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A laminar supersonic boundary layer under the conditions of diffusive hydrogen-air flame and its stability 扩散氢气-空气火焰条件下的层流超音速边界层及其稳定性
IF 0.5 4区 工程技术 Q4 ENGINEERING, AEROSPACE Pub Date : 2024-03-20 DOI: 10.1134/S0869864323060124
S. A. Gaponov, S. O. Morozov, A. N. Semenov

The problem of hydrodynamic stability of a boundary layer with diffusion combustion is formulated in the Dan–Lin–Alekseev approximation and at constant Prandtl and Schmidt numbers; it is reduced to solving a system of the tenth-order ordinary differential equations with homogeneous boundary conditions. With Lewis numbers equal to unity, it may be lowered to the eighth order. In the inviscid approximation, the stability problem is reduced to the integration of a single second-order differential equation.

Based on the obtained stability equations and calculations of stationary flow parameters, the stability of a supersonic boundary layer with diffusive combustion on a permeable plate with hydrogen supply through its pores is studied for the first time by direct numerical modeling. With the Mach number M = 2, the possibility of flame flow stabilization is established using calculations. It is shown that within the framework of the inviscid theory of stability, it is possible to obtain quite reliable data on the maximum degrees of the growth of disturbances.

在丹-林-阿列克谢耶夫近似条件下,在普朗特数和施密特数不变的情况下,提出了具有扩散燃烧的边界层的流体力学稳定性问题;该问题简化为求解具有同质边界条件的十阶常微分方程组。当路易斯数等于一的时候,可以降到八阶。在不粘性近似条件下,稳定性问题简化为一个二阶微分方程的积分。根据所获得的稳定性方程和静止流参数计算,首次通过直接数值建模研究了通过孔隙供氢的渗透板上扩散燃烧的超音速边界层的稳定性。当马赫数 M = 2 时,通过计算确定了火焰流稳定的可能性。结果表明,在不粘性稳定理论的框架内,有可能获得关于扰动增长最大程度的相当可靠的数据。
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引用次数: 0
Simulation of heating of the sensitive element of the heat flux sensors in a high-velocity flow under variable input conditions 模拟在可变输入条件下高速气流中热流传感器敏感元件的加热过程
IF 0.5 4区 工程技术 Q4 ENGINEERING, AEROSPACE Pub Date : 2024-03-20 DOI: 10.1134/S086986432306001X
I. R. Vasnev, M. A. Goldfeld, N. N. Fedorova

The paper presents the results of numerical simulations of high-velocity turbulent air flows in a plane channel with a variable cross section exhibiting sudden expansion with allowance for coupled heat transfer with copper plates modeling the sensitive elements of heat flux sensors. The simulations are performed for conditions of a high-enthalpy short-duration wind tunnel whose specific features are the short duration of the test regime and unsteady “falling” conditions at the model channel entrance. The wave structure of the supersonic flow, which affects the heat fluxes at the walls, is analyzed for various Mach numbers at the model channel entrance. The numerical algorithm is validated on the basis of experimental data on heating of the sensitive elements of heat flux sensors for unsteady input conditions at the channel entrance. The influence of the Mach number, static parameters, and stagnation parameters on the rate of heating of the sensitive elements located at various points in the channel is studied numerically. The heat fluxes calculated under constant and “falling” conditions at the channel entrance are compared. It is shown that the accuracy of heat flux modeling can be increased by taking into account the intensity of oscillations of the flow parameters and their changes along the channel.

本文介绍了在一个横截面可变的平面通道中的高速湍流气流的数值模拟结果,该通道表现出突然膨胀的特点,并考虑了与模拟热通量传感器敏感元件的铜板的耦合传热。模拟是在高焓短时风洞的条件下进行的,该风洞的特点是试验时间短,模型通道入口处的 "下降 "条件不稳定。针对模型通道入口处的不同马赫数,分析了影响壁面热通量的超音速流波浪结构。根据热通量传感器敏感元件在通道入口处非稳定输入条件下的加热实验数据,对数值算法进行了验证。数值研究了马赫数、静态参数和停滞参数对位于通道各点的敏感元件加热速率的影响。比较了在通道入口处恒定和 "下降 "条件下计算得出的热通量。结果表明,考虑到水流参数的振荡强度及其沿水道的变化,可以提高热通量建模的精度。
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引用次数: 0
Experimental study of sizes and velocities of the droplets produced by water injection system with compressed-air atomizer into the intake manifold of an internal combustion engine applying the optic methods 应用光学方法对带有压缩空气雾化器的水喷射系统在内燃机进气歧管中产生的液滴的大小和速度进行实验研究
IF 0.5 4区 工程技术 Q4 ENGINEERING, AEROSPACE Pub Date : 2024-03-20 DOI: 10.1134/S0869864323060136
M. D. Garipov, A. G. Khafizov, R. F. Zinnatullin, A. A. Melkov, V. A. Shayakhmetov, O. A. Gobyzov

The paper studies the quality of water spraying by system with a compressed-air atomizer designed for water injection into the intake manifold of an internal combustion engine. The system consists of a two-cylinder piston compressor providing compression of water-air mixture in the working chambers. The piston compressor has connection to the atomizer through long channels. The droplet sizes were measured through automatic image processing by the Shadow Photography method. The droplet velocity field was measured by 2D-PIV method. Experimental results demonstrated that the injection system offers a high quality of atomization for the air/water mass ratio higher than 0.46. The Sauter mean diameter was no more than 31.1 µm.

本文研究了采用压缩空气雾化器的喷水系统的喷水质量,该雾化器设计用于向内燃机进气歧管喷水。该系统由一个双缸活塞压缩机组成,用于压缩工作腔中的水气混合物。活塞压缩机通过长通道与雾化器相连。液滴大小是通过阴影摄影法进行自动图像处理测量的。液滴速度场采用 2D-PIV 方法测量。实验结果表明,当空气/水质量比大于 0.46 时,喷射系统的雾化质量较高。萨特平均直径不超过 31.1 微米。
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引用次数: 0
Thermal conductivity of Novec 7100 in vapor phase 消费及工业专用化学品 7100 在气相中的导热率
IF 0.5 4区 工程技术 Q4 ENGINEERING, AEROSPACE Pub Date : 2024-02-13 DOI: 10.1134/S0869864323050116
E. P. Raschektaeva, S. V. Stankus

Thermal conductivity of a Novec 7100 fluid sample was measured by the steady-state method of coaxial cylinders. Experiments were performed in the temperature range 350–385 K and pressure range 0.12–0.21 MPa. The error for experimental data on thermal conductivity is about 1.5–2.5 %. The error in measuring temperature and pressure was less than 0.05 K and 4 kPa, correspondingly. The general equation for calculating the thermal conductivity as a function of pressure and temperature was formulated. Thermal conductivity was defined for the ideal gas state. A previously developed approach was tested in application for a single-measurement prediction of thermal conductivity.

摘要 采用同轴圆柱体稳态法测量了消费及工业专用化学品 7100 流体样品的导热性。实验的温度范围为 350-385 K,压力范围为 0.12-0.21 MPa。热导率实验数据的误差约为 1.5-2.5%。温度和压力测量误差分别小于 0.05 K 和 4 kPa。制定了计算导热系数与压力和温度关系的一般公式。热导率是为理想气体状态定义的。对之前开发的方法进行了测试,以应用于热导率的单次测量预测。
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引用次数: 0
Density and thermal expansion of indium–lead melts 铟铅熔体的密度和热膨胀
IF 0.5 4区 工程技术 Q4 ENGINEERING, AEROSPACE Pub Date : 2024-02-13 DOI: 10.1134/S0869864323050153
R. N. Abdullaev, R. A. Khairulin, S. V. Stankus

The volumetric properties of liquid indium-lead alloys containing 20 and 33 at. % Pb have been measured using gamma-ray attenuation technique at temperatures from the liquidus line to 880 K. The density changes of these alloys during solid–liquid phase transition have been calculated. The obtained experimental values of the molar volume and the volumetric thermal expansion coefficient of melts and the results of calculations according to the laws for an ideal solution and data of other authors have been compared.

利用伽马射线衰减技术测量了含 20% 和 33% 铅的液态铟铅合金在从液相线到 880 K 的温度范围内的体积特性。计算了这些合金在固-液相变过程中的密度变化。比较了熔体摩尔体积和体积热膨胀系数的实验值、根据理想溶液定律计算的结果以及其他作者的数据。
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引用次数: 0
Influence of the pressure of a propane-butane mixture on the morphology of carbon nanomaterial formed in an arc discharge 丙烷-丁烷混合物的压力对电弧放电形成的碳纳米材料形态的影响
IF 0.5 4区 工程技术 Q4 ENGINEERING, AEROSPACE Pub Date : 2024-02-13 DOI: 10.1134/S0869864323050098
M. A. Morozova, A. V. Ukhina, A. V. Zaikovskii

The morphology of carbon material formed in an arc discharge in a mixture of i-butane, n-butane, and propane when spraying a graphite-nickel electrode was studied. The experiments were carried out with changing the gas medium pressure. Carbon globules, graphene structures, and carbon nanotubes have been discovered. It was found that at pressures of 75 and 400 torr, carbon globules predominate in the resulting materials. At gas pressures of 200 torr, the material collected from the cold screen surface contains both graphene-like structures and significant amounts of carbon nanotubes. The physical reasons influencing the observed phenomena are discussed.

研究了在 i-丁烷、n-丁烷和丙烷混合物中电弧放电时喷涂石墨-镍电极所形成的碳材料的形态。实验是在改变气体介质压力的情况下进行的。发现了碳球、石墨烯结构和碳纳米管。实验发现,在压力为 75 和 400 托时,生成的材料中以碳球为主。当气体压力为 200 托时,从冷筛表面收集到的材料中既有类似石墨烯的结构,也有大量的碳纳米管。本文讨论了影响观察到的现象的物理原因。
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引用次数: 0
Study of a regenerative cooling system while using heat-conductive metal nanoparticle suspension in n-decane 使用正癸烷中的导热金属纳米颗粒悬浮液的再生冷却系统研究
IF 0.5 4区 工程技术 Q4 ENGINEERING, AEROSPACE Pub Date : 2024-02-13 DOI: 10.1134/S0869864323050104
K. Yu. Arefiev, A. M. Saveliev, A. V. Voronetskii, S. V. Kruchkov

The paper presents the calculation estimates for efficiency of regenerative cooling for a model cylinder-shaped flow duct using a suspension of heat-conductive metal nanoparticles in n-decane as fuel/coolant. We adapted a standard mathematical model of conjugated heat transfer that accounts for thermophysical properties of the metal nanoparticle suspension and n-decane. The data are presented for heating up the nanosuspension and the model duct walls for the cases of different content of metal nanoparticles in nanosuspension. There exists a range beneficial for heat transfer from n-decane.

本文介绍了使用正癸烷中的导热金属纳米颗粒悬浮液作为燃料/冷却剂的圆筒形流动管道模型的再生冷却效率的计算结果。我们采用了一个标准的共轭传热数学模型,该模型考虑了金属纳米颗粒悬浮液和正癸烷的热物理性质。我们提供了在纳米悬浮液中金属纳米颗粒含量不同的情况下加热纳米悬浮液和模型管道壁的数据。结果表明,正癸烷的热量传递在一定范围内是有益的。
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引用次数: 0
Boundary-layer control on a body of revolution with a large aspect ratio by means of distributed air blowing 通过分布式吹气对大长径比旋转体进行边界层控制
IF 0.5 4区 工程技术 Q4 ENGINEERING, AEROSPACE Pub Date : 2024-02-13 DOI: 10.1134/S0869864323050037
V. I. Kornilov

Results of studying the process of air blowing through a perforated section of the surface on an axisymmetric body with an aspect ratio of 25.3 in an incompressible flow with the Reynolds number ReL = 4.36·106 are reported. The blowing coefficient Cb is varied in the interval from zero to 0.00885. It is shown that distributed blowing through a perforated wall with improved geometry ensures a significant gain in friction drag as compared to that for the base configuration. Beginning from the frontal boundary of this section and further downstream, stable reduction of local friction is observed, which reaches 72 % directly in the region of blowing with the maximum intensity. In view of the energy expenses on the blowing process, the degree of energy saving can reach 1.4 to 6.1 % for the blowing region being located on the cylindrical part of the model. The efficiency of this method of boundary layer control can be refined by a more accurate determination of the contribution of the drag component induced by the pressure and friction forces on the frontal part of the body. The importance of estimating the possibility of using the proposed approach for the case of air blowing through a surface section on the frontal part of the body is noted.

报告了在雷诺数 ReL = 4.36-106 的不可压缩流中,空气吹过一个长宽比为 25.3 的轴对称体表面的穿孔部分的过程的研究结果。吹气系数 Cb 在零到 0.00885 之间变化。结果表明,与基本配置相比,通过改进几何形状的穿孔壁进行分布式吹气可确保摩擦阻力的显著增加。从该断面的正面边界开始,再向下游延伸,可以观察到局部摩擦力的稳定减小,在最大强度的吹风区域直接达到 72%。考虑到吹风过程中的能量消耗,位于模型圆柱部分的吹风区域的节能程度可达 1.4% 至 6.1%。这种边界层控制方法的效率可以通过更精确地确定车身正面压力和摩擦力引起的阻力分量来加以完善。需要指出的是,在空气吹过车身前部表面部分的情况下,估计使用拟议方法的可能性非常重要。
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引用次数: 0
Mathematical modeling of self-excited oscillations over the pitch of a conical-spherical body at Mach number M = 1.75 using the forced-oscillation hypothesis 利用强迫振荡假说对马赫数 M = 1.75 时锥球体俯仰自激振荡进行数学建模
IF 0.5 4区 工程技术 Q4 ENGINEERING, AEROSPACE Pub Date : 2024-02-13 DOI: 10.1134/S0869864323050086
E. A. Chasovnikov

With the aim to model the self-excited oscillations of a body, a hypothesis is proposed for the formation of periodic bottom-wake vortex structures whose frequency coincides with the natural frequency of oscillations of the body, and the force effect of the oscillations on the body is mathematically described with a harmonic function of time. Analytical formulas for aerodynamic derivatives and equivalent aerodynamic derivatives are obtained. It is shown that the mathematical model satisfactorily describes the dependence of the pitch angle on time and the dependence of the equivalent aerodynamic derivatives on the amplitude of oscillations for two moments of inertia of the body. The mathematical model predicts a hyperbolic law for the dependence of the amplitude of self-excited oscillations on the reduced frequency.

为了模拟物体的自激振荡,提出了形成周期性底摇涡旋结构的假设,其频率与物体振荡的固有频率相吻合,振荡对物体的力效应用时间的谐函数进行数学描述。得到了空气动力导数和等效空气动力导数的解析公式。结果表明,该数学模型能令人满意地描述俯仰角对时间的依赖关系,以及在机体两个惯性矩的情况下,等效空气动力学导数对振荡振幅的依赖关系。数学模型预测了自激振荡振幅对降低频率的双曲线规律。
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引用次数: 0
Study of the transient gas outflow from a container 容器中瞬时气体流出研究
IF 0.5 4区 工程技术 Q4 ENGINEERING, AEROSPACE Pub Date : 2024-02-13 DOI: 10.1134/S0869864323050050
T. A. Gimon, V. I. Zvegintsev, N. N. Fedorova

An experimental study of the flow of air from a container through throttling tubes of various configurations with characteristic times from 0.6 to 9 s was carried out. The equivalent container-outlet area was determined based on the ratio of the length of the throttling tube to its nominal diameter. It was found that during the outflow, the gas temperature inside the container decreased by 10–15 %, which value differs substantially from the theoretical estimate of 60 % obtained assuming that the process was adiabatic. Based on the results of measuring the gas pressure and temperature in the container, a method is proposed for calculating the heat fluxes on the walls.

摘要 对来自容器的气流通过特征时间从 0.6 秒到 9 秒的各种结构的节流管进行了实验研究。根据节流管长度与其标称直径之比,确定了等效容器出口面积。结果发现,在流出过程中,容器内的气体温度降低了 10-15%,这一数值与假定该过程为绝热过程而得出的 60% 的理论估计值相差很大。根据测量容器内气体压力和温度的结果,提出了一种计算壁上热通量的方法。
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引用次数: 0
期刊
Thermophysics and Aeromechanics
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