Influence of Air Flow Rate on Functional Evaluation of Semicircular Canals

Objective To study the influence of unilateral air flow rate change on the result of caloric test.Materials and Methods The unilateral weakness(UW) index was calculated when the air flow rate was set at 6 L /min in both ears(called symmetric stimulation) and again when it was set at 6 L /min in left ear and 3 L /min in the right ear(called asymmetric stimulation).Each individual subject was tested with both symmetrical and asymmetrical stimulations.Paired t test was used to examine the differences between results from symmetrical and asymmetrical stimulations.Result UW index decreased in response to asymmetrical stimulation.Conclusion Unilaterally decreased air flow rate can produce indices suggesting ipsilateral UW,which can be misleading.

Investigation of oil-air two-phase mass flow rate measurement using Venturi and void fraction sensor

Oil-air two-phase flow measurement was investigated with a Venturi and void fraction meters in this work. This paper proposes a new flow rate measurement correlation in which the effect of the velocity ratio between gas and liquid was considered. With the pressure drop across the Venturi and the void fraction that was measured by electrical capacitance tomography apparatus, both mixture flow rate and oil flow rate could be obtained by the correlation. Experiments included bubble-, slug-, wave and annular flow with the void fraction ranging from 15% to 83%, the oil flow rate ranging from 0.97 kg/s to 1.78 kg/s, the gas flow rate ranging up to 0.018 kg/s and quality ranging nearly up to 2.0%. The root-mean-square errors of mixture mass flow rate and that of oil mass flow rate were less than 5%. Furthermore, coefficients of the correlation were modified based on flow regimes, with the results showing reduced root-mean-square errors.

Improvement of uniformity in cultivation environment and crop growth rate by hybrid control of air flow devices

A complete control type plant factory has high efficiency in terms of cultivation area by constructing vertical multiple layered cultivation beds.However,it has a problem of irregular crop growth due to temperature deviation at upper and lower beds and increases in energy consumption by a prolonged cultivation period.In this work,air flow rate inside a facility was improved by a hybrid control of air flow devices like air conditioning and air circulation fan with an established wireless sensor network to minimize temperature deviations between upper and lower beds and to promote crop growth.The performance of proposed system was verified with an experimental environment or Case A wherein air conditioning device was operated without a control algorithm and Case B wherein air conditioning and circulation fans were alternatively operated based on the hybrid control algorithm.After planting leafy vegetables under each experimental condition,crops were cultivated for 21 days.As a result,Case B wherein AC(air conditioning) and ACF(air-circulation fan) were alternatively operated based on the hybrid control algorithm showed that fresh mass,number of leaves,and leaf length for the crops grown were increased by 40.6%,41.1%,and 11.1%,respectively,compared to Case A.

Relationship between Formation Water Rate,Equivalent Penetration Rate and Volume Flow Rate of Air in Air Drilling

Formation water invasion is the most troublesome problem associated with air drilling. However, it is not economical to apply mist drilling when only a small amount of water flows into wellbore from formation during air drilling. Formation water could be circulated out of the wellbore through increasing the gas injection rate. In this paper, the Angel model was modified by introducing Nikurade friction factor for the flow in coarse open holes and translating formation water rate into equivalent penetration rate. Thus the distribution of annular pressure and the relationship between minimum air injection rate and formation water rate were obtained. Real data verification indicated that the modified model is more accurate than the Angel model and can provide useful information for air drilling.

Effect of Air Injector on the Performance of an Air-lift for Conveying River Sand

An air-lift has been more recently applied in the dredging, deep-seated beach placer mining and underground mining engineering. However, the influence and mechanism of various parameters on the air-lift performance are not quite clear, especially the influence of flow pattern on lifting efficiency. Focusing on the problems mentioned above, the key part of the air-lift （namely, the air injector） was proposed aimed to reduce friction loss in the inner pipe according to improving flow field performance, thus increase the lifting efficiency. The study of relative factors of the performance of an air-lift is performed and the river sand is used as simulation of underground ore bed. The total lifting height of the experimental system is 3 m, the water flux, mass flow of solid particles, concentration of particles and lifting efficiency are measured under the same submergence ratios by changing the air injector, which is divided into nine specifications of air injection in this research. The experimental results indicate that the optimal air flow rate corresponding to excellent performance of the air-lift can be obtained in the range of 35-40 m3/h. The air injection method has a great effect on the performance of the air-lift, the air injector with three nozzles is better than that in the case of one or two nozzles. Further more, the air injection angle and arrangement of air injection pipes also have great effect on the performance of an air-lift. The proposed research results have guiding significance for engineering application.

滤筒除尘器喷吹孔孔径的优化

【目的】为控制各个喷吹管气流量的均匀性,对喷吹管上的喷吹孔径进行优化,提高滤筒除尘器清灰效果。【方法】自制高压脉冲喷吹气流量测量装置对现有喷吹管气流量进行测定,采用光纤传感分析仪测试除尘器滤筒各部分的侧壁压力峰值,分析各滤筒清灰效果不均匀的原因;以滤筒各部位侧壁压力峰值作为清灰均匀性效果评估指标,优化喷吹孔径。【结果】优化前4个喷吹孔径均为19 mm,喷吹孔的气流量依次为13.69、 14.78、 16.03、 16.93 L,对应4个滤筒上、中、下部侧壁压力峰值的最小值分别为最大值的37%、 26%、 20%,气流量均匀度标准差为1.41;优化后4个喷吹孔径分别为23、 20、 18、 17 mm,喷吹气流量依次为14.05、 15.08、 15.87、 16.13 L,对应4个滤筒上、中、下部测壁压力峰值的最小值为最大值的56%、 56%、 53%,气流量均匀度标准差降为0.93。【结论】优化后的喷吹管气流量均匀化程度提高,可实现滤筒除尘器的均匀清灰。

羊肚菌室内栽培关键技术研究

目前我国羊肚菌栽培基本都在室外进行,对环境和气候依赖性强,种植风险大。开展可控条件下的羊肚菌室内栽培研究,对羊肚菌产业发展具有裨益。本研究对比不同栽培土壤、不同外源营养袋配方、不同土壤含水量及不同空气流速的栽培效果,得到羊肚菌室内筐式栽培的部分关键技术:采用稻田土12.5 kg+腐殖木屑200 g栽培效果明显优于常规田间土壤;发菌期土壤含水量在24%~27%,其菌丝培养、污染控制及产量表现较好;外源营养袋配方采用小麦63%、麸皮15%、木屑10%、谷壳6%、玉米粉4%、碳酸钙1%、石灰1%,在羊肚菌菌丝培养、营养利用和产量上表现较优;出菇期室内空气流速对子实体发育影响明显,不宜超过0.8 m/s。

气冷冷凝相变脱白法系统计算研究

根据气冷冷凝相变脱白系统设计的需要,开发了排放气体温度、湿度的计算程序,在此基础上研究了冷空气温度、湿度和风量对脱白效果的影响,结果显示:气冷冷凝相变脱白法除雾存在临界风量线,这条线由冷空气温度、湿度和风量共同决定;冷凝相变脱白法比混风脱白法和混合冷凝脱白法效果好。

夏热冬暖地区办公建筑空调系统节能优化研究

随着社会经济的高速发展,办公建筑的数量及能耗日趋增加,为了缓解能源紧缺现状,对既有办公建筑的节能改造成为节约能耗、降低碳排放的重要手段之一。对于夏热冬暖地区,其办公建筑能耗主要为空调系统制冷,本文基于深圳市某办公建筑的原始空调系统,提出两种基于空调系统主要设备的节能优化方案,即磁悬浮机组+变频冷冻水系统、变流量机组+变频变流量系统。通过Trnsys软件对提出的2种优化方案进行对比分析。结果表明,对冷水机组进行设备改换和采用变频技术能在一定程度上降低空调系统能耗,系统的COP有较大的提升。

基于CFD的滚筒搅拌器的冷却模拟研究

以滚筒搅拌器为研究对象,通过CFD软件模拟仿真,通过稳态模拟考察冷却空气流量对冷却效果的影响情况,通过正交模拟实验考察进口颗粒温度、空气总流量以及内壁冷却空气的比例三种因素对冷却效果的影响情况。分析结果表明,冷却空气总流量大于等于50m^(3)/h时,设备就可以完成50℃以下的冷却目标;颗粒温度、空气流量是影响设备冷却效果的最主要因素;冷却时间大于50s后,物料就可以达到冷却平衡。基于该分析结果,对滚筒搅拌器工作的工艺参数进行优化,同时也为设备的结构设计改进提供思路,提高了设备的工作效率。

压力补偿型艉轴密封设计及空气流量特性分析

为某半潜船模型设计一种压力补偿型艉轴密封系统。该密封系统基于空气压力、润滑介质压力实时联动算法,能够根据外部海水压力的变化实现密封内外压差平衡,达到密封的目的。同时,该密封系统可应用于40 m水深作业工况,并具备泄漏回收功能,具有绿色环保特征。利用MATLAB/Simulink搭建该系统的参数设计仿真平台,分别研究轻载与重载下压缩空气的流量特性。研究结果表明:该系统轻载时压缩空气流量为0.0141kg/s,重载时为0.025 0 kg/s;瞬态时存在波动,但稳态时运行平稳,抗干扰性强,密封性能可靠。

多品种种子干燥技术分析与应用

当前多品种种子干燥技术可满足不同品种及小批量种子的繁育需求,该研究旨在探讨分析多品种种子模块化干燥单元的能耗及其内部干燥介质的物理参数。基于多品种种子模块化干燥单元内部种子质量、干燥风温及干燥速度等因素,分析计算其热源及风机的相关参数。结果表明,多品种种子模块化干燥单元的电磁热风炉功率5 kW,风机流量412~859 m^(3)/h,全压507~310 Pa。研究结果以期为多品种种子干燥技术的后续发展提供技术参考及理论借鉴。

热压作用下新风系统水力工况分析方法研究

热压作用导致通过竖直立管送风的空调新风系统水力失调且并联管路阻力不平衡,无法计算管网阻抗及进行水力工况分析,针对该问题提出了适用于热压作用下的新风系统水力工况分析方法。该方法将整体管网看作并联的各末端通风支管虚拟闭合环路,求解压阻平衡方程组,拟合了各闭合环路与管网的特性曲线方程,确定了虚拟闭合环路阻抗,实现了热压作用下管网流体流动及流量分配规律的描述。计算中考虑了管网流量与摩擦阻力系数、局部阻力系数的耦合关系。以某办公楼新风系统为例,利用环路阻抗方法对热压作用下管网的水力工况进行了分析,其计算结果与方程组迭代计算结果相吻合,表明了所提方法的准确性。

挖金湾煤业瓦斯治理技术应用研究

针对挖金湾煤业井下通风风量紧张,瓦斯涌出量急剧提升的现象,采用分源动态预测的方法对挖金湾煤业井下瓦斯涌出量进行了预测分析,通过对瓦斯压力、含量以及通风阻力等指标的测定,了解井下瓦斯状况,找出工作面瓦斯主要来源,并对井下瓦斯涌出量进行预测分析。通过制定瓦斯抽放及井下通风技术方案,提升了瓦斯抽采时间与浓度,提高瓦斯抽采率为73%,保证工作面回风流瓦斯浓度在0.4%以下,回采面上隅角与高位孔处浓度保持在4%~12%,符合煤矿井下安全高效生产要求。

大流量亚微米颗粒物气溶胶精准分离器设计

亚微米颗粒物气溶胶分离器作为目前研究的热点之一,是实现颗粒物浓度高精度检测的先决条件。但当前的颗粒物气溶胶分离器仍存在较多问题,例如小流量时测量距离近,大流量时分离不精准等。该文设计出一种新型大流量亚微米颗粒物气溶胶精准分离器,该分离器可实现远监测点的亚微米颗粒物的大流量富集以及精准分离。依据人造龙卷风抽吸原理以及Marple理论进行模型的初步设计并对其进行数值分析、数值模拟,采用SIMPLE算法对压强-速度耦合求解。文章所述的颗粒物气溶胶分离器平衡了工作流量和切割粒径两者间的矛盾,并对结构进行了分析优化,最终该新型分离器在700 L/min及以上的大流量工况下,实现了对粒径为0.1μm的颗粒物精准分离,极大地提高了分离器的性能。

直射式气动雾化喷嘴对燃烧室性能的影响

为了深入分析燃油喷嘴对燃气轮机燃烧室性能的影响,针对燃气轮机燃烧室中的直射式气动雾化喷嘴开展了数值模拟,获得了气流流量、燃油流量和气液比对雾化性能的影响规律,喷嘴的雾化性能参数包括雾化粒径和雾化锥角。结果表明:气液比和气流流量对该型喷嘴的雾化性能有显著影响,燃油流量对雾化性能的影响较小;气液两相间相对速度是影响该型喷嘴雾化性能的决定因素,相对速度增大有利于减小雾化粒径,并增大雾化锥角;气流流量和气液比的增大均有利于雾化粒径的减小,燃油流量的增加将使雾化粒径增大;增大气流流量、气液比和减小燃油流量均可使雾化锥角增大;该型喷嘴的雾化锥角变化范围为30.12°~41.24°,雾化粒径变化范围为131.46~186.52μm。喷嘴可实现在较小的雾化锥角变化范围内获得较宽的雾化粒径变化,以此匹配燃气轮机燃烧室不同工作状态,具有较高的实用价值。

工艺条件对厨余垃圾生物干化效果的影响

为了研究各工艺条件(调理剂类型、调理剂添加比例、通风速率)对厨余垃圾生物干化效果的影响,为厨余垃圾生物干化工程应用提供指导。分别选取3种调理剂、4个调理剂添加比例、4个通风速率,分析生物干化过程中物料的温度、含水率、挥发性固体(volatile solid,VS)降解率变化,评价其生物干化效果。结果表明:添加木屑作为调理剂可以缩短升温期、延长高温期。加入木屑的处理组物料含水率降幅为31.97%,比只有厨余垃圾的对照组高18.57%。添加15%木屑的处理组生物干化效果最佳,温度最高可达63.8℃,含水率降低了32.36%。不同的通风速率影响物料的温度和水分的散失,通风速率为0.4 L/(kg·min)时有机物消耗最少,水分去除效果最佳。实际厨余垃圾生物干化工业应用可以考虑添加15%木屑做为调理剂,通风速率设为0.4 L/(kg·min)。

1000 MW燃煤机组旋流燃烧器及燃尽风风门差异化调节特性

对冲燃烧煤粉锅炉因二次风系统结构复杂、布置紧凑,难以对燃烧器及燃尽风内、外二次风进风量进行准确监测,热态运行时风门调节盲目,普遍存在炉膛宽度方向两侧燃烧严重缺风问题。为充分提升对冲燃烧煤粉锅炉炉膛两侧旋流燃烧器及燃尽风进风量,获得理想风门开度组合,以某电厂1000 MW燃煤机组为研究对象,对二次风系统进行完整建模及流动数值模拟,系统性定量研究旋流燃烧器及燃尽风内、外二次风门差异化调节特性。结果表明:燃烧器及燃尽风风门均一全开初始状态下,沿炉膛宽度方向二次风量呈中间大、两边小的分配特性,与对冲燃烧锅炉实际运行炉膛两侧缺风现象相符;燃烧器/燃尽风内、外二次风开度两侧向中间依次为100%/100%、60%/50%、50%/40%、40%/40%时,炉膛宽度方向上,燃烧器及燃尽风进风量均呈两侧向中间递减的理想状态,与均一全开初始状态相比,炉膛两侧进风量增大8.3个百分点,按初始侧边氧量1.80%计,侧边氧量将显著提升1.15个百分点,同时,燃尽风占总二次风量的比例略微提升0.6个百分点,基本不影响炉膛高度方向上的分级燃烧程度。

ISO 6级洁净室换气次数确定方法的实验研究

非单向流洁净室设计时,由于事先无法准确获得室内发尘量资料,一般按洁净度要求利用相关设计规范确定换气次数取值范围,但所选用的换气次数在各种因素的影响下,实际使用时是否能满足洁净度要求,是否会过大而造成能耗浪费。以一典型顶送侧回的ISO 6级非单向流洁净室为研究对象,利用正交实验方法,获得对室内洁净度影响较大的4个因素影响程度排序:室内发尘量、换气次数、送风口尺寸、尘源高度。在此基础上,在送风结构与房间污染源位置固定的洁净室内,进行不同换气次数下室内发尘量对室内浓度变化的特性实验。通过实验结果获得不同换气次数、发尘量时的颗粒物浓度计算拟合式,以此确定了ISO 6级下选用换气次数的室内最大允许发尘量,即按规范选用50~60次/h换气次数时室内最大允许发尘量为7.4×10^(4)~8.9×10^(4)pc/(m^(3)·min)。同样,还可确定在不同发尘量时需要的最小换气次数,比如室内发尘量为4.0×10^(4)pc/(m^(3)·min)时,此时ISO 6级洁净室只需nmin=27次/h。因此,按洁净度确定非单向流洁净室换气次数的同时考虑室内发尘量的大小,可以在满足室内洁净度要求的同时节约能源。