling Channels 超临界碳氢燃料在冷却通道中流动不稳定性的研究
IF 2.1 4区 工程技术 Q2 Physics and Astronomy Pub Date : 2023-03-10 DOI: 10.2514/1.t6571
Yichao Jin, Kun Wu, Yang Lu, Xuejun Fan
Flow instability in regenerative cooling channels is an important issue for the thermal protection of hypersonic scramjet engines. Taking into account the dynamic process of the heat transfer and flow instability, a one-dimensional transient model with several modules (including the cracking reaction, convective heat transfer, and rapid calculation of thermal properties) has been developed to investigate the flow instability characteristics of supercritical hydrocarbon fuels in cooling channels. The calculated results were compared and validated against the available experiments and numerical benchmarks, attaining good agreements. By virtue of the transient simulations, the dynamic flow patterns under different flow rates were studied in a single cooling channel with [Formula: see text]-decane being the working substance. Then, the influences of the operating pressure and heated length on the in-tube flow were further investigated. In addition to the Ledinegg instability, several dynamic instability modes were detected under different external driving forces. It was also observed that under a specific range of pressure drop, the in-tube flow could transition from the density-wave oscillation to a new steady state. Moreover, this flow excursion was more likely to be triggered when decreasing the operating pressure or channel length.
再生冷却通道中的流动不稳定性是高超音速超燃冲压发动机热保护的一个重要问题。考虑到传热和流动不稳定的动态过程,建立了一个包含多个模块(包括裂化反应、对流传热和热性能快速计算)的一维瞬态模型,以研究超临界碳氢燃料在冷却通道中的流动不稳定特性。将计算结果与现有的实验和数值基准进行了比较和验证,取得了良好的一致性。通过瞬态模拟,研究了以[公式:见正文]-癸烷为工作物质的单个冷却通道中不同流速下的动态流动模式。然后,进一步研究了操作压力和加热长度对管内流动的影响。除了Ledinegg不稳定外,在不同的外部驱动力下还检测到几种动态不稳定模式。还观察到,在特定的压降范围内,管内流动可以从密度波振荡转变为新的稳态。此外,当降低操作压力或通道长度时,这种流动偏移更有可能被触发。
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引用次数: 0
Upstream Endwall Film-Cooing in a Vane Cascade with Cylindrical Shape Holes 圆柱孔叶片叶栅上游端壁膜曲现象
IF 2.1 4区 工程技术 Q2 Physics and Astronomy Pub Date : 2023-03-09 DOI: 10.2514/1.t6607
B. B. Huyssen, A. S. Shote, G. I. Mahmood
To overcome the disadvantages of cylindrical holes in film cooling, complex geometries of the fan-shaped diffused holes are employed in cascade investigations. The present experiment employs a new design of a diffused hole for film cooling that is formed by diffusing a cylindrical hole smoothly and only in the forward direction. The aerothermal performances in a linear vane cascade are compared between an array of simple cylindrical holes and an array of diffused-cylindrical holes by employing them in the cascade upstream endwall. The objectives are to increase the aerothermal performance of the cylindrical holes in the gas-turbine passage film cooling. The measurements of the temperature, velocity, flow angle, and total-pressure losses are obtained at the inlet Reynolds number of [Formula: see text], as well as the coolant-to-mainstream density ratio of 1.0 and temperature ratios between 0.94 and 1.0. Four inlet blowing ratios of film-cooling flow are tested. The results show less coolant migration into the boundary layer and passage vortex for the diffused holes than for the cylindrical holes. The passage vortex becomes weaker, and the overall total-pressure losses at the passage exit are lower for the diffused holes. The local and average adiabatic film-cooling effectivenesses along the endwall are always higher for the diffused holes.
为了克服圆柱形孔在膜冷却中的缺点,在级联研究中采用了复杂几何形状的扇形扩散孔。本实验采用了一种用于膜冷却的扩散孔的新设计,该扩散孔是通过仅在正向方向上平滑地扩散圆柱形孔而形成的。通过在叶栅上游端壁中采用简单圆柱孔阵列和扩散圆柱孔阵列,比较了线性叶片叶栅中的气动热性能。目的是提高燃气轮机通道膜冷却中圆柱形孔的气动热性能。温度、速度、流量角和总压力损失的测量值是在[公式:见正文]的入口雷诺数、1.0的冷却剂与主流密度比和0.94至1.0之间的温度比下获得的。测试了薄膜冷却流的四种入口吹风比。结果表明,与圆柱形孔相比,扩散孔的冷却剂迁移到边界层和通道涡流较少。通道涡流变弱,对于扩散孔,通道出口处的总压力损失较低。对于扩散孔,沿端壁的局部和平均绝热膜冷却效率总是较高。
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引用次数: 1
Natural Convection Instabilities Using the Lattice Boltzmann Method: Cavity Aspect Ratio Effect 利用晶格玻尔兹曼方法研究自然对流的不稳定性:空腔宽高比效应
IF 2.1 4区 工程技术 Q2 Physics and Astronomy Pub Date : 2023-03-01 DOI: 10.2514/1.t6690
El Mehdi Berra, M. Faraji
In this paper, the natural convection instability flows in a partial heating cavity filled with air and cooled by the top wall are numerically investigated using the lattice Boltzmann method; and the cavity is partially heated and contains a heat source from below that is presented as an electronic component. To track the cavity aspect ratio effect on the heat transfer over time, first, a series of numerical simulations is completed by varying the aspect ratio of the cavity from [Formula: see text] to [Formula: see text]. The results show that the change in aspect ratio has a noticeable impact on the heat transfer behavior, specifically on the temperature distribution in the cavity, and the numerical results obtained indicate two different temperature distribution regimes: a stable steady regime, and a stable oscillatory regime. In the second step, a numerical simulation is done to study the natural convection instability into the cavity for the aspect ratio configuration of [Formula: see text]. The results show that the cavity structure has an important effect on the heat transfer in the cavity. The lattice Boltzmann method choice as a numerical simulation approach is due to its considerable result in fluid flow simulation and also to its simplicity of implementation, and it has become a suitable alternative method for solving fluid dynamics and thermal problems, as well as challenged traditional methods in many sectors by its simplicity of implementation.
本文采用格子Boltzmann方法,数值研究了由顶壁冷却的局部加热空腔中的自然对流不稳定流动;并且空腔被部分加热并且包含来自下方的热源,该热源被呈现为电子部件。为了跟踪空腔纵横比随时间对传热的影响,首先,通过将空腔的纵横比从[公式:见正文]变为[公式:见图正文]来完成一系列数值模拟。结果表明,长宽比的变化对传热行为,特别是空腔内的温度分布有显著影响,所获得的数值结果表明了两种不同的温度分布状态:稳定稳定状态和稳定振荡状态。在第二步中,对[公式:见正文]的纵横比配置进行了数值模拟,以研究进入空腔的自然对流不稳定性。结果表明,空腔结构对空腔内的传热有重要影响。选择格子Boltzmann方法作为一种数值模拟方法是因为它在流体流动模拟中取得了可观的结果,也因为它的实现简单,它已经成为解决流体动力学和热问题的一种合适的替代方法,并因其实现的简单性而挑战了许多领域的传统方法。
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引用次数: 0
Experimental and Analytical Study on the Liquid Film by Jet–Wall Impingement 射流冲击液膜的实验与分析研究
IF 2.1 4区 工程技术 Q2 Physics and Astronomy Pub Date : 2023-02-27 DOI: 10.2514/1.t6656
Chuansheng Liu, Chenglong Tang, Qingchen Ma, Zuohua Huang, Peng Zhang, Fengyun Zhang
Liquid film cooling by jet–wall impingement on the combustor wall is commonly used in small rocket engines. The heat transfer mechanism inside the liquid film is closely related to the film flow. Therefore, we establish a comprehensive analytical model with reasonable assumptions for the liquid film flow by inclined jet–wall impingement, and we validate it through a series of experiments. It is found that the predicted liquid film dimensions agree well with the experimental results. As the impingement angle increases from 30 to 60 deg, the shape of the liquid film turns from an oval to a circle. With the increase of the impingement velocity from 7.8 to [Formula: see text], the width, length, and area of the liquid film increase. The wall roughness [Formula: see text] ranges from 6.3 to [Formula: see text], which shows negligible effects on the liquid film dimensions. As the surface tension increases from 36.03 to 67.13 mN/m and the viscosity increases from 1 to [Formula: see text], the dimensions of the liquid film decrease. The effect of viscosity is more significant than surface tension within the scope of this experiment. Finally, an empirical correlation for the three investigated film dimensional parameters is proposed.
在小型火箭发动机中,通常使用喷射壁撞击燃烧室壁的液膜冷却。液膜内部的传热机理与液膜流动密切相关。因此,我们建立了一个具有合理假设的倾斜射流-壁面冲击液膜流动的综合分析模型,并通过一系列实验进行了验证。结果表明,预测的液膜尺寸与实验结果吻合较好。当冲击角度从30度增加到60度时,液膜的形状从椭圆形变为圆形。随着冲击速度从7.8增加到[公式:见正文],液膜的宽度、长度和面积都会增加。壁粗糙度[公式:见正文]范围为6.3至[公式:参见正文],其对液膜尺寸的影响可忽略不计。随着表面张力从36.03增加到67.13mN/m,粘度从1增加到[公式:见正文],液膜的尺寸减小。在本实验范围内,粘度的影响比表面张力更显著。最后,提出了所研究的三个薄膜尺寸参数的经验相关性。
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引用次数: 1
Temperature Rise Characteristics and Experimental Study of Magnetorheological Dampers Under Different Excitations 不同激励下磁流变阻尼器温升特性及实验研究
IF 2.1 4区 工程技术 Q2 Physics and Astronomy Pub Date : 2023-02-27 DOI: 10.2514/1.t6710
Liang Zhen, Yongbao Feng, Xiaoxia Han, Zhenhua Zhang
The magnetorheological damper converts the mechanical energy of vibration into its own thermal energy, and the thermodynamic energy is expressed as the temperature rise. In this study, according to the principle of temperature rise, the temperature rise of the magnetorheological damper is established theoretical model by using the simplified one-dimensional heat transfer model of a fluid element and the lumped parameter method under the action of sine harmonic wave motion and triangular wave motion, as well as using the finite element software COMSOL to simulate the internal temperature fields of the damper. The results show that the temperature values of the damper are different, there are high-temperature areas and low-temperature areas, and the temperature rise mainly comes from the heating of the coil. The different frequency and amplitude of the excitation signal, as well as the input current, will affect the internal temperature of the damper. The temperature rise increases with the increase of input current, amplitude, and frequency, which is verified on the built testbench for the temperature rise characteristics. The change trend of the theoretical calculated value, the simulated value, and the tested value is consistent; and there is an error within the allowable range. By comparison, the temperature rise trend is basically the same for the three methods; but, when comparing with the application of sine harmonic wave motion, the temperature rise of the magnetorheological damper is 5°C higher than the triangular wave motion under the same operating condition.
磁流变阻尼器将振动的机械能转化为自身的热能,并将热力学能表示为温升。本研究根据温升原理,采用简化的流体单元一维传热模型和集总参数法,在正弦谐波运动和三角波运动作用下,建立磁流变阻尼器温升的理论模型,并利用有限元软件COMSOL对阻尼器内部温度场进行模拟。结果表明,阻尼器的温度值不同,存在高温区和低温区,温升主要来自盘管的加热。激励信号的不同频率和幅值,以及输入电流的不同,都会影响阻尼器的内部温度。温升随输入电流、幅值和频率的增大而增大,并在搭建的温升特性试验台上得到验证。理论计算值、模拟值与试验值的变化趋势一致;在允许范围内存在误差。通过对比,三种方法的升温趋势基本一致;但与正弦谐波运动的应用相比,在相同工作条件下,磁流变阻尼器的温升比三角波运动高5℃。
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引用次数: 0
Absolute Measurements of Air Shock-Layer Radiation in the T6 Aluminium Shock Tube T6铝激波管内空气激波层辐射的绝对测量
IF 2.1 4区 工程技术 Q2 Physics and Astronomy Pub Date : 2023-02-21 DOI: 10.2514/1.t6693
P. Collen, Alex B. Glenn, L. Doherty, M. McGilvray
This paper presents the first experimental measurements of shock-layer radiation from a new high-enthalpy ground-test facility: the T6 Aluminium Shock Tube mode. A dual-channel imaging emission spectroscopy system was used to record spatially and spectrally resolved, absolute radiation data from air shock layers at velocities ranging from 7 to [Formula: see text]. The presented conditions are designed to provide overlap with other experimental datasets in the literature, from both the NASA Electric Arc Shock Tube and an atmospheric plasma torch. Comparisons with these data (as well as computational tools) was favorable, thereby benchmarking the data from the new shock tube against established sources. The measurements made in this paper also confirm that T6 is now the first European facility capable of performing such superorbital shock-layer radiation studies, thereby providing a new capability to support current and future missions in the solar system.
本文介绍了一种新的高焓地面试验设备T6铝激波管模式对激波层辐射的首次实验测量。双通道成像发射光谱系统用于记录来自空气冲击层的空间和光谱分辨率的绝对辐射数据,速度范围从7到[公式:见正文]。所提出的条件旨在提供与文献中其他实验数据集的重叠,这些数据集来自NASA电弧冲击管和大气等离子体炬。与这些数据(以及计算工具)的比较是有利的,从而将新冲击管的数据与现有来源进行了比较。本文中的测量结果还证实,T6现在是第一个能够进行超轨道冲击层辐射研究的欧洲设施,从而为支持太阳系当前和未来的任务提供了新的能力。
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引用次数: 1
Analysis of Shock Deceleration Effects in the NASA Electric Arc Shock Tube NASA电弧激波管的减震效果分析
IF 2.1 4区 工程技术 Q2 Physics and Astronomy Pub Date : 2023-02-21 DOI: 10.2514/1.t6619
P. Collen, L. di Mare, M. McGilvray, M. Satchell
Complex processes related to nonequilibrium thermochemistry and radiation are a fundamental aspect of atmospheric entry flowfields. Shock tubes provide a means of generating test gas conditions analogous to those found on the stagnation line of flight shock layers, which allows extraction of thermochemical rates and radiative intensities. Currently, the NASA Electric Arc Shock Tube (EAST) is the best source of such data. Although simple in principle, nuances of these experimental facilities can affect the observed results. Notably, electron densities and radiance levels in excess of equilibrium predictions have been observed at EAST for many years. The deceleration of the shock as it passes along the tube has been posited as a source of these discrepancies. In this work, a recently developed numerical methodology (LASTA) is applied to these results from the literature. Using the experimental shock speed profile as an input, trends in postshock electron density are computed. Radiance throughout the shock layer is also predicted by coupling the simulation to the NASA NEQAIR code. It is shown that the predictions of LASTA provide a good match to the magnitudes and trends of the experimental differences, confirming shock speed deceleration as their cause.
与非平衡热化学和辐射有关的复杂过程是大气入口流场的一个基本方面。激波管提供了一种产生测试气体条件的方法,类似于在飞行激波层的停滞线上发现的条件,它允许提取热化学速率和辐射强度。目前,美国宇航局的电弧激波管(EAST)是这类数据的最佳来源。虽然原理简单,但这些实验设备的细微差别会影响观察结果。值得注意的是,多年来在EAST观测到的电子密度和辐射水平超过了平衡预测。当激波沿着管道传递时的减速被假定为这些差异的来源。在这项工作中,最近发展的数值方法(LASTA)应用于这些结果从文献。利用实验激波速度曲线作为输入,计算了激波后电子密度的变化趋势。通过将模拟与NASA NEQAIR代码耦合,还预测了整个激波层的辐射。结果表明,LASTA的预测结果与实验差异的幅度和趋势吻合较好,证实了冲击速度减速是导致差异的原因。
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引用次数: 0
Computational and Experimental Study of Nonequilibrium Flow in Plasma Wind Tunnel 等离子体风洞中非平衡流动的计算与实验研究
IF 2.1 4区 工程技术 Q2 Physics and Astronomy Pub Date : 2023-02-12 DOI: 10.2514/1.t6357
V. Unnikrishnan, N. Yadava, N. Virani, J. Ghosh, N. Sreenivas, L. Aravindakshan Pillai, K. Bodi
The present work examines the thermochemical nonequilibrium flow in the freestream and shock layer of the Plasma Wind Tunnel Facility using experiments and computations. Computational studies were performed using the open-source solver [Formula: see text], which was validated using the NASA Interaction Heating Facility case. Two chemical reaction models were used to compute the nonequilibrium state of air, composed of six species ([Formula: see text], [Formula: see text], NO, N, O, Ar). Optical emission spectroscopy was employed to experimentally capture the [Formula: see text] first positive system emission from the freestream and molecular CN vibration bands emissions in the shock region. The Boltzmann plot method was employed to estimate the vibrational temperatures from the measured spectra. The measured vibrational temperatures in the freestream for two different transitions of [Formula: see text] agree with one another, which shows that the vibrational modes obey the Boltzmann distribution for the conditions considered in this study. The vibrational temperatures computed using [Formula: see text] in the nozzle freestream and the shock layer for the Plasma Wind Tunnel conditions agree with the values obtained from optical emission spectroscopy.
本工作通过实验和计算研究了等离子体风洞设备自由流和冲击层中的热化学非平衡流动。计算研究是使用开源求解器[公式:见正文]进行的,该求解器使用NASA交互加热设施案例进行了验证。使用两个化学反应模型来计算空气的非平衡状态,空气由六种物质组成([公式:见正文],[公式:参见正文],NO,N,O,Ar)。光学发射光谱用于实验捕获[公式:见正文]自由流的第一个正系统发射和冲击区的分子CN振动带发射。采用玻尔兹曼图方法从测量的光谱中估计振动温度。[公式:见正文]的两个不同跃迁在自由流中测得的振动温度彼此一致,这表明在本研究中考虑的条件下,振动模式服从玻尔兹曼分布。在等离子体风洞条件下,使用[公式:见正文]计算的喷嘴自由流和冲击层中的振动温度与从光学发射光谱获得的值一致。
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引用次数: 0
Experimental Study of Dynamic Icing Process on a Pitot Probe Model 皮托管探针模型动态结冰过程的实验研究
IF 2.1 4区 工程技术 Q2 Physics and Astronomy Pub Date : 2023-02-01 DOI: 10.2514/1.t6782
Haiyang Hu, Faisal Al-Masri, L. Tian, Hui Hu
An experimental study was conducted to characterize the dynamic ice accretion process over the surface of a typical aeronautic Pitot probe model under different icing conditions. The experimental study was conducted in the Icing Research Tunnel available at Iowa State University. While a high-speed imaging system was used to record the dynamic ice accretion process, a three-dimensional (3D) scanning system was also used to measure the 3D shapes of the ice layers accreted on the test model. While opaque and grainy ice structures were found to accrete mainly along the wedge-shaped lip of the front port and over the front surface of the probe holder under a dry rime icing condition, much more complicated ice structures with transparent and glazy appearance were observed to cover almost entire surface of the Pitot probe under a wet glaze icing condition. While a flower-like ice structure was found to grow rapidly along the front port lip, multiple irregular-shaped ice structures accreted over the probe holder under a mixed icing condition. The characteristics of the icing process under different icing conditions were compared in terms of 3D shapes of the ice structures, the profiles of the accreted ice layers, the ice blockage to the front port, and the total ice mass on the Pitot probe model. The acquired ice accretion images were correlated with the 3D ice shape measurements to elucidate the underlying icing physics.
对不同结冰条件下典型航空皮托探测器模型表面的动态积冰过程进行了实验研究。实验研究是在爱荷华州立大学的结冰研究隧道中进行的。在使用高速成像系统记录动态积冰过程的同时,还使用三维(3D)扫描系统测量试验模型上积冰层的3D形状。虽然在干霜结冰条件下,发现不透明和颗粒状的冰结构主要沿着前端口的楔形唇缘和探头支架的前表面堆积,但在湿釉结冰条件下观察到具有透明和光滑外观的更复杂的冰结构几乎覆盖了皮托管探头的整个表面。虽然发现一个花朵状的冰结构沿着前端口边缘快速生长,但在混合结冰条件下,多个不规则形状的冰结构在探针支架上堆积。比较了不同结冰条件下结冰过程的特征,包括冰结构的三维形状、堆积冰层的轮廓、前端口的冰堵塞以及皮托探测器模型上的总冰质量。获取的积冰图像与3D冰形测量值相关联,以阐明潜在的结冰物理。
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引用次数: 0
Mixed-Convection Coupled with Thermal-Radiation in a Ventilated Horizontal Channel Containing Different Electronic Components 含有不同电子元件的通风水平通道中的混合对流与热辐射耦合
IF 2.1 4区 工程技术 Q2 Physics and Astronomy Pub Date : 2023-01-16 DOI: 10.2514/1.t6659
R. Hidki, L. El moutaouakil, M. Boukendil, Z. Charqui, Z. Zrikem
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引用次数: 0
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Journal of Thermophysics and Heat Transfer
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