STUDY ON EXPERIMENTS FOR SUPPRESSING WINGTIP VORTICES WITH PLASMA

该文对利用dbd等离子体注入能量抑制翼尖涡进行了风洞试验研究。通过采用PIV粒子成像测速技术测量了三种不同结构的等离子体激励器影响下的后掠翼下游的尾涡流场,并结合矩形机翼在等离子作用前后的气动力变化,来判断等离子体抑制翼尖涡的效果。试验结果表明:在机翼翼梢的上下表面处布置等离子体激励器,通过等离子体产生的定向诱导气流形成诱导涡对流场注入能量,可以有效地延缓翼梢上翼面流动分离,抑制翼尖涡,增加升力,提高升阻比。在翼尖处流动分离较小时,等离子体抑制翼尖涡强度的效果明显;在大攻角下仍具有一定的作用;其效果与等离子体发生器的结构有关。因此,通过优化等离子体激励器结构,选择合适的等离子体激励器在翼梢表面的安放位置,可以更好地提高抑制翼尖涡的效果。The wind tunnel experiment on suppressing wingtip vortices(WTV) through adding energy with DBD plasma has been conducted in the paper.The WTV flow field of a swept wing has been visualized by PIV and the aerodynamic forces of a rectangular wing have been measured,in the condition of using three different kinds of plasma actuators respectively.The results show that the WTV may be suppressed and the separation on the upper wingtip surface may be delayed because the energy of the vortex induced by the plasma(VIP) is added into the flow field,which increases the lift and the ratio of lift to drag at a small angle of attack(AOA) effectively.Even at large AOA,the effect of plasma still appears.The effects are related to the structures of the plasma actuators.It can be obtain better results to suppress the WTV through optimizing the design of the plasma actuators and choosing the appropriate placement to install the actuators on wingtip surface.福建省自然科学基金项目(A1010014

基于等离子体合成射流的飞翼布局模型主动流动控制风洞实验研究

为探究等离子体合成射流对三维模型的流动控制效果和机理,在中等展弦比飞翼布局模型前缘布置等离子体合成射流激励器开展低速风洞实验研究。通过六分量天平测力,考察沿弦向、展向不同分布位置的等离子体合成射流对飞翼模型气动力和气动力矩的作用;采用PIV(Particle Image Velocimetry,粒子图像测速)测量模型表面流场分布,研究等离子体合成射流流动控制机理。结果表明:在飞翼模型单侧布置等离子体合成射流,能够有效改善其气动特性,并能产生附加的滚转力矩,滚转力矩系数变化量最高达到0.009;在飞翼模型左右弦布置等离子体合成射流,能显著增强飞翼模型横向稳定性,滚转力矩系数波动范围减小66.7%。沿弦向,等离子体合成射流位置离前缘越近,控制效果越好,距前缘0mm的激励器控制效果最好;沿展向,布置的等离子体合成射流越多,对模型的升力特性改善作用越明显,布置方式以均布为优。在失速迎角前后,等离子体合成射流的流动控制机理不同:在小迎角下,等离子体合成射流在前缘起到了使转捩提前的作用;在失速迎角附近,则加速了分离区的流动、减小了分离区厚度。国家自然科学基金项目(51707169)中航工业创新基金产学研项目(cxy2013XD28)福建自然科学基金项目(2019J01042)厦门大学校长基金项目(20720170057

AERODYNAMIC MOMENTS CONTROL OF WING MODEL USING PLASMA JET

为考察火花放电等离子体射流控制机翼气动力矩的效果,在NACA0021平直机翼模型上安装火花放电等离子体射流发生器,通过改变射流发生器安装位置、射流角度及加载电参数,研究其控制机翼模型气动力矩的性能及机理。在NACA0021机翼模型近前缘处,布置2个火花放电等离子体射流发生器,采用气动力测量技术,在来流风速为20 m/s时测得,攻角-4°~10°时,滚转力矩系数最大减小了0.0024,攻角为12°~16°时,滚转力矩系数最大增加了0.0021;偏航力矩系数最大减小了0.00097。实验研究结果表明:等离子体射流可改变机翼模型横航向气动力矩,并可通过改变射流角度和加载电压频率调节等离子体射流控制横向气动力矩的效果。To investigate the control effect of Spark Discharge Plasma Jets(SPJs) on the aerodynamic moments of a wing, SPJ generators were used for active flow control experimental study on an NACA0021 straight wing model. The location of SPJ generators along the chord of the airfoil, the jet flow direction relative to the chord, and the driving voltage parameters were changed to research the control effect and mechanism of SPJ generators on the aerodynamic moments of a wing model. The aerodynamic moments were measured with a six-component balance at a wind speed of 20 m/s. Two SPJ generators, arranged near the leading edge, reduced the rolling moment coefficient by a maximum of 0.0024 for angles of attack-4°~10°, but increased the rolling moment coefficient by a maximum of 0.0021 for angles of attack 12°~16°. The yaw moment coefficient was reduced by a maximum of 0.00097. The results show that aerodynamic moments control of wings can be realized using SPJs. The control effect of SPJs on the aerodynamic moments is changeable by adjusting the driving voltage frequency and the jet flow direction relative to the chord.航空科学基金项目(20141368007);; 福建省自然科学基金项目(2010J01014

Experimental Study on Accelerating the Gas Flow Induced by Planar Coil Electromagnetic Coupling Surface DBD Gas Discharge

为了提高典型沿面dbd平板激励器诱导气流速度,通过实验研究了典型dbd平板激励器表面的磁场分布,提出了在dbd平板激励器的上、下电极之间夹进平面线圈,运用电磁耦合原理增强等离子体激励器放电效果,从而加速dbd等离子体诱导气流的方法。探究了不同结构参数的电感线圈产生的电磁耦合作用对大气压下平板式dbd等离子体激励器放电加强的效果,以及夹进平面线圈后加载电源的电压和频率对dbd放电的影响,并利用粒子图像测速技术测量了电磁耦合作用下典型dbd等离子体诱导气流流场,考察了其中电磁耦合对加速诱导气流的作用。实验结果表明,运用电磁耦合作用可在一定程度上增强等离子体激励器的放电效果,一些电感线圈产生的电磁耦合作用可显著改善dbd等离子体诱导气流的连续性和加厚流场区域。To accelerate the flow induced by typical surface DBD actuator, we studied the magnetic distribution on the surface of a typical DBD actuator qualitatively through experiments.We proposed a method that inductance coils between the upper electrode and the lower electrode were installed to enhance the discharge and increase the flow speed due to the electromagnetic coupling applied to the plasma actuator.Inductance coils with different structure parameters which could create various electromagnetic coupling impacts were used to improve the DBD plasma discharge.Furthermore, we measured the induced flow charts of DBD plasma actuators with electromagnetic coupling using the particle image velocimetry to study the electromagnetic coupling impact on increasing the flow speed induced by DBD plasma.The results show that, by applying electromagnetic coupling to the typical DBD plasma actuator, its discharge can be improved and the airflow induced by the plasma can be accelerated by some kinds of inductance coils, improving the induced flow in both continuity and thickness.福建省自然科学基金(2010J01014)~

嫌気性ルーメンツボカビ菌 Piromyces sp. P1 によるセルロース分解とメタン菌の存在(農学部門)

メタン菌存否の環境下でPiromyces sp. P1を培養しセルロース分解率を測定した。その結果, セルロース分解率はメタン菌非存在下では44.3%であったが, メタン菌の存在によって分解率は65.5%に増大した。これは水素生成がメタン菌の存在によってスムーズに行われたためと考えられた。そこで, Piromyces sp. P1の水素生成を阻害するために, 水素あるいは一酸化炭素(ヒドロゲナーゼ阻害剤)を添加し分解率を調べた。気相中50%の水素を添加したところ, 分解率は34.5%に低下した。一酸化炭素の添加による阻害はさらに著しく16.6%まで低下した。これらの結果から, メタン菌が水素を消費し水素分圧を低下させることが, Piromyces sp. P1のセルロース分解を促進する要因であると思われた。Cellulose digestion by Piromyces sp. P1,a ruminal anaerobic fungus, was determined under the existence of methanogen. The digestibility without methanogen was 44.3%, but the existence of methanogen improved the digestibility to 65.5%. This may be caused by the ease of hydrogen production under the existence of methanogen. Hydrogen and carbon monoxide were added to inhibit hydrogen production by Piromyces sp. P1. Addition of 50% hydrogen depressed the digestibility to 34.5%, and that of carbon monoxide much more depressed it to 16.6%. These results suggest that the reduction of hydrogen partial pressure by methanogen may improve the cellulose deigestion by Piromyces sp. P1

Investigation on new-style plasma active flow controllers and its induced flow field

利用空气中阻挡介质沿面放电等离子体诱导定向气流的特性,创造性地设计多种可用于流动控制的等离子体主动流动控制器;有目的地布置电极,主动组织等离子体诱导的定向气流,形成所需的气体流动结构;对其进行流动显示试验,并采用PIV技术对各新型等离子体流动控制器所形成的流场进行测量。研究结果表明,合理地设计等离子体流动控制器,可以得到所需的流动结构,用于流动控制。本文的研究成果为主动流动控制提供了一类新型的无源流动控制器。The kinds of new-style plasma flow controllers have been designed to control flow actively according to the behavior of the directional air flow induced by DBD(Dielectric Barrier Discharge) plasma in still air.The desired flow structures have been obtained by organizing the directional flow induced by DBD plasma through arranging electrodes in the controllers purposefully.The flow fields induced by the new-style plasma active flow controllers have been investigated visibly and measured by PIV.The experiment shows that the required structure of the induced flow can be realized through designing new-style plasma flow controllers reasonably to control flow actively.The research results provide a novel flow controller without flow source for active flow control.福建省自然科学基金(A0410001;A1010014

可追溯宁夏大米土壤中硒的本底分布情况及其含量评价[J]

为了满足人们对健康的追求,研究从宁夏稻米种植区土壤中微量元素硒含量的本底状况及含量评价展开。以宁夏回族自治区粮食作物耕作区的基本农田为调查采样的目标区域,通过原子分光光度法对土壤中微量元素硒进行检测分析,比较了全土壤中平均含量、不同行政区土壤以及不同土壤类型中微量元素硒含量的差别。结果表明:所采集的土壤样品中,不同行政区土壤样品中硒含量差别不大,而不同土壤类型中硒含量有差别且西部土壤含硒量较高,其中局部地区达到中硒土壤上限

宁夏可追溯大米土壤重金属(铅、砷、汞、镉)的本底分布情况及含量评价[J]

为了评价宁夏地区主要粮食作物(大米)种植区重金属含量的本底状况和污染程度。研究以宁夏回族自治区粮食作物耕作区的基本农田为调查采样的目标区域,通过原子分光光度法对土壤中的重金属铅、砷、汞、镉进行检测分析,比较了全土壤、不同行政区土壤以及不同地貌单元及土壤类型中重金属含量的差别,并且计算了不同来源土壤的污染指数。结果表明:实验所采集的不同行政区土壤中重金属含量存在差别,而不同地貌单元及土壤类型中重金属含量并无差别,且所有土壤样本的重金属本底值均达到一级土壤质量的标准要求。通过计算污染指数得出,研究所采集土壤区域农田环境均达到清洁级水平

基于GIMMS与SPOT vegetation的中亚物候变化趋势及对比[J]

植被物候是反映生态系统受全球气候变化影响的重要证据。作为生态与水资源系统最为脆弱的地区之一,中亚干旱区植被物候对气候变化的响应情况是当前的全球环境变化研究热点。文章以GIMMS和SPOT vegetation数据为基础,在TIMESAT物候信息提取软件的支持下,以动态阈值法提取了1982─2006年和1999─2012年中亚地区植被物候空间信息。结合Mann-Kendall趋势分析方法,对中亚地区2个时期的植被开始期,停止期和生长季长度的3种典型物候参数的历史变化情况和空间分布进行识别;同时,通过二维散点图和最小二乘一维线性回归的统计分析方法,开展了对1999─2006年8年重叠期期间GIMM..