共查询到19条相似文献,搜索用时 343 毫秒
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跨音速轴流压气机级三维粘性流场全工况数值模拟 总被引:4,自引:0,他引:4
采用一种快速求解三维粘性流场的计算方法求解跨音速轴流压气机级内部流场及全工况特性。该方法以LU-SGS-GE隐式格式和MUSCL TVD迎风格式为基础,结合壁面函数方法和简单的混合长度湍流模型,对三维可压缩雷诺平均Navie-Stokes方程进行求解。叶列间参数的传递采用混合平面方法并应用了微机网络并行计算技术。计算得到了NASA 37号低展弦比、跨音速轴流压气机级70%设计转速下的全工况性能曲线,并重点分析了其中一些典型工况下的内部流场。计算与实验结果的对比表明此方法能快速得到三维粘性流场的流动特性且计算精度较高,可用来模拟跨音速轴流压气机级内的全工况三维粘性流动。 相似文献
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为了研究等离子体点燃超音速混合气流的过程,设计并验证了超音速燃烧室的三维计算模型,计算出了燃烧室等离子体点火时的流场参数和化学反应规律,分析了等离子体点火对燃烧室内燃烧的影响。计算结果表明:高温等离子体射流的滞止作用通过增加混合气在燃烧室内的停留时间提高了点火效率; 等离子体点火时燃烧区域的压力扩散比较充分,内部为压力相对平衡的低速流动; 高温等离子体射流高速射向混合气流时产生的速度矢量偏移扩大了点火面积,从而使点火效率得到提高; 氢气、空气燃烧的燃烧产物主要是水,燃烧区域局部温度主要受局部放热反应的影响。 相似文献
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应用改进的3维化学反应流程序,对基于RADICL装置、以氮气为稀释气体的化学氧碘激光喷管流动做了数值模拟。给出了达到合适副气流穿深的主副气流匹配条件,考虑了提高水汽流量、改变主副气流总温对增益系数的影响,比较了与以氦气为稀释气体的不同特点。结果发现:氮气作为稀释气体条件下,混合气体的流速低,静压大,在亚声速区驻留时间长,碘分子离解快,使得增益系数峰值增大,且下降快。模拟结果提示:改变喷管结构,将副气流喷孔下移,增益分布得到了改善。 相似文献
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了对短周期风洞实验中,实验段建立起周期性稳定流动的时间进行估算,以便在实验中把握测量时间,保证测量数据的有效性和推确性,本文采用显式时间推进方法求解二维Euler方程对短周期风洞中二维涡轮叶栅的非定常流动进行了模拟。除预测建立起周期性稳定流动过程中的流场特征和达到周期性稳定流动所需的时间外,对叶片的升力等冲击载荷在建立起周期性稳定流动过程中的变化也进行了估算,为三维涡轮部件瞬态实验方案的规划和实验设备的研制提供帮助 相似文献
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中国散裂中子源需要建设一台多功能反射谱仪中子探测器,满足在10年运行期间内,50%(@2A)以上的探测效率、好于2 mm的二维位置分辨、200 mm×200 mm的灵敏面积、3倍的n/γ分辨能力及良好的二维成像性能.基于此要求,探测器因此采用基于高气压~3He气体的多丝正比室,并以满足反射谱仪的探测效率、位置分辨、长期稳定工作和n/y分辨能力为目标进行探测器的设计.本文经过模拟和实验计算得出:以9 mm厚的铝合金入射窗、铝丝密封的高气压腔体和6 bar~3He+2.5 bar C_3H_8的工作气体的设计,可满足探测器对2 A中子10年运行期间内54%以上的探测效率要求;探测器对中子的位置分辨可达到1.4 mm左右;设计的气体净化系统,拥有2 L/min的气流速度可有效去除探测器内的负电性杂质气体,气体循环净化后可提高探测器约27%的气体增益,保证探测器长期稳定的运行;通过对~(252)Cf中子源的能谱测量和成像测量,得出探测器的n/γ分辨能力在5倍以上和均匀的成像结果.研制的探测器满足反射谱仪需求,并已在中国散裂中子源反射谱仪靶站就位联调. 相似文献
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针对THz频段微电真空器件波导壁面材料电导率及加工粗糙度引发损耗的模拟需求,研制了有限电导率模块,并将其添加进三维全电磁粒子模拟大规模并行程序NEPTUNE3D。介绍了有限电导率的时域有限差分显格式及时谐场近似解方法,针对上述方法的优缺点,提出了基于扩散方程隐格式的有限电导率模块算法,该算法具备无条件稳定、普适性好的优点。利用矩波导常见电磁波模传输损耗算例,测试了自编的有限电导率模块,测试结果与理论值及同类商业电磁软件计算结果进行了比对,验证了模块的可靠性。利用添加有限电导率的三维全电磁粒子模拟程序NEPTUNE3D,模拟了材料电导率以及表面粗糙度对0.22 THz折叠波导行波管性能的影响,模拟结果表明,材料电导率及表面粗糙度会显著降低器件输出功率和增益水平。综合色散关系、耦合阻抗、衰减常数等因素,给出了器件结构参数设计建议,并指出:通过增加电子束流、注入信号功率以及慢波结构周期数目等方式可一定程度上提高器件输出功率水平。 相似文献
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We propose a computational method for generating sequential kinoforms of real-existing full-color threedimensional (3D) objects and realizing high-quality 3D imaging.The depth map and color information are obtained using non-contact full-color 3D measurement system based on binocular vision.The obtained full-color 3D data are decomposed into multiple slices with RGB channels.Sequential kinoforms of each channel are calculated and reconstructed using a Fresnel-diffraction-based algorithm called the dynamicpseudorandom-phase tomographic computer holography (DPP-TCH).Color dispersion introduced by different wavelengths is well compensated by zero-padding operation in the red and green channels of object slices.Numerical reconstruction results show that the speckle noise and color-dispersion are well suppressed and that high-quality full-color holographic 3D imaging is feasible.The method is useful for improving the 3D image quality in holographic displays with pixelated phase-type spatial light modulators (SLMs). 相似文献
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The characteristics of an amine-based all-gas-phase iodine laser (AGIL) are studied. At constant flow rates of the chemical species, the small-signal gain and laser output power are measured at three different positions in the flow reactor. It is clarified that the positive gain exceeding the threshold (2.3×10?3%/cm) is maintained over a region more than 80 mm long along the flow. The highest small-signal gain of 7.8×10?3%/cm and laser output power of 50 mW are observed at 170 mm downstream from the mixing point of HI and H. Numerical simulations suggest that the long positive-gain region is attributable to the following characteristics of the present apparatus: inefficient mixing and inefficient H2 dissociation. It is confirmed experimentally and numerically that these limitations are beneficial for extending the positive-gain region to the downstream; however, the optimum HI flow rate is limited a small value and results in a much lower gain than the theoretical limit. In order to achieve a higher gain, fast mixing and efficient H2 dissociation must be simultaneously achieved so as to increase the optimum HI flow rate. Numerical simulation results suggest that a positive gain of 5.4×10?2%/cm, a 7-times higher gain than that indicated by the present experimental results, should be obtained with the same NCl3 flow rate. 相似文献
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A Numerical Study of Characteristic Slow-Transient Behavior of a Compressible 2D Gas-Liquid Two-Fluid Model 下载免费PDF全文
H.A. Friis S. Evje & T. Flå tten 《advances in applied mathematics and mechanics.》2009,1(2):166-200
The purpose of this paper is to gain some insight into the characteristic
behavior of a general compressible two-fluid gas-liquid model in 2D by using numerical
computations. Main focus is on mass transport phenomena. Relatively few
numerical results in higher dimensions can be found in the literature for this two-fluid model, in particular, for cases where mass transport dynamics are essential.
We focus on natural extensions to 2D of known 1D benchmark test cases, like water
faucet and gas-liquid separation, previously employed by many researchers for the
purpose of testing various numerical schemes. For the numerical investigations,
the WIMF discretization method introduced in [SIAM J. Sci. Comput. 26 (2005),
1449] is applied, in combination with a standard dimensional splitting approach.
Highly complicated flow patterns are observed reflecting the balance between acceleration
forces, gravity, interfacial forces, and pressure gradients. An essential
ingredient in these results is the appearance of single-phase regions in combination
with mixture regions (dispersed flow). Solutions are calculated and shown from
early times until a steady state is reached. Grid refinement studies are included to
demonstrate that the obtained solutions are not grid-sensitive. 相似文献
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In this paper we have presented a semi-automatic method for segmenting and counting the Fluorescence In Situ Hybridization (FISH) signals per cell nucleus in a 3D tissue image. The number of FISH signals indicate the gain (trisomy) or loss (monosomy) of certain base-sequences in deoxyribonucleic acid (DNA). The quantitative evaluation of the loss or gain in DNA is necessary in qualitative diagnostic molecular pathology. Multispectral volumetric images are obtained using the Confocal Microscope. Each consists of a red channel depicting the 3D morphology of the tissue and green channel containing the FISH signals. The red channel tissue image is segmented first to determine the membership of the FISH signal to a particular nuclei. Various segmentation methods starting from simple local thresholding to volume growing and active volumes are used for segmentation. A brief comparative study of the visual signal count by pathologist and our automatic count is also presented. 相似文献