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1.
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   

2.
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   

3.
基于支持向量机的软测量建模方法   总被引:21,自引:1,他引:21  
提出了一种基于支持向量机的软测量方法,并建立了青霉素发酵过程中菌丝浓度的软测量模型,通过实验分析了参数调整和核函数选择对支持向量机建模的影响.利用现场数据建立各种软测量模型可以发现,与其他软测量方法相比,支持向量机方法在理论上优于人工神经网络等其他建模方法.  相似文献   

4.
过程软测量   总被引:11,自引:1,他引:10  
综述了软测量方法的理论框架和五种软测量模型的开发,讨论了软测量在工业中应用的问题,指出了软测量今后的研究方向。  相似文献   

5.
涡流冷壁推力室传热模型分析计算   总被引:1,自引:0,他引:1  
研究发动机燃烧室温度优化控制问题,由于燃烧室温度控制较难,为了预估新型涡流燃烧冷壁火箭发动机的壁面温度,根据发动机内部流动和传热分析,对组合化学平衡、辐射传热和热传导特性,提出了一维传热模型.采用模型对以氢氧为推进剂的涡流燃烧室进行了传热过程和影响因素的仿真分析,获得了稳定状态下的壁面温度,以及燃烧室压力、氧化剂喷注速度、燃烧室长度等参数对壁温的影响关系,仿真结果与实验一致.证明模型为涡流燃烧发动机设计提供了重要工具,对进一步的实验研究有指导意义.  相似文献   

6.
软测量是近年来检测和过程控制领域涌现出的一种新技术,基本原理是利用易测变量来建立模型计算待测变量。针对微波烧结中温度难以测量的问题,在研究微波温度场的基础上,提出了微波烧结材料仿真软测量的理论方法,通过对非微波加热区温度的测量,根据热传导及界面热阻的理论推导出烧结材料的实际温度。并通过试验,用微波炉模拟微波烧结腔体测得温度数据,建立模型。结果证明:根据试验数据建立的模型与假设的指数神经网络模型很吻合,证明了方法的可行性。  相似文献   

7.
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   

8.
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   

9.
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   

10.
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   

11.
在常规连铸二冷配水控制方法的基础上,提出了自适应动态配水控制策略,建立了由基础自动控制、 软测量技术和智能控制技术相结合的二级动态配水控制系统.在控制系统中,建立了基于凝固传热理论的软测量模 型,用于实时预测铸坯表面温度;应用基于自整定神经元的多变量PID 控制算法,实现连铸二冷配水动态单元跟踪 控制,使铸坯表面温度保持在目标值范围内.仿真及应用结果表明了所建模型和控制算法的有效性,控制系统对拉 速扰动具有良好的目标温度跟随性能.  相似文献   

12.
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   

13.
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   

14.
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   

15.
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   

16.
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   

17.
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   

18.
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   

19.
为了获得良好的数值模拟方法预测带横流、旋流冲击射流的流动换热特点,采用SST湍流模型对带横流、旋流冲击射流的流动换热特性进行了三维数值研究,并利用热电偶温度测试装置对冲击靶面局部换热系数分布进行了实验研究和验证.研究结果表明:横流使得靶面换热效果明显降低;横向出流使得靶面换热系数分布均匀化,尤其是在高雷诺数下更为明显.计算结果与实验特征是基本吻合的,所用的数值模拟方法能较为成功的预测带横流、旋流冲击射流的流动换热特性.  相似文献   

20.
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   

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