0.6米暂冲式跨超声速风洞流场控制系统设计

针对0.6米暂冲式跨超声速风洞结构组成复杂、系统控制精度要求高、运行方式多样和运行安全要求严格的特点，分析了流场控制系统的硬件结构，开展了基于NI LabVIEW开发平台的风洞流场控制软件设计研究工作。重点介绍了控制系统组成、软件的结构和功能设计、信号采集与处理、控制策略和安全策略等内容。应用结果表明：该系统具有调节快、精度高、稳定性好、安全可靠的特点，成功实现了暂冲式跨超声速风洞复杂流程控制系统的应用软件开发。     

遗传算法在跨超声速风洞总压控制中的应用

总压作为风洞控制中的重要流场参数,其调节性能是风洞控制系统能否满足试验要求的重要指标,为提高跨超声速风洞的总压控制水平,需对总压控制策略进行设计。针对某跨超声速风洞对总压控制系统提出的快速性和精确性要求,提出串级控制、智能PID控制和总压分段控制等方法,并利用MATLAB系统辨识工具箱对流场调节阶段的总压系统模型进行了辨识。提出将遗传算法应用于风洞流场调节阶段的PID控制器参数整定中,重点对基于遗传算法的PID控制原理和参数整定步骤进行介绍,并针对遗传算法的遗传算子进行了设计。系统仿真和风洞实际运行情况表明：该方法较常规PID参数整定与优化方法,具有更好的控制性能指标,满足总压控制系统精确性、快速性、鲁棒性等要求,为后续风洞建设和设备改造提供了新方法。     

激波管风洞中全尺寸涡轮试验的若干气动问题

暂冲式涡轮实验台是促进涡轮部件技术进步的关键设施．本文对激波管风洞全尺寸涡轮实验台若干气动问题进行了研究，结果表明：在暂冲式风洞中，涡轮建立稳态流场所需时间正比于涡轮叶排的轴向尺寸和折合流量．激波管风洞、喷管、实验段间匹配非常关键．     

边界层效应影响等离子体气动激励诱导激波机理

 针对小型暂冲式超声速风洞进行的诱导激波实验结果,提出等离子体气动激励诱导激波的机理不仅取决于放电时产生的焦耳热效应,放电区域的边界层厚度也起到了决定性的作用的推论。为进一步验证此思想,在高超声速激波风洞进行了等离子体气动激励诱导激波的实验研究。结果表明,在边界层很薄的情况下,等离子体气动激励能够诱导出斜激波。分别阐述了两种实验条件下诱导激波的机理,证实了边界层效应在等离子体与激波相互作用中起到了决定性作用。     

超声速叶栅实验中空气湿度的影响及临界湿度

一、超声速叶栅风洞试验在空气湿度较大时出现的一些现象和对它的分析 超声速风洞对空气湿度有较严格的限制,以避免在超声速膨胀后,出现凝结现象,破坏均匀流场并使M数显著降低,有时还在试验模型上结冰而改变其几何尺寸. 本文介绍在暂冲下吹式超声速叶栅风洞中进行的实验.空气经过干燥.风洞进口处管内气温比大气温度略高,但通常相差不超过10℃,试验的M数通常为1.3至1.5.试验前对国产SYD-1型数字编码压力传感器进行过校准,测量精度为±0.3％. 经多次吹风试验后,干燥塔内硅胶吸收水份的效能降低,试验时在喷管出口侧壁静压     

超音速涡轮叶栅气动性能实验及分析

利用中国科学院工程热物理研究所和哈尔滨汽轮机厂合建的暂冲式超音速平面叶栅风洞,在详细校核进口流动均匀性、出口流动周期性及叶栅中部流动二元性的基础上,详细测试了三套超音速涡轮叶栅在设计和非设计等三个攻角状态下的气动性能及叶片表面压力分布,为超音速涡轮叶栅的后续研究积累了翔实的实验资料。     

金属烧结丝网在内场消声中的应用

利用试验手段研究暂冲式风洞稳定段内安装不同规格烧结金属丝网对风洞上游控制阀后气流噪声和湍流度抑制作用。试验结果表明:多层金属烧结丝网可在全频段内大幅度降低上游气流的噪声,最大可达21 dB;消声量与金属烧结丝网无量纲的压力损失系数成正比,压力降与金属烧结丝网层数呈现出非线性叠加的结果。另外发现烧结金属烧结丝网对气流速度脉动亦具有突出的抑制效果。例如,试验段马赫数Ma=1:5时,120目26层+160目26层组合烧结金属丝网出口气流速压脉动幅值减小为入口来流的18%,湍流度由11.7%降至3%。因此金属烧结丝网适合于暂冲式风洞的内场降噪。     

新建高焓激波风洞Ma=8飞行模拟条件的实现与超燃实验

针对高Mach数超燃冲压发动机实验能力空缺问题,基于航天十一院新建的FD-21高能脉冲风洞,进行了Ma=8超燃飞行条件的模拟能力设计与调试,获得了总焓2.9 MJ/kg、总压11.01 MPa实验条件,实现了Ma=8、高度31 km飞行条件的风洞模拟.在此基础上,研发了匹配的氢燃料供应及喷注时序控制系统,设计了超燃冲压发动机模型,开展了超燃冲压发动机模型自由射流应用性风洞实验,获得了氢气燃料与空气、氮气超声速气流耦合流动作用下的实验模型壁面压力数据.在当量比近似一致条件下,空气来流对应的燃烧室壁面压力明显高于氮气来流情况,表明氢气在1 ms有效实验时间内完成了与超声速空气来流的混合、点火与燃烧,获得燃烧释热特性,确认了在FD-21高能脉冲风洞开展高Mach数超燃实验是切实可行的,为后续研究奠定了良好的基础.      

一种简易风洞模拟控制系统设计

介绍了简易风洞模拟系统的设计及制作。本设计以XS128单片机为主控芯片,利用涡轮式轴流风机来为小球的运动提供动能。通过在风洞表面安装的CCD传感器来检测小球位置,而后通过PID算法对轴流风机的抽风量进行进一步调校。从而形成一个完整的闭环控制系统,实现对风动系统的模拟。     

叶栅风洞控制方法分析与实现

为解决叶栅风洞气罐容量小气源压力下降快给流场控制带来的难题,采用动态变参数和积分分离PID控制算法实现了叶栅风洞流场快速稳定和目标压力高精度控制目的;以调压阀后压力为控制点,采用叶栅入口压力误差值对控制点压力进行修正的方法,解决了常压和增压试验中控制滞后问题;变参数PID控制和选用具有确定对应关系控制点并对实际误差进行修正的方法,对小型暂冲风洞高精度压力控制和滞后问题的解决具有一定借鉴意义。     

白光和红绿蓝光LED可调光源研制

为了提高LED光源色温和亮度的调节精度和准确度,结合色温由低向高变化时光色所呈现的渐变特点,提出了一种低色温白光LED灯珠、高色温白光LED灯珠加红绿蓝光LED灯珠补偿式调光的方法.将色温分成三个部分进行调节,每个部分选用不同的LED灯珠组合来进行调光.实验结果表明:不同组合情况下的LED光源的初始输出色温相对于目标值的偏差范围在1％以内;亮度可以在保证色温不变的情况下独立进行调节,初始输出值与目标值的偏差范围在1％以内;经过微调之后可以达到目标值;达到了色温和亮度独立调节的要求;光源发光稳定,不会因为长时间工作而影响调节精度.     

Muonic and pionic L- and M-series in carbon and oxygen and the pionic 2p level shift and width of oxygen

Muonic and pionic X-rays of the L- and M-series in C and O have been measured with a Si(Li) detector in the energy range between 7 keV and 60 keV. The target consisted of mylar (C₅H₄O₂). Energies and intensities of 21 transitions have been determined. The strong interaction shift of the pionic 2p level in O was measured and found to be +4.1 ±2.3 eV. The measured width of this level is 11±6 eV. The measured yields have been compared with cascade calculations.     

Visualization and interferometry for cylindrical and spherical sample tomography and profilometry

A technique combining image processing and laser interferometry for visualizing and detecting the deformation of transparent cylindrical and spherical sample is proposed. This deformation includes geometric deformation such as volume transition in profilometry and physical deformation such as refractive index change in tomography. Phase contour lines are used for quantitative analysis and graphical representation of the deformation. This method allows us to visually detect the spatial variation of the deformation field and to evaluate the test quality such as misalignment of optical system. A theoretical analysis using phase contour map to characterize the deformation field is described in detail. A method using phase contour map to qualify the interferometric test is proposed. Analysis of test examples is carried out. Suggestions on using phase contour line method to ameliorate test system design are finally discussed.     

Nonlocal potentials and their exact and approximate local and velocity-dependent equivalents

We show that good approximations to the exact equivalent local potential (ELP) and damping factor of a nonlocal Perey-Buck potential can be calculated in the partial wave WKB approximation of Horiuchi. The exact ELP and damping factor are obtained by means of a method previously given by one of us. We also confirm that an approximate ELP proposed by Bauhoff et al. is of comparable accuracy as the Horiuchi approximation. Thesel-dependent ELP's exhibit reduced attraction in the interior and provide a test for higher order WKB approximations. We subsequently obtain an equivalent velocity dependent potential (EVDP) which is even exactly wave function equivalent to the original nonlocal potential. This almost local potential, unlike the trivial equivalent local potential, is smooth and well-behaved and is therefore particularly useful in nuclear reactions where the off-shell behaviour of the potential is important.     

Quantum and Classical Disparity and Accord

Discrepancies and accords between quantum (QM) and classical mechanics (CM) related to expectation values and periods are generally found for both the harmonic oscillator (SHO) and a free particle in a box (FPB), which may apply generally. These indicate non-locality is expected throughout QM. The FPB energy states violate the Correspondence Principle. Previously unexpected accords are found and proven that 〈x ²〉 _CM =〈x ²〉 _QM and τ _CM =τ _QMb (beat period i.e. beats between the phases for adjoining energy states) for the SHO for all quantum numbers, n. However, for the FPB the beat periods differ at small n. It is shown that a particle’s velocity in an infinite square well varies, no matter how wide the box, nor how far the particle is from the walls. The quantum free particle variances share an indirect commonality with the Aharonov-Bohm and Aharonov-Casher effects in that there is a quantum action in the absence of a force. The concept of an “Expectation Value over a Partial Well Width” is introduced. This paper raises the question as to whether these inconsistencies are undetectable, or can be empirically ascertained. These inherent variances may need to be fixed, or nature is manifestly more non-classical than expected.     

Spin and Statistics and First Principles

It was shown in the early seventies that, in Local Quantum Theory (that is the most general formulation of Quantum Field Theory, if we leave out only the unknown scenario of Quantum Gravity) the notion of Statistics can be grounded solely on the local observable quantities (without assuming neither the commutation relations nor even the existence of unobservable charged field operators); one finds that only the well known (para)statistics of Bose/Fermi type are allowed by the key principle of local commutativity of observables. In this frame it was possible to formulate and prove the Spin and Statistics Theorem purely on the basis of First Principles.