In this article, numerical investigation of the effects of different plasma actuation strengths on the film cooling flow characteristics has been conducted using large eddy simulation （LES）. For this numerical resea...In this article, numerical investigation of the effects of different plasma actuation strengths on the film cooling flow characteristics has been conducted using large eddy simulation （LES）. For this numerical research, the plasma actuator is placed downstream of the trailing edge of the film cooling hole and a phenomenological model is employed to provide the electric field generated by it, resulting in the body forces. Our results show that as the plasma actuation strength grows larger, under the downward effect of the plasma actuation, the jet trajectory near the cooling hole stays closer to the wall and the recirculation region observably reduces in size. Meanwhile, the momentum injection effect of the plasma actuation also actively alters the distributions of the velocity components downstream of the cooling hole. Consequently, the influence of the plasma actuation strength on the Reynolds stress downstream of the cooling hole is remarkable. Furthermore, the plasma actuation weakens the strength of the kidney shaped vortex and prevents the jet from lifting off the wall. Therefore, with the increase of the strength of the plasma actuation, the coolant core stays closer to the wall and tends to split into two distinct regions. So the centerline film cooling efficiency is enhanced, and it is increased by 55% at most when the plasma actuation strength is 10.展开更多
在双碳背景下,综合能源园区(Community-level integrated energy system,CIES)是提升能源利用效率、降低碳排放等多重效益的重要途经。针对当前综合能源园区参与电能量市场与旋转备用市场的研究中,大多忽略了实践中存在的旋转备用市场...在双碳背景下,综合能源园区(Community-level integrated energy system,CIES)是提升能源利用效率、降低碳排放等多重效益的重要途经。针对当前综合能源园区参与电能量市场与旋转备用市场的研究中,大多忽略了实践中存在的旋转备用市场准入资格,且小型运营商难以满足旋转备用市场设立的资格要求问题,提出一种考虑多园区运营商合作竞标以满足备用市场最小功率要求与最短时长要求的策略。首先,构建考虑旋转备用市场准入资格的两阶段资源组合模型;然后,建立包含多种不合格备用资源、以多综合能源园区总运营成本最小为目标函数,并将上述资源组合模型嵌入的经济优化运行模型。最后,通过算例对比分析考虑不同园区的资源组合对系统优化的影响。结果表明,所建立的考虑旋转备用市场准入资格的资源组合模型可以有效降低系统运营成本,验证了所提模式的有效性与经济性。展开更多
目的分析心血管健康与空腹血糖异常的妊娠糖尿病产妇不良妊娠结局的关系。方法选取2019年1月至2020年12月在温岭市妇幼保健院院产检的空腹血糖异常妊娠糖尿病产妇604例,根据母婴不良结局发生情况,分为子痫前期组(n=27)与非子痫前期组(n=...目的分析心血管健康与空腹血糖异常的妊娠糖尿病产妇不良妊娠结局的关系。方法选取2019年1月至2020年12月在温岭市妇幼保健院院产检的空腹血糖异常妊娠糖尿病产妇604例,根据母婴不良结局发生情况,分为子痫前期组(n=27)与非子痫前期组(n=577),计划性剖宫产组(n=535)与非计划性剖宫产组(n=69),巨大儿组(n=61)与非巨大儿组(n=543),以及新生儿低血糖组(n=58)和新生儿低血糖组(n=546),比较各组临床资料和妊娠期心血管健康评分的差异,并采用二元Logistic回归分析心血管健康评分与多项母婴不良结局的关系。结果非子痫前期组的血压、总胆固醇情况以及心血管健康评分均优于子痫前期组,差异有统计学意义(P<0.05);计划行剖宫产组的空腹血糖(fasting plasma glucose,FPG)、体质量指数(body mass index,BMI)、分娩时孕周以及心血管健康评分均优于非计划性剖宫产组,差异有统计学意义(P<0.05);非巨大儿组的FPG、总胆固醇、BMI、体力活动情况以及心血管健康评分均优于巨大儿组,差异有统计学意义(P<0.05);新生儿非低血糖组的FPG、膳食情况以及心血管健康评分均优于新生儿低血糖组,差异有统计学意义(P<0.05)。二元Logistic回归分析结果显示,血压、总胆固醇及心血管健康评分是子痫前期的独立影响因素(P<0.05);FPG、心血管健康评分是非计划性剖宫产的独立影响因素(P<0.05);FPG、总胆固醇、BMI及心血管健康评分是巨大儿的独立影响因素(P<0.05);FPG、心血管健康评分是新生儿低血糖的独立影响因素(P<0.05)。结论空腹血糖异常的妊娠糖尿病产妇心血管健康程度越好,不良妊娠结局的风险就越低,为今后临床干预奠定了基础。展开更多
文摘In this article, numerical investigation of the effects of different plasma actuation strengths on the film cooling flow characteristics has been conducted using large eddy simulation （LES）. For this numerical research, the plasma actuator is placed downstream of the trailing edge of the film cooling hole and a phenomenological model is employed to provide the electric field generated by it, resulting in the body forces. Our results show that as the plasma actuation strength grows larger, under the downward effect of the plasma actuation, the jet trajectory near the cooling hole stays closer to the wall and the recirculation region observably reduces in size. Meanwhile, the momentum injection effect of the plasma actuation also actively alters the distributions of the velocity components downstream of the cooling hole. Consequently, the influence of the plasma actuation strength on the Reynolds stress downstream of the cooling hole is remarkable. Furthermore, the plasma actuation weakens the strength of the kidney shaped vortex and prevents the jet from lifting off the wall. Therefore, with the increase of the strength of the plasma actuation, the coolant core stays closer to the wall and tends to split into two distinct regions. So the centerline film cooling efficiency is enhanced, and it is increased by 55% at most when the plasma actuation strength is 10.
文摘在双碳背景下,综合能源园区(Community-level integrated energy system,CIES)是提升能源利用效率、降低碳排放等多重效益的重要途经。针对当前综合能源园区参与电能量市场与旋转备用市场的研究中,大多忽略了实践中存在的旋转备用市场准入资格,且小型运营商难以满足旋转备用市场设立的资格要求问题,提出一种考虑多园区运营商合作竞标以满足备用市场最小功率要求与最短时长要求的策略。首先,构建考虑旋转备用市场准入资格的两阶段资源组合模型;然后,建立包含多种不合格备用资源、以多综合能源园区总运营成本最小为目标函数,并将上述资源组合模型嵌入的经济优化运行模型。最后,通过算例对比分析考虑不同园区的资源组合对系统优化的影响。结果表明,所建立的考虑旋转备用市场准入资格的资源组合模型可以有效降低系统运营成本,验证了所提模式的有效性与经济性。
文摘目的分析心血管健康与空腹血糖异常的妊娠糖尿病产妇不良妊娠结局的关系。方法选取2019年1月至2020年12月在温岭市妇幼保健院院产检的空腹血糖异常妊娠糖尿病产妇604例,根据母婴不良结局发生情况,分为子痫前期组(n=27)与非子痫前期组(n=577),计划性剖宫产组(n=535)与非计划性剖宫产组(n=69),巨大儿组(n=61)与非巨大儿组(n=543),以及新生儿低血糖组(n=58)和新生儿低血糖组(n=546),比较各组临床资料和妊娠期心血管健康评分的差异,并采用二元Logistic回归分析心血管健康评分与多项母婴不良结局的关系。结果非子痫前期组的血压、总胆固醇情况以及心血管健康评分均优于子痫前期组,差异有统计学意义(P<0.05);计划行剖宫产组的空腹血糖(fasting plasma glucose,FPG)、体质量指数(body mass index,BMI)、分娩时孕周以及心血管健康评分均优于非计划性剖宫产组,差异有统计学意义(P<0.05);非巨大儿组的FPG、总胆固醇、BMI、体力活动情况以及心血管健康评分均优于巨大儿组,差异有统计学意义(P<0.05);新生儿非低血糖组的FPG、膳食情况以及心血管健康评分均优于新生儿低血糖组,差异有统计学意义(P<0.05)。二元Logistic回归分析结果显示,血压、总胆固醇及心血管健康评分是子痫前期的独立影响因素(P<0.05);FPG、心血管健康评分是非计划性剖宫产的独立影响因素(P<0.05);FPG、总胆固醇、BMI及心血管健康评分是巨大儿的独立影响因素(P<0.05);FPG、心血管健康评分是新生儿低血糖的独立影响因素(P<0.05)。结论空腹血糖异常的妊娠糖尿病产妇心血管健康程度越好,不良妊娠结局的风险就越低,为今后临床干预奠定了基础。
