气相规则胞格爆轰起爆与传播的统一框架理论

本文回顾了气相规则胞格爆轰起爆与传播研究的发展,根据中国科学院高温气体动力学重点实验室在爆轰现象方面的研究进展,提出了气相规则胞格爆轰波起爆和传播的统一框架理论。该框架理论由一个波传播/化学反应相互作用机制,两个基本物理过程(热点和化学反应带加速),三个临界状态(临界传播状态、临界起爆状态和临界胞格尺度)等六个关键要素构成。应用五个典型物理算例,界定了这些关键要素的物理机制、表现特性及其客观存在性。应用这个爆轰波统一框架理论,本文成功地解释了经典爆轰理论、应用CFD技术获得的多维爆轰波结果和实验观察到的胞格爆轰现象依据的关键要素。虽然爆轰波的三个临界状态需要进一步的定量化研究,但是应用框架理论解释已经获得的爆轰波研究结果表现的统一性及其对深入研究爆轰现象的预测性表明了该框架理论对于开展深入的爆轰物理具有重要意义。

污染空气对乙烯燃料超燃冲压发动机燃烧室流场影响的数值评估

由于纯净空气的超燃燃烧室试验条件比较缺乏，污染空气效应对试验结果的影响往往通过CFD计算来评估。本文通过数值模拟中国科学院力学研究所高温气动实验室的乙烯燃料超燃燃烧室试验，来数值评估来流空气污染效应对试验结果的影响。分别计算了燃烧室入口来流马赫数1.8和2.5的工况，计算结果表明：马赫1.8情况下，空气的污染成分有利于燃烧，纯净空气情况下由于凹腔内处于富油情况燃烧增压不够；马赫2.5情况下，空气的污染成分对燃烧影响不大。

超声速平板绕流的全流域阻力特性研究

超声速流动中摩擦阻力的准确预测一直是气动研究中的难点。本文以零攻角的平板绕流为对象，结合传统的CFD方法求解Navier-Stokes方程和直接模拟Monte-Carlo（DSMC）方法模拟粒子的微观运动，研究平板在超声速来流下的全流域阻力特性。研究发现，在超声速流中会产生激波-边界层相互干扰作用并随着来流马赫数的增加而加强，同时平板前缘存在非平衡效应显著的区域；努森数的增大使激波和边界层均增厚，粘性作用增强，非平衡区的范围增大，非平衡强度增强，而激波强度减弱；最后通过拟合连续流条件下的摩阻系数和修正自由分子流结果，结合桥函数，获得了全流域范围内均有效的平板阻力系数表达式。

交变流动中压力速度之间相位差对突变截面损失的影响分析

从弱非线性热声理论出发,给出交变流动中突变截面阻力系数的定义以及考察方法。通过PIV(粒子成像测速仪)测量与CFD计算结果的对比,验证了CFD计算结果的可靠性。进而利用CFD模拟考察了交变流动中压力与速度之间相位差对突变截面局部损失的影响,观察到产生这种影响的流场内部流动机制。分析表明,阻力特性确实对声场压力与速度之间的相位差存在依赖性,但这种依赖性会随着非线性的增强而减少。

Hydroelastic dynamic characteristics of a slender axis-symmetric body

The slender axis-symmetric submarine body moving in the vertical plane is the object of our investigation. A coupling model is developed where displacements of a solid body as a Euler beam (consisting of rigid motions and elastic deformations) and fluid pressures are employed as basic independent variables, including the interaction between hydrodynamic forces and structure dynamic forces. Firstly the hydrodynamic forces, depending on and conversely influencing body motions, are taken into account as the governing equations. The expressions of fluid pressure are derived based on the potential theory. The characteristics of fluid pressure, including its components, distribution and effect on structure dynamics, are analyzed. Then the coupling model is solved numerically by means of a finite element method (FEM). This avoids the complicacy, combining CFD (fluid) and FEM (structure), of direct numerical simulation, and allows the body with a non-strict ideal shape so as to be more suitable for practical engineering. An illustrative example is given in which the hydroelastic dynamic characteristics, natural frequencies and modes of a submarine body are analyzed and compared with experimental results. Satisfactory agreement is observed and the model presented in this paper is shown to be valid.

采用改进尾流振子模型的柔性海洋立管的涡激振动响应分析

建立了柔性杆件在非均匀流作用下的涡激振动响应预测模型, 考虑了涡激振动锁频阶段流体附加质量的变化, 以及振动响应和来流简缩速度的非线性关系. 该模型通过经验公式结合迭代求解的方式, 计算方便、速度快, 避免了数值计算(CFD)的繁琐, 较为适合于海洋工程实际应用. 与试验和数值结果的比较表明采用该文提出的计算模型, 可以更合理、准确地给出结构涡激振动响应. 最后, 结合实际平台参数, 进行了柔性立管在非均匀流场的作用下的涡激振动响应分析, 并研究了立管的预张力、流场分布等参数的影响. 分析结果表明: 随着立管张力和流场分布的改变, 各阶模态锁频区域发生了变化, 从而改变了结构的总体响应

细长轴对称体的水弹性振动特性分析

以在水中做纵向平面内运动的细长轴对称体为研究对象.在建立描述流体-结构耦合振动系统的计算模型时,对固体采用位移(包括刚体运动位移和弹性Euler梁振动位移),对流体采用压力作为基本变量,首先建立了考虑流体作用力的结构动力学方程,推导了考虑结构运动的流体压力表达式,分析了水动力载荷的特征:包括水动压力的来源,组成,分布形式与影响范围等.在此基础上给出了描述水中运动物体的位移(结构)-压力(流体)格式的流固耦合系统模型.然后利用有限元数值方法(FEM)对方程进行了求解,克服了解析解对研究对象外形的限制,同时避免了流固耦合直接数值模拟中CFD+FEM的复杂性,对于典型的工程结构非常适用.最后,通过算例给出了水中运动物体的水弹性频率和模态,并将计算结果与试验结果进行了对比,证明了本文计算模型的有效性

风沙两相流中近沙床颗粒应力分析

通过统一的计算流体力学(CFD)与颗粒离散元(DEM)相结合的方法对典型风沙流场中近沙床的颗粒运动进行了二维数值模拟。气相湍流采用了K-E模型，颗粒的碰撞采用了软球模型。对计算结果的统计发现，颗粒的碰撞仅存在于沙床上方7mm以下，但是4$\sim$7mm为过渡层，颗粒穿越过渡层发生的碰撞是随机的。颗粒雷诺应力存在于沙床上方250mm以下，随着高度的增加，颗粒雷诺应力急剧下降。在沙床高度250mm以上，只有气相剪切应力起作用。这时，颗粒的浓度非常低，虽然颗粒和气相之间仍然有速度差，但是由此产生的单位体积曳力很低，因而不会对气相剪切应力造成影响。

PREDICTION OF VORTEX-INDUCED VIBRATION OF FLEXIBLE RISER USING AN IMPROVED WAKE-OSCILLATOR MODEL

Based on improving the wake-oscillator model, an analytical model for vortex-induced vibration (VIV) of flexible riser under non-uniform current is presented, in which the variation of added mass at lock-in and the nonlinear relationship between amplitude of response and reduced velocity are considered. By means of empirical formula combining iteration computation, the improved analytical model can be conveniently programmed into computer code with simpler and faster computation process than CFD so as to be suitable to application of practical engineering. This model is validated by comparing with experimental result and numerical simulation. Our results show that the improved model can predict VIV response and lock-in region more accurately. At last, illustrative examples are given in which the amplitude of response of flexible riser experiencing VIV under action of non-uniform current is calculated and effects of riser tension and flow distribution along span of riser are explored. It is demonstrated that with the variation of tension and flow distribution, lock-in region of mode behaves in different way, and thus the final response is a synthesis of response of locked modes.

NEW METHODOLOGY FOR THE ESTIMATION OF ENERGY CONSUMPTION IN A DOUBLE-TUBE-SOCKET (DTS (R)) PNEUMATIC CONVEYING

A new methodology based on the use of CFD is proposed to estimate the energy consumptions in a DTS (DOUBLE-TUBE-SOCKET) pneumatic conveying. A simple computational program based on this methodology is developed. It can directly give the lowest energy consumption and the compatible gas consumption by only input the distance of conveying and the conveying tonnage. This computational program has been validated through our experimental work.

迷宫流道转角对灌水器抗堵塞性能的影响

以转角分别为45.0°、60.0°、67.5°和75.0°的齿形流道灌水器为研究对象,应用CFD流场速度数值分析、PIV颗粒运动轨迹线和速度观测对比以及浑水抗堵塞测试相结合的方法,研究了转角对灌水器水力性能和抗堵塞能力的影响。结果表明转角与流量系数及流态指数均呈负相关关系,而灌水器的抗堵塞能力随着转角的增加呈下降趋势。综合分析转角对水力性能和抗堵塞性能的影响,提出迷宫流道结构灌水器的合理转角为60.0°。

CFX与USAERO的水下机器人操纵性仿真计算研究

研究了借助计算流体力学软件CFX与USAERO对水下机器人的操纵性进行仿真计算的方法,并将仿真计算结果与模型试验结果对比,验证仿真计算的可行性,指出仿真计算的适用范围.该方法可以对某些现实中难以进行的操纵性试验进行仿真计算,对于研究水下机器人的操纵性尤其是在方案设计阶段的操纵性设计和降低试验成本有一定的现实意义.

水下机器人多功能仿真平台及其鲁棒控制研究

为了辅助水下机器人控制系统的研究和开发，论文第一部分研究和建立水下机器人多功能仿真平台。基于现代仿真技术，先后研制成“7000米载人潜水器”多功能仿真平台HOV7000，“CR-02”6000米自主水下机器人多功能仿真平台CR6000和远程自主水下机器人多功能仿真平台LAUV。该种平台具有缩短研制水下机器人周期、减少试验成本、提高系统安全性和可靠性等特点。该平台的创新点在于水下机器人控制系统的硬件和软件与真实系统的硬件和软件完全一致，在多功能仿真平台上调试后的程序直接作为真实系统的控制程序运行。 论文第二部分针对7000米载人潜水器工作环境的复杂性，水下机器人本身参数摄动、外界扰动、传感器、执行机构、控制器不同程度存在不确定性、非线性和延迟，常规的控制方法一定程度上难以克服上述不确定性的影响等问题，研究了可以克服上述多环节不确定性、适合7000米载人潜水器水下作业场合的强鲁棒控制方法。其创新点为将运算量较大的多输入多输出鲁棒控制算法通过选择适当的加权函数应用于实际的水下机器人控制系统。本论文研究内容如下： 1、利用现代仿真技术研究水下机器人多功能仿真平台的实现方法。深入研究了水下机器人动力学模型、推进系统、海洋环境中海流、海底地形和水下机器人传感器等模型。利用机理仿真法，研究了水下机器人分立件推进系统模型和动力学模型；基于电子海图数据采用曲线/曲面拟合法建立了海流数据库模型，并提出了DTTCGSFD的海底地形生成方法；基于随机仿真法研究了水下机器人传感器的模拟方法；采用相似仿真法研究了基于势流理论、水面进行波、CFD的海流模拟方法和视觉传感器模拟方法；采用综合仿真法建立了一体化推进系统的模型。 2、研制成的水下机器人仿真平台具有下述9个方面的功能：基本原理、设计思想和方法的验证；控制系统软件和硬件的静态和动态调试；系统性能的测试与评价；下水前使命可实现性的全程实时验证；水下使命执行过程的伪在线监视；实时运行过程的离线重现；示教与训练；故障可能原因的仿真分析；演示与汇报。现场试验结果表明，多功能平台上的控制效果与现场湖试和海试的试验结果基本吻合。水下机器人多功能仿真平台的研制成功对于水下机器人的研究开发工作具有很大的实际意义，它使我们的研究工作从基于实际环境研究开发向基于虚拟环境研究开发转变，大大缩短了研究工作的周期，节省了大量的人力、物力和经费。 3、研究了基于MLQG的7000米载人潜水器控制方法。将7000米载人潜水器看作慢时变线性系统，采用带遗忘因子的递推最小二乘辨识算法及平方根算法辨识出水下机器人系统的时变参数，利用LQG控制具有克服零均值白噪声的特点设计2种MLQG鲁棒控制器。仿真试验结果表明MLQG控制算法对水下机器人系统存在海流扰动和参数时变两种不确定性均具有较好的鲁棒性。 4、研究基于混合灵敏度的H∞水下机器人鲁棒控制方法。由于水下机器人系统的模型摄动加权函数、输入加权函数、性能指标加权函数等加权函数的选择是水下机器人系统鲁棒稳定性和鲁棒性能的核心。深入研究并设计出适合于7000米载人潜水器的各加权函数后，将混合灵敏度问题转化为标准H∞问题，采用代数Riccati方程或LMI方法设计了可克服水下机器人多环节同时存在不确定性的鲁棒控制器。通过对频域和时域分析表明H∞鲁棒控制对于提高7000米载人潜水器系统快速性、减小系统稳态误差和克服系统不确定性具有更好的效果。在HOV7000多功能仿真平台上进行的控制系统试验——阶跃响应试验、动力定位试验以及H∞鲁棒控制和PID控制的比较试验验证了上述控制效果。 5、为了克服基于H∞鲁棒控制理论设计的控制器具有保守性的缺点，研究了基于结构奇异值µ的水下机器人鲁棒控制方法。在对结构奇异值µ理论深入研究后，讨论基于结构奇异值µ鲁棒控制和基于混合灵敏度的H∞鲁棒控制在系统模型摄动加权函数、输入加权函数、性能指标加权函数等加权函数的选择方面的区别与联系。设计出各相应加权函数后，采用D-K迭代方法设计了可克服水下机器人多环节同时存在不确定性的控制器参数。频域和时域内的理论分析结果，和HOV7000多功能仿真平台上的试验——系统阶跃响应试验、动力定位试验以及基于结构奇异值µ鲁棒控制与PID控制比较试验结果，表明采用基于结构奇异值µ的水下机器人鲁棒控制方法比基于H∞混合灵敏度的鲁棒控制方法具有更好的鲁棒稳定性和鲁棒性能。

各向异性与非线性介质中弹性波场传播特征研究

The topic of this study is about the propagation features of elastic waves in the anisotropic and nonlinear media by numerical methods with high accuracy and stability. The main achievements of this paper are as followings: Firstly, basing on the third order elastic energy formula, principle of energy conservation and circumvolved matrix method, we firstly reported the equations of non-linear elastic waves with two dimensions and three components in VTI media. Secondly, several conclusions about some numerical methods have been obtained in this paper. Namely, the minimum suitable sample stepth in space is about 1/8-1/12 of the main wavelength in order to distinctly reduce the numerical dispersion resulted from the numerical mehtod, at the same time, the higher order conventional finite difference (CFD) schemes will give little contribution to avoid the numerical solutions error accumulating with time. To get the similar accuracy with the fourth order center finite difference method, the half truncation length of SFFT should be no less than 7. The FDFCT method can present with the numerical solutions without obvious dispersion when the paprameters of FCT is suitable (we think they should be in the scope from 0.0001 to 0.07). Fortunately, the NADM method not only can reported us with the higher order accuracy solutions (higher than that of the fourth order finite difference method and lower than that of the sixth order finite difference method), but also can distinctly reduce the numerical dispersion. Thirdly, basing on the numerial and theoretical analysis, we reported such nonlinear response accumulating with time as waveform aberration, harmonic generation and resonant peak shift shown by the propagation of one- and two-dimensional non-linear elasticwaves in this paper. And then, we drew the conclusion that these nonlinear responses are controlled by the product between nonlinear strength (SN) and the amplitude of the source. At last, the modified FDFCT numerical method presented by this paper is used to model the two-dimensional non-linear elastic waves propagating in VTI media. Subsequently, the wavelet analysis and polarization are adopted to investigate and understand the numerical results. And then, we found the following principles (attention: the nonlinear strength presented by this paper is weak, the thickness of the -nonlinear media is thin (200m), the initial energy of the source is weak and the anisotropy of the media is weak too): The non-linear response shown by the elastic waves in VTI media is anisotropic too; The instantaneous main frequency sections of seismic records resulted from the media with a non-linear layer have about 1/4 to 1/2 changes of the initial main frequency of source with that resulted from the media without non-linear layer; The responses shown by the elasic waves about the anisotropy and nonlinearity have obvious mutual reformation, namely, the non-linear response will be stronger in some directions because of the anisotropy and the anisotropic strength shown by the elastic waves will be stronger when the media is nonlinear.

Trade-off between minimum number of wireless sensors and the accuracy of temperature profile in cold rooms: a model-based framework

Evaluation of temperature distribution in cold rooms is an important consideration in the design of food storage solutions. Two common approaches used in both industry and academia to address this question are the deployment of wireless sensors, and modelling with Computational Fluid Dynamics (CFD). However, for a realworld evaluation of temperature distribution in a cold room, both approaches have their limitations. For wireless sensors, it is economically unfeasible to carry out large-scale deployment (to obtain a high resolution of temperature distribution); while with CFD modelling, it is usually not accurate enough to get a reliable result. In this paper, we propose a model-based framework which combines the wireless sensors technique with CFD modelling technique together to achieve a satisfactory trade-off between minimum number of wireless sensors and the accuracy of temperature profile in cold rooms. A case study is presented to demonstrate the usability of the framework.