共查询到20条相似文献,搜索用时 250 毫秒
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为研究温度对固体推进剂点火燃烧性能的影响,需对实验用燃烧室进行温度控制。为进行优化控制,建立了内置面热源的密闭方腔耦合传热模型,利用FLUENT软件,对流动和耦合传热进行了三维数值仿真。计算采用离散坐标(DO)辐射模型,Boussinesq假设。计算结果表明,在自然对流的密闭方腔内,辐射换热比导热和自然对流换热更具主导地位。腔内中心上升的热流与边壁附近下降的冷流形成自然对流环流,环流的速度较高,而上述两部分中间夹层的流体速度较低。数值仿真反映了实验用燃烧室内温度及流场的分布,为实验数据的准确性提供了理论依据。 相似文献
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温度传感器动态性能改进的软测量方法 总被引:1,自引:0,他引:1
在分析温度传感器工作机理的基础上,采用软测量的思想对改善温度传感器动态特性进行了研究。该方法利用热力学基本理论建立温度传感器软测量模型和理论分析测量模型,说明软测量方法提高温度传感器动态特性的原理及可行性,最后用分析解法对模型进行数值求解,给出数值模拟结果。结果表明:软测量方法能够实现由温度传感器测得的温度推算出被测温度,即提高温度传感器动态响应特性,从而扩大常规温度传感器的使用范围,节约成本。 相似文献
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铜精炼阳极炉氧化过程铜液温度软测量模型及应用 总被引:2,自引:0,他引:2
基于铜精炼阳极炉氧化过程热工机理,建立了铜精炼阳极炉氧化过程铜液温度软测量模型,在铜液温度软测量的算法设计中采用数据预处理、黄金分割法搜索区间以及软测量模型参数校正等技术。实际应用结果表明,铜精炼阳极炉氧化过程铜液温度软测量可以反映氧化过程铜液温度的真实变化,有助于实现铜精炼阳极炉精炼过程铜液温度软控制以及提高铜精炼过程的生产效率和生产质量。 相似文献
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软测量在电石生产中的应用 总被引:1,自引:0,他引:1
针对电石生产中比电阻难于测量的问题,从工艺上对这一关键参数加以分析,提出了采用线性回归分析的方法来建立其软测量模型的方法与步骤,并且在实际中以其为控制目标加以应用,现场的反馈数据表明这种软测量方法在电石生产中是行之有效的。 相似文献
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基于模糊建模的冷凝器污脏软测量 总被引:1,自引:0,他引:1
提出了一种基于模糊建模的冷凝器污脏软测量方法.该方法选取传热端差作为研究对象,应用模糊建模技术分离出冷凝器污脏对端差的影响.在模糊建模中,采用T-S模型描述变工况传热端差,研究了一种相似度判别法则以确定最优模型结构,并采用实数编码的遗传算法同时优化模型前、后件参数,从而获得了规则简化、精度较高的模糊模型.根据此方法,设计了试验系统,并进行了现场试验.试验结果表明:该方法能有效地在线监测冷凝器污脏,并在冷凝器出现堵管或空气漏入量较大时,取得比热阻法、传热系数法更可靠的测量结果. 相似文献
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从生物细胞代谢角度,分析了发酵过程中生物代谢参数的相关性,找出了能够表示生物变量大小的代谢参数,然后将这些参数作为输入变量,建立了菌体细胞浓度软测量的神经网络模型。仿真结果表明,该软测量方法较一般的菌体浓度软测量方法具有更高的准确性和鲁棒性。 相似文献
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铜精炼炉内温度是冶炼过程重要的工艺和控制参数,但难以实现在线连续测量.本文在考虑了炉内高温在线测量需求的基础上,根据炉墙物理结构建立了炉墙非线性瞬态热传导模型,提出采用热电偶测量炉墙内温度以求解热传导反问题间接计算炉内壁温度的解决方案:根据热电偶测温位置将求解域划分为正区域与反区域两部分,引入基于最小方差的局部正交Gram多项式理论对测温信号进行平滑滤波,运用有限元法求解正区域边界热通量,利用直线法高效求解炉内壁温度,实现炉温在线连续测量.具体的实验结果表明,本方法能够克服了热传导反问题不适定性,是一种有效的炉温间接测量方法. 相似文献
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Heat transfer in microchannel devices using DSMC 总被引:4,自引:0,他引:4
The heat transfer characteristics of supersonic flows in microchannels is studied using direct simulation Monte Carlo (DSMC) method. The velocity components and the spatial coordinates of the simulated particles are calculated and recorded by using a variable-hard-sphere (VHS) collision model. The effects of Knudsen number (Kn) on the heat transfer of the microchannel flows are examined. The results show that the magnitude of the temperature jump at the wall increases with increasing Kn. The heat transfer to the isothermal wall is found to increase significantly with Kn. The possible causes for the increase of wall heat transfer are discussed 相似文献
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利用神经网络控制连续浇铸过程中的热传导 总被引:2,自引:0,他引:2
In continuous casting, the cooling-solidification process must be based on the adaptation of heat transfer, which is directly connected to casting conditions such as casting speed, casting temperature, and cooling parameters. Most control schemes are based on the static relation between casting speed and water flow rate in each cooling zone; this constitutes an open loop that does not consider the dynamic surface temperature, which is an important parameter for the final slab quality. In steelmaking, the casting-speed changes affect the global heat transfer. An optimal operation requires an adjustment of the process control variables, i.e., global heat transfer. A learning neural network (NN) allows the identification and the control of a nonlinear heat transfer model in the continuous casting process. A heat transfer model was developed using the dynamic heat balance. A comparison between the experimental open loop results and those of the model simulation is considered. Following adaptation, the model is used for controlling the slab surface temperature in closed loop, using NN technology and PID controllers. The NN identification and control strategy gives a stable temperature closed loop control comparatively to the conventional PID. 相似文献
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Qinglong Meng Yuan Wang Xiuying Yan Zhiqiang Li 《Simulation Modelling Practice and Theory》2009,17(4):730-742
This paper presents a novel modeling approach of coupling transient computational fluid dynamics (CFD) simulation with system identification for control system involving fluid flow and heat transfer. In order to illuminate the feasibility of this method, a fluid flow and heat transfer related process, i.e. a three dimension (3-D) spatio-temporal air temperature distribution and input (inlet air temperature) dependent process in the desert climate chamber, is considered. The distributed parameter models of the chamber temperature are identified using transient CFD simulation results and are then validated against the results obtained from the CFD simulations with high RT2 (more than 0.97) and negative Young’s information criterion (YIC, less than ?11.8). The PI controllers embedded in CFD simulation are then developed based on the models. The performance of the closed-loop systems is also evaluated within the full-scale CFD model. The results show that CFD-based system identification is feasible to model fluid flow and heat transfer related processes. 相似文献
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采用CFD方法,基于剪切应力输运(Shear Stress Transport,SST)湍流模型,求解大长细比卷弧翼火箭弹在超声速情况下的气动力和气动热问题.对火箭弹流场进行数值计算,与实验数据进行对比.采用薄壁模型模拟结构耦合传热,计算在一定海拔和旋转情况下火箭弹的气动加热,并与不旋转的情况进行对比.计算结果表明该数值方法能较好地计算气动力因数和气动热分布.在特定的低转速和海拔情况下的火箭弹温度分布比不旋转的稍微大一点,在旋转情况下的火箭弹尾部截面压力分布不对称,尾部流线更加紊乱;弹头和尾翼前缘温度较高,应当在火箭弹设计中予以考虑. 相似文献
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One of the most important components in micro-fluidic system is the micro-channel which involves complicated flow and transport
process. This study presents micro-scale thermal fluid transport process inside a micro-channel with a height of 37 μm. The
channel can be heated on the bottom wall and is integrated with arrays of pressure and temperature sensors which can be used
to measure and determine the local heat transfer and pressure drop. A more simplified model with modification of Young’s Modulus
from the experimental test is used to design and fabricate the arrays of pressure sensors. Both the pressure sensors and the
channel wall use polymer materials which greatly simplify the fabrication process. In addition, the polymer materials have
a very low thermal conductivity which significantly reduces the heat loss from the channel to the ambient that the local heat
transfer can be accurately measured. The air flow in the micro-channel can readily become compressible even at a very low
Reynolds number condition. Therefore, simultaneous measurement of both the local pressure drop and the temperature on the
heated wall is required to determine the local heat transfer. Comparison of the local heat transfer for a compressible air
flow in micro-channel is made with the theoretical prediction based on incompressible air flow in large-scale channel. The
comparison has clarified many of the conflicting results among different works. 相似文献
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One of the most important components in a microfluidic system is the microchannel which involves complicated flow and transport
process. This work presents microscale thermal fluid transport process inside a microchannel with a height of 37 μm. The channel
can be heated on the bottom wall and is integrated with arrays of pressure and temperature sensors which can be used to measure
and determine the local heat transfer and pressure drop. A more simplified model with modification of Young’s Modulus from
the experimental test is used to design and fabricate the arrays of pressure sensors. Both the pressure sensors and the channel
wall use polymer materials which greatly simplifies the fabrication process. In addition, the polymer materials have a very
low thermal conductivity which significantly reduces the heat loss from the channel to the ambient that the local heat transfer
can be accurately measured. The airflow in the microchannel can readily become compressible even at a very low Reynolds number
condition. Therefore, simultaneous measurement of both the local pressure drop and the temperature on the heated wall are
required to determine the local heat transfer. Comparison of the local heat transfer for a compressible airflow in microchannel
is made with the theoretical prediction based on incompressible airflow in large scale channel. The comparison has clarified
many of the conflicting results among different works. 相似文献
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Sascha Kuhn August Burr Michael Kübler Matthias Deckert Christoph Bleesen 《Microsystem Technologies》2010,16(10):1787-1801
The injection molding of micro-structures is a promising mass-production method for a broad range of materials. However, the
replication quality of these structures depends significantly on the heat flow during the filling stage. In this paper, the
filling and heat transfer of v-groove and random structures below 5 μm is investigated with the help of an AFM (atomic force
microscope) and thermo couples. A numerical model is developed to predict the filling of surface structures during the filling
and packing stage. The model implies the use of simple fully developed flow models taking the power-law material model into
account. This permits investigation into which ways several processing parameters affect the polymer flow in the surface structures.
The mold wall temperature, which has significant effects on the polymer flow, is varied by using a variothermal mold temperature
control system to validate the model proposed. 相似文献