单孔氧枪喷头射流流场的仿真研究

借助商业软件CFX4．4对单孔氧枪Laval喷管内及喷管外的射流场进行数值模拟，分析了不同滞止压力下喷管外的轴对称射流流场的分布情况，并验证了k-ε湍流模型的适用性。结果表明，300K环境温度下，射流的径向横截面面积受轴向至喷口的距离影响较大，而在不同滞止压力下（0．596—0．996MPa）射流沿纵向扩展变化不大；在相同滞止压力下，随环境温度增加，射流径向扩展明显加大。关键词单孔氧枪Laval喷管轴对称湍流射流数值模拟     

Laval喷管内流动特征的数值模拟

借助商业软件CFX4．4，对laval喷管内的流场进行数值模拟，从理论上分析了不同滞止压力下管内的流动状态以及激波的产生情况，并验证了k-ε湍流模型的适用性。     

轴对称湍流射流流场的数值模拟

借助商业软件 CFX4.4,对 Laval 喷管外的射流流场进行数值模拟,分析讨论了不同滞止压力、环境温度对湍流射流轴中心线上流场的影响,对比以往模拟结果和实际现场氧枪操作曲线验证了是k-ε湍流模型在描述湍流射流流场方面的适用性.     

基于解析法的氧枪喷管设计及模拟

氧枪喷管由收缩和扩张两段组成,其型线的合理与否直接关系到其流动性能的好坏,因此合理设计方法的选择对喷管设计有着重要的意义。基于解析法设计超音速喷管的收缩段和扩张段,运用CFD数值模拟技术对其进行计算。分析了基于解析法的氧枪喷管的射流特性,得出其内部压力降低,速度增加,压力损失小,且各段流体能够稳定的过渡,出口马赫数满足设计要求。     

超低碳Nb-V-Ti微合金钢热变形行为的研究

在热模拟实验的基础上，分析了变形条件及微合金元素Nb(0．018％～0．056％)、V(0．01％-0．02％)、Ti(0．01％-0．02％)对0．06％-0．08％C实验钢的热变形行为的影响。在Sellas-Tartat方程的基础上，建立了应力-应变曲线数学模型：动态回复模型σ(e)=σ0 (σp—σ0)[1-exp(-3．23ε/εs)]^0.5，式中：σp-峰值应力，σ0-初始应力，ε-变形应变，σs-加工硬化与回复进入稳态的临界应变；动态再结晶模型σ=σ(e)-(σp-σss){1-exp[-2．363(ε-εc)εc^0.3425)^2]}，式中：σss-动态再结晶进入稳态时的应力，εc-动态再结晶临界应变。利用该模型对0．07％C-0．018％Nb实验钢工业轧制时轧制压力进行了预测，其结果与实测值吻合良好。     

曲线壁型氧枪超音速射流数值模拟研究

转炉氧枪的超音速射流影响转炉金属熔池的供氧、造渣等重要功能。基于foelsh方法设计了一套扩张段为曲线壁型的拉瓦尔管,结合Standard k-ε湍流模型,建立可压缩氧气射流的二维轴对称计算流体动力学(computational fluid dynamics, CFD)模型,对比研究了设计和非设计工况下直线壁型、曲线壁型拉瓦尔管的射流特性。结果表明,曲线壁型拉瓦尔管在喷管出口处的速度提高0.42%～1.35%,可以获得更大的速度增加冲击动能;在出口处曲线壁型喷管的动压较直线壁型喷管提高0.56%,且随着操作压力的提高,曲线壁型喷管的动压衰减更慢;在出口处曲线壁型喷管的静压降低5.4%～8.2%,可降低在出口处形成非完全膨胀波的可能性;曲线壁型喷管内速度矢量更加平行,使得射流拥有更大的冲击动能,搅拌熔池以达到供氧和造渣功能。     

烧结环冷机液密封数值仿真研究

基于Fluent软件,采用标准k-ε湍流模型和VOF多相流模型对环冷机液密封内气液两相流动过程进行了数值模拟研究。运用该模型研究了进口风速、出口压力、水槽液位、初始状态等因素对密封液面的影响,再通过正交实验对4个因素的影响力大小进行了综合分析。研究结果表明,初始状态影响最大,进口风速次之,水槽液位及出口压力影响最小,并得到以减小液密封液面波动为目标的最优运行参数组合:进口风速15m/s,出口压力3300Pa,水槽液位0.5m,初始波高0.02m。模型计算结果与现场测试相比,误差在5%以内,验证模型的正确性,研究结果可用于液密封设计。     

喷射成形雾化器结构对流场的影响

采用美国商用流体力学软件(CFD)模拟了喷射成形雾化腔内气体流动状态,分析了四种不同雾化器喷管结构的流场特点。结果表明:在一定的压力和尺寸条件下,汇聚喷管结构的高速射流区域比汇聚发散结构喷管大,对气体加速作用较好;导流管末端气流速度影响抽吸气体流率,从而影响引流效果;和汇聚发散结构相比汇聚结构喷管更适合用于双层雾化器引流结构。     

完全膨胀的目标设计改进喷砂枪喷管

为改变普通喷砂枪效率低下只适用于处理小型工件的现状,运用CFD方法系统计算了Laval喷管和同口径普通收缩喷管的流场,提出并论证了以完全膨胀状态气流为目标的Laval喷管设计观点。以提高喷气速度和超声速气流长度为有效途径提高喷砂枪效率。     

浸入式水口倾角对宽幅连铸结晶器内流动行为的影响

浸入式水口出口角度影响射流的动能损失,进而影响结晶器内的流动行为.建立了比例为1 ∶ 4的水模型,在模型拉速为0.425 m/min、水口浸入深度为40 mm的条件下,借助粒子图像测速技术研究了浸入式水口出口倾角为0°和+5°对宽幅连铸结晶器内流动行为的影响.结果表明,0°和+5°水口条件下,射流在模型内的流动方式有很...     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.     

Quality of life of relatives of mental patients

Usage of quality of life of psychiatric patients' relatives as the parameter of estimation of the quality of psychiatric care is considered. By means of standard questionnaire elaborated by the authors as well as by means of both individual and group conversations the quality of life was analyzed in 40 relatives which lived together with psychiatric patients. Different spheres of their life and difficulties (financial, social-psychologic, production) were examined in families with such patients. The defects of psychiatric care that had direct influence on the quality of life of the psychiatric patients' relatives are outlined.