旋流燃烧室内气体-颗粒两相湍流流动的数值模拟

综合应用代数Reynolds应力模型和流体相脉动速度大小和方向均具有随机性的颗粒相随机轨道模型,对旋流燃烧室内有直流射流与旋转射流相互作用的气-固两相湍流流动进行了数值模拟.得到的气相轴向与切向速度和轴向脉动速度均方根值分布以及颗粒相轴向总质量流通量和轴向与切向速度分布与实验基本相符合,并比对气相湍流采用k-ε模型的相应计算结果有较明显的改进.     

简化的Solomon热解模型和旋流煤粉燃烧NO生成的数值模拟

提出一种简化的Solomon热解模型, 用于模拟煤粉燃烧NO生成数值模拟中HCN的释放.用纯双流体模型、k-ε-k_p两相湍流模型、EBU-Arrhenius燃烧模型、六热流辐射模型、双方程热解模型、简化的Solomon热解模型以及NO生成湍流反应二阶矩代数模型对旋流煤粉燃烧器内两相流动、煤粉燃烧、HCN释放以及NO生成进行了数值模拟.模拟结果与文献中实验结果的对比表明,基于简化Solomon热解模型的HCN释放模型预报结果比基于双方程热解模型的HCN释放模型预报结果好.     

辊道窑烧嘴喷射角度对窑内湍流气流影响的研究

应用k -ε两方程湍流模型 ,对辊道窑烧成带的湍流旋流流动进行了理论分析 ,并用计算流体力学软件Fluent进行数值模拟 ,研究了烧嘴的喷射角度对烧成带内的湍流旋流流动的影响及其对制品烧成的作用     

各向异性k-ε湍流模型在Rushton桨搅拌槽三维流场整体数值模拟中的应用

根据搅拌槽内的流动呈各向异性的特点 ,引入适用于强旋转流场的各向异性k -ε湍流模型 ,用改进的内外迭代法对有挡板的Rushton桨搅拌槽进行了整体数值模拟 .利用文献中对搅拌槽内流场测定结果 ,给出了适用于Rushton桨搅拌槽的各向异性湍流黏度系数值 .模拟计算得到了搅拌槽内的流场分布和脉动速度分布 ,并同标准k -ε湍流模型计算结果及文献数据进行比较 .结果表明 ,各向异性k -ε湍流模型能成功反映Reynolds应力、湍流动能等湍流特征量 ,明显优于标准k -ε湍流模型 .     

催化裂化沉降器新型高效旋流快分器内气固两相流动

用CFX软件对催化裂化沉降器新型旋流快分器的气相流场进行了三维模拟,湍流模型采用雷诺应力输运方程模型.计算结果与用五孔探针测试的气相流场实验结果吻合很好.采用离散轨道模型对该旋流快分器内颗粒的运动情况进行了计算,并由此估算了旋流快分器的分级效率和总分离效率.模拟结果表明：该新型旋流头可消除现有旋流头喷出口附近的短路流,更有利于提高旋流快分器的效率.两种结构形式的旋流快分器分离效率的计算对比说明：在旋流头处加入一个内构件,是很有价值的改进.     

燃料环缝进口的丙烷-空气旋流扩散燃烧的LES-EBU和RANS-SOM模拟的比较

用Smagorinsky-Lilly亚网格尺度湍流模型和EBU亚网格尺度湍流燃烧模型,对燃料环缝进口的丙烷-空气旋流湍流燃烧进行了大涡模拟（LES）,并且用二阶矩（SOM）统观湍流燃烧模型进行了RANS模拟,将模拟所得统计平均的热态三个方向速度,湍流度,温度,丙烷、氧和CO₂浓度分布和详细的实验数据对比.结果表明,LES-EBU大涡模拟的统计结果不如RANS-SOM模拟结果.因此,EBU亚网格尺度湍流燃烧模型有待改进.RANS-SOM模型可以进一步在预报工程中的旋流扩散燃烧中应用.     

催化裂化沉降器旋流快分系统内气相流场的数值模拟与分析

为进一步提高催化裂化沉降器旋流快分系统的分离效率,首先对系统内气相流场进行了研究和分析.采用CFX5软件和应力输运方程模型（DSM）对其气相流场进行了三维数值模拟.将计算结果与用五孔探针测试的流场实验结果对比发现,计算结果与实验结果吻合较好,证明了应力输运方程模型适合用于旋流快分系统内三维流场的数值模拟.模拟结果表明：旋流快分系统内的流场为三维湍流场,在旋流头喷出口附近区域存在多个纵向旋涡,存在短路流现象,这是导致分离效率不易提高的主要原因.旋流快分头的S值和倾斜角对气流切向速度都有一定的影响,应优化确定.加入汽提气后,对旋流快分系统内的流场影响不大,但对气体的快速引出有利.     

旋流塔板上的两相流场

在直径300mm塔内,用激光多普勒测速仪对旋流塔板上的流场进行了实验研究,探明其主要特征,进一步证实了过去对不同用途板型的设计思想.采用两方程k-ε湍流模型,应用有限差分法,对塔板上的气流场进行了数值模拟,计算结果与实验值符合良好.     

基于RSM和LES湍流模型的旋流分离器流场数值模拟

采用三维结构网格,分别用雷诺应力模型和大涡模拟对旋流分离器内流场进行数值模拟,得到不同截面上速度、湍流强度和涡量的分布规律,并将速度模拟结果与LDV测试结果进行对比,结果表明,大涡模拟结果更接近LDV测量值,更适合旋流分离器内流场的数值模拟。     

重力势能驱动旋流冶金反应器流动特性数值模拟

重力势能驱动的冶金反应器是一种仅利用钢液本身的重力势能作为动力驱动产生旋流,借用旋流的力量对钢液进行搅拌,无需外加动力和物质的炉外精炼设备.应用CFD软件Fluent对重力势能驱动的旋流冶金反应器进行三维数值模拟,并对几何模型的建立、网格生成技术、湍流模型、离散方法、欠松弛因子及边界条件等问题进行了探讨.模拟结果表明,该冶金反应器可以产生可观的旋流,在漏斗型反应器的壁面加不同形式的叶片会产生不同强度的旋流,在已知的3种叶片形式中,前弯型叶片产生的旋流效果最佳.数值模拟所获得的轴截面上的速度分布规律与水模型实验研究结果基本吻合,验证了数值模拟的可行性,同时也为进一步研究重力势能驱动旋流冶金反应器的结构优化和冶金性能预测提供参考.     

鼓泡床内气液两相流动的二阶矩模型与代数应力模型的模拟比较

A full second-order moment(FSM) model and an algebraic stress (ASM) two-phase turbulence model are proposed and applied to predict turbulent bubble-liquid flows in a 2D rectangular bubble column.Predication gives the bubble and liquid velocities,bubble volume fraction,bubble and liquid Reynolds stresses and bubble-liquid velocity correlation.For predicted two-phase velocities and bubble volume fraction the is only silight difference between these two models,and the simulation results using both two models are in good agreement with the particle image velocimetry(PIV) measurements.Although the predicted two-phase Reynolds stresses using the FSM are in somewhat better agreement with the PIV measurements than those predicted using the ASM,the Reynolds stresses predicted using both two models are in general agreement with the experiments.Therefore,it is suggested to use the ASM two-phase turbulence model in engineering application for saving the computation time.     

Modellierung und Simulation von Strömungen und biologischen Reaktionen innerhalb eines Belebtschlammbeckens

With the aim to increase the efficiency of the aeration tanks of municipal wastewater treatment plants, the implementation of a biological model system (ASM1) into the CFD code ANSYS CFX® is presented for modeling a full‐scale aeration tank and verified with experimental data. Taking into account the biological processes, hydrodynamics and gas‐liquid mass transfer, simulations were performed and compared to experimental concentration profiles for ammonium and nitrate. The assumptions made are explained in detail. While the simulated ammonium concentration profile is in good agreement with the measured values, deviations occur for the nitrate profile. However, the CFD simulations exceed the prediction accuracy of conventional 0D simulation software.     

Use of activate sludge model no. 3 and Bio-P module for simulating five-stage step-feed enhanced biological phosphorous removal process

The ASM3 with EAWAG Bio-P Module (ASM3+P) was used for simulating a five-stage step-feed Enhanced Biological Phosphorous Removal (fsEBPR) process and its applicability was compared with the ASM2d. The fsEBPR process was predicted to achieve effective nitrogen and phosphorus removal from the wastewater even with low C/N and C/P ratios without additional carbon sources. Application of the ASM3+P on this configuration will be an ample chance for expanding the new models in the activated sludge process. Sensitivity analysis and parameter estimation were conducted with the ASM2d and the ASM3+P prior to model application so that calibration of the models could focus only on the sensitive parameters. The ASM2d was less successful for predicting the process behavior. Moreover, the ASM2d required 6 times more computation time than that for the AMS3+P due to its decay-regeneration model structure. To confirm the applicability of parameters determined from the pilot-scale reactor operating results, those were tested on the field data without further correction. Only the ASM3+P successfully predicted nitrogen and phosphate variations in the full-scale plants. Overall examination of simulation results using the pilot and full-scale data has led to the conclusion that the ASM3+P is better than the ASM2d for simulating fsEBPR processes.     

Potentiometric and Thermodynamic Studies of 2-Acrylamidosulfamethazine and Its Metal Complexes in Monomeric and Polymeric Forms

2-Acrylamidosulfamethazine (ASM) was synthesized and characterized by elemental analyses and IR spectroscopy. Proton-monomeric ligand dissociation and metal-monomeric ligand stability constants of ASM with some metal ions were determined potentiometrically in 0.1 M KCl and 40% (v/v) ethanol–water mixture. In the presence of 2,2-azobisisobutyronitrile as an initiator, the dissociation and stability constants of ASM were determined in polymeric form (PASM). The influence of temperature on the dissociation of ASM and the stability constants of their complexes in monomeric and polymeric forms were precisely studied. The pK^H value of PASM was found to be higher than ASM, which indicates that the vinyl group in the monomeric form decreases the electron density on nitrogen and hence reduces the N–H bond strength. The stability constants of the metal complexes in polymeric form are higher than those of the monomeric form. This reveals that the ligand in a polymeric form may be considered as a better complexing agent.     

Polymer Complexes XXXV. Potentiometric and Thermodynamic Studies of Monomeric and Polymeric Complexes Containing 2-Acrylamidosulphamethoxazole

Summary 2-Acrylamidosulphamethoxazole (ASM) was synthesized and characterized by elemental analyses, IR and ¹H NMR spectra. Proton-monomeric ligand dissociation and metal-monomeric ligand stability constants of ASM with some metal ions were determined potentiometrically in 0.1 M KCl and 40 % (vh) ethanol-water mixture. In the presence of 2,2-azobisisobutyronitrile as initiator, the dissociation and stability constants of ASM were determined in polymeric form (PASM). The influence of temperature on the dissociation of ASM and the stability constants of their complexes in monomeric and polymeric forms were precisely studied. The pK₂^H value of PASM was found to be higher than ASM, this means that the vinyl group in the monomeric form decreases the electron density and hence reduces the N-H bond strength. The stability constants of the metal complexes in polymeric form are higher than those of the monomeric form. This reveals that the ligand in a polymeric form is considered as a better complexing agent.     

ASM1在污水生物处理中的应用与研究

采用以IWA的活性污泥数学模型1号模型(ASM1)为平台开发的污水处理仿真程序模拟城市生活污水处理工艺,其出水结果与实测数值的误差小于10%,说明活性污泥数学模型能较好地反映污水处理厂的实际运行状况,基于ASM1的软件可用于模拟污水处理、预测出水水质及作辅助工艺设计的工具。     

A systematic model calibration methodology based on multiple errors minimization method for the optimal parameter estimation of ASM1

A one-step model calibration methodology of the activated sludge model no. 1 (ASM1) of a full-scale wastewater treatment plant (WWTP) is proposed. First, the key parameters among all parameters of the ASM1 model are selected by sensitivity analysis based on the effluent quality index. Second, multiple response surface methodology (MRSM) is conducted to find the optimal parameter values of the ASM1 model. Lastly, an MRSM analysis is conducted in order to determine the optimal parameter values. This study was conducted in order to develop a new systematic model calibration methodology that can greatly help the modeler to find the optimal solution by selecting the key parameters and optimizing the parameters. In two case studies of simple activated sludge process and a full-scale plant, the experimental results indicated that the calibrated models can improve the prediction quality of the ASM model and the efficiency of the modeling.     

Influence of weathering process on the flotation response of coal

The floatability of a Spanish coal from a seam (Adolfa) which is simultaneously surface mined (ASM) and underground mined (AUM) has been studied. The mineral composition of AUM and ASM coal samples, as well as changes in both mineral and organic constituents due to chemical weathering, were characterized by X-ray diffraction, i.r. and Mössbauer spectroscopies and X-ray fluorescence spectrometry. The effect of pH and surface charge on the floatability of AUM and ASM samples was investigated. The formation of humic substances in the surface of ASM coal and the presence of Fe(III) species in its mineral matter, both a consequence of weathering, together with the high content of mineral impurities (especially aluminosilicates) provide an explanation for the flotation behaviour of this coal. Basic pHs that led to humic acids dissolution and to iron(III) hydroxide precipitate desorption from the surface improved ASM coal floatability up to values similar to those obtained with unoxidized AUM coal. The formation of humic acids-mineral impurities complexes at basic pHs renders clay particles hydrophobic. As a consequence, the improvement of ASM coal floatability at pHs higher than neutral was accompanied by a low ash rejection. Mineral impurities had a large influence on the surface charge of ASM coal.