Steady air injection flow control for increasing the surge margin of radial flow compressor

Steady air injection upstream of the leading edge was used to increase the surge margin of a centrifugal compressor.To reveal the mechanism,steady numerical simulations were performed on a high pressure ratio centrifugal compressor rotor operated with a rotor tip speed of 586 m/s.Eight different injection yaw angle with four different injection mass flow was performed to determine the configuration that provide the best results for the compression system studied in this work.The injection angle,α,was fifteen degree and the injectors were placed at short distance（ten percent of the inlet tip radius upstream of the compressor face） to achieve maximum control over the leading edge flow by varying individual injection parameters.The results show that at design speed（n=50 000 r/min） with injection flow rate more than 2% of the main flow rate and yaw angle between 20° and 30°,the mass flow rate at stall decreases for approximately 8%.But with higher injection rate,other compressor parameters were affected such as compressor efficiency and compressor total pressure ratio.

Enhancing Aerodynamic Performances of Highly Loaded Compressor Cascades via Air Injection

This article experimentally studies the effects of air injection near the blade trailing edge on flow separation and losses in a highly loaded linear compressor cascade. Aerodynamic parameters of eight cascades with different air injection slot configura- tions are measured by using a five-hole probe at the cascade outlets. Ink-trace flow visualization is performed to obtain the flow details around the air injection slots. The static pressure distribution is clarified with pressure taps on the endwalls. The...

高温工况下两相补气对空调压缩机热力性能的影响研究

在夏季超高温条件下,室外局部环境温度可达到50℃以上。过高的冷凝温度意味着压缩机排气压力较高、压比较大,同时压缩机散热困难,导致压缩机的排气温度超过120℃,压缩机内润滑油面临碳化风险,严重地影响了压缩机的可靠性。此外,在夏季超高温条件下,空调的制冷量快速衰减,制冷效果不尽人意。对于上述问题,在现有补气增焓技术的基础上提出两相补气,以解决夏季超高温工况下压缩机排气温度过高、制冷量衰减较大的问题。

乳制品行业压缩空气系统无油化改造案例浅析

阐述催化式除油系统在内蒙古蒙牛圣牧高科奶业有限公司喷油螺杆压缩机系统改造项目中的应用,结合催化燃烧式除油原理,以及改造后实际应用效果,针对乳制品及相关食品行业对无油空气等级的严格要求,提出一种将含油压缩空气系统无油化改造思路和方法,并针对无油螺杆压缩机实际运行环境提出优化建议。

大功率水冷螺杆空压机换热分析与研究

功率为315 kW及以上的螺杆空压机在运行时会释放出大量的热量,为保证螺杆空压机的稳定运行,根据热力学第一定律及对流换热公式,通过对大功率水冷螺杆空压机热量分布及传热过程进行分析与研究,给出了螺杆压缩机组其冷却系统的设计计算方法:包括空压机的循环喷油量,油冷却器换热面积,后冷却器换热面积,冷却水进出水温度,冷却水塔换热参数,冷却水泵流量与扬程等参数进行了分析与计算,能够为大功率水冷螺杆空压机冷却系统的设计提供了较好的指导意义。

Influence of Endwall Air Injection with Discrete Holes on Corner Separation of a Compressor Cascade

The aim of this study is to reveal the influence mechanism of endwall air injection with distributed holes on the corner separation of a highly loaded compressor cascade,so as to promote the application of injection in aero-engines.Single-hole and double-hole endwall injection schemes featuring different axial locations,pitchwise locations,injection mass rates and injection directions,were designed and investigated.Results showed that the corner separation was eliminated by endwall injection;the optimal single-hole injection scheme achieved an endwall loss coefficient reduction of 29.7%,with injection coefficient as low as 0.48%.The optimal axial location of single-hole endwall injection was at 82%axial chord,being the center of corner separation.However,as injection hole was located at upstream of it,endwall injection resulted in severer corner separation.The mid-span flow field was deteriorated after endwall injection,which was due to 3D flow effects,i.e.,AVDR(axial velocity density ratio)effect and low-momentum fluid spanwise migration effect.The optimal injection was achieved at low injection angle and from close to the suction surface on pitchwise.Double-hole injection exhibited inferior performance compared with single-hole,which was due to the interaction of the two injection streams and mixing of injection streams with the bulk stream.

水润滑单螺杆空气压缩机性能影响因素的试验研究

为了深入研究水润滑单螺杆空气压缩机性能的影响因素,设计制造了一台水润滑单螺杆空气压缩机,并搭建了测试试验台,通过试验研究了不同转速、排气压力和喷水流量对水润滑单螺杆压缩机性能的影响.结果表明,增加转速可以减小泄漏量,提高压缩机的性能.其余工况不变,只增大喷水流量时,可以提高压缩机的水气比,增强水气之间的换热和压缩机的密封效果,进而提高水润滑单螺杆空气压缩机的各项性能.如转速为3000 r/min、排气压力为0.50 MPa时,喷水流量由50 L/min提高至80 L/min,压缩机的容积效率提高5.15%,绝热效率提高2%,比功率降低0.26 kW/(m3·min^(-1)).由于水的黏度远小于润滑油,因此为了保证压缩机的性能,水气比要高于同工况下的油气比.在额定转速3000 r/min下,排气压力为0.50~0.65 MPa时,建议的水气比范围为2.94%~3.48%.

喷油参数对双螺杆空压机性能的影响

为研究喷油参数对双螺杆空压机工作性能的影响,并为优化和提高该类型空压机的整体性能提供参考,建立了喷油双螺杆空压机数学模型,研究喷油量、喷油温度等对空压机性能的影响,并通过模拟结果与实验结果的比较,验证了模型的准确性。结果表明:双螺杆空压机存在一个最优的喷油量,可以使空压机达到最佳的绝热效率和比功率,随着转速由3000 r·min^(-1)升高至4400 r·min^(-1),最优喷油量呈现下降的趋势,随着背压由0.7 MPa提高至1.0 MPa,最优喷油量呈现升高的趋势。另外,喷油温度的升高使得双螺杆空压机的绝热效率下降、比功率上升,从而导致空压机性能恶化,因此在保证排气温度的同时,应尽量选择低的喷油温度。同时,喷油参数对泄漏与耗功的影响显著,随着喷油温度由303.15 K升高至323.15 K,各个泄漏通道泄漏量呈现上升的趋势,摩擦损耗呈现下降的趋势;随着喷油量由0.5 m 3·h^(-1)增加至1.5 m 3·h^(-1),各个泄漏通道泄漏量呈现下降的趋势,摩擦损耗呈现上升的趋势。研究工作可为喷油双螺杆空压机的性能优化提供有益的参考。

Experimental Investigations of Micro Air Injection to Control Rotating Stall

Steady discrete micro air injection at the tip region in front of the first compressor rotor has been proved to be an effective method to delay the inception of rotating stall in a low speed axial compressor. Considering the practical application a new type of micro injector was designed and described in this paper, which was imbedded in the casing and could be moved along the chord. In order to verify its feasibility to other cases, such as high subsonic axial compressor or centrifugal compressor, some other cases have been studied. Experimental results of the same low speed axial compressor showed that the new injector could possess many other advantages besides successfully stabilizing the compressor. Experiments performed on a high subsonic axial compressor confirmed the effectiveness of micro air injection when the relative velocity at the blade tip is high subsonic. Meanwhile in order to explore its feasibility in centrifugal compressor, a similar micro injector was designed and tested on a low speed centrifugal compressor with vaned diffuser. The injected mass flow was a bit larger than that used in axial compressors and the results showed micro injection could also delay the onset of rotating stall in the centrifugal compressor.

煤矿综放工作面注氮灭火的工程应用

为进一步提升煤矿工作面生产的安全性,以15107工作面为例,对于其自燃煤层容易与氧气氧化反应导致火灾发生的问题,在对注氮灭火工艺特点和有效性分析的基础上,根据现场情况及注氮灭火工艺提出了输氮管路、制氮装置、空气压缩机的选型;通过实践表明,注氮工艺可明显起到防火灾的目的。

钢铁企业喷油螺杆空压机的余热利用设计

介绍了钢铁企业喷油螺杆空压机余热利用的设计,喷油螺杆空压机在钢铁企业有着广泛的应用,对喷油螺杆空压机进行有效的余热利用可以帮助企业节能降耗,创造利润,减少温室气体排放。通过工程实例,讨论了钢铁企业喷油螺杆空压机的余热利用设计以及需要注意的问题.

叶尖喷气影响低速离心压气机特性的数值分析

本文采用数值模拟方法研究了进口叶尖喷气对低速离心压气机稳定工作范围的影响。计算讨论了机匣开缝和机匣安装喷嘴两种喷气方案,通过改变喷气量、喷气角、气流偏角以及喷嘴的周向布置研究不同喷气形式对压气机特性的影响。结果显示两种喷气方案均可起到拓宽压气机稳定工作范围的作用,各参数间存在最优组合使喷气的扩稳效果最佳。

扩压叶栅中采用带切向孔叶片的研究

数值模拟了低速条件下大转角压气机叶栅中采用带切向孔叶片对叶栅性能的影响。结果表明,与常规不开孔的叶栅相比,采用带切向孔叶片的压气机叶栅通流能力提高1.3%左右,叶栅总损失降低17%左右。气动性能的改善一方面来源于切向孔附近叶片负荷的降低,横向二次流动减弱;另一方面,穿过切向孔在吸力面表面形成的射流增加了吸力面角区内低能流体的能量,提高了其抗分离能力。针对本文算例,从提高做功能力和减小损失的角度看,切向孔应布置在80%轴向弦长以前为好。

喷气对低速轴流压气机转子叶顶区域流动的影响

本文采用数值模拟方法研究了近失速工况动叶顶部前缘附近喷气对低速轴流压气机孤立转子叶顶区域流动的影响。受喷射气流的影响,叶顶泄漏流进行自发非定常波动的动态平衡被破坏,建立起新的周期性非定常波动;喷气不仅改变了叶顶泄漏流的起始触发位置,还影响到其形成后的形态和运行轨迹;且喷气后叶顶附近区域损失减小。

补气转子式压缩机变工况制热性能的分析

将中间补气技术应用于单缸滚动转子式压缩机上,通过实验研究的方法分析R410A喷气增焓系统在变工况、变频及变补气压力条件下制热性能的动态变化规律。实验结果表明:当环境温度Tod=-7℃时,随压缩机频率f及中间补气压力pinj的增加,系统的制热量和功率逐渐增加,而系统COPh逐渐减小;在环境温度(Tod)为-15~7℃区间变工况运行时,系统补气质量比在高、低温工况时与补气压力的关系截然相反,其主要由补气比容ninj、补气压差pinj-pwc、补气时间dt之间的相互关系决定,与单级压缩系统相比,补气系统制热量、功率随环境温度的升高而逐渐增大,平均增幅分别为24.52%、24.39%,补气系统COPh在低温、低补气压力时最高提升10.7%,而在高温状态单级压缩系统性能更具有节能优势。

跨音速轴流压气机叶顶间隙泄漏流对微喷气的非定常响应机制和扩稳效果研究

本文将叶顶微喷气方法应用于NASA Rotor37跨音速轴流压气机转子,在近失速工况,利用数值模拟方法研究了不同喷气量时叶顶间隙泄漏流对微喷气的非定常响应机理和叶顶微喷气的扩稳效果。结果表明,喷气使得叶顶区域的叶表压力随喷嘴与叶片相对位置的变化沿弦向发生波动,抑制了叶顶泄漏流的自激非定常波动,使叶顶泄漏流轨迹沿叶片吸力面向下游移动,实现了提高压气机性能和稳定性的目的。采用喷射气流的无量纲总动量可关联亚音速和跨音速轴流压气机不同喷气方案的扩稳效果,该无量纲总动量与来流总动量和喷射气流高度成反比,而与叶高和喷射气流总动量成正比。

小型低温空气源热泵用转子和涡旋压缩机对比

空气源热泵是一种利用高位能使能量从低位热源空气流向高位热源的节能装置。阐述了小型低环境温度空气源热泵(输入功率在1～4 kW,工作环境温度可达-20℃)的概念和用能效率评定方式。介绍了适用于小型低环境温度空气源热泵的两种全封闭压缩机:转子压缩机和涡旋压缩机。对比了两类压缩机的压缩原理;通过技术分析和产品调研,对两类压缩机的基本特性、喷气增焓和喷液增焓技术、变频技术和适用工况等方面进行了分析,并对其变压比特性进行阐述;对其制造工艺进行比较。得出了两种压缩机的适用性对比。

单缸补气转子式压缩机在热泵系统中制热性能

利用中间补气技术将单缸滚动转子式压缩机应用于空气源热泵系统中,系统地研究以R410A为冷媒的热泵系统在变频、变补气压力工况下制热性能的变化规律。实验结果表明:中间补气系统的制热量及系统功率均随着压缩机频率f、中间补气压力pinj的增加呈上升趋势,同频率下系统功率则以线性方式增长,而系统制热量随着补气压力及频率的增大,其相对增长率逐渐减小。因此COPh在低频时存在最佳补气压力,而在高频时无极值点;与单级压缩系统相比,在800~1200 k Pa、50~80 Hz范围内,中间补气系统的制热量、功率、COPh最大提升分别为27.55%、30.75%、7.1%。随着频率及补气压力的增加,系统COPh下降,因此中间补气技术应与合理的控制策略相结合,可使中间补气系统达到节能高效的目的。

喷气增焓涡旋低温空气源热泵制热性能的分析

空气源热泵制热技术已广泛应用于华北地区的减煤代煤供暖等清洁供暖工程,随着低温空气源热泵制热技术的发展,把这一清洁替代能源供暖技术推广应用于东北部分地区,已具备技术可行性。本文对喷气增焓涡旋低温空气源热泵的制热性能进行了热力学分析和试验对比检测,结果显示在模拟室外气温为-25℃、相对湿度为86%时,10 hp喷气增焓涡旋空气源热泵的制热性能系数为1.38,可满足东北部分地区的冬季供暖需求。通过对辽宁省绥中县工程实例的运行检测,验证了该热泵供暖技术应用于东北部分地区的技术可行性。但若要使其具备较好的经济可行性,还需搭配其他经济性节能技术参与节省运行费用,以及政府财政补贴等扶持政策,共同收回初投资。

涡旋压缩机气阀复杂脱模机构及模具结构优化设计

针对结构复杂塑件-涡旋压缩机气阀自动化注射成型生产的需要,设计了一种1模2腔三板式点浇口注射模。模具中,针对塑件4处局部特征的构造特点,相应地,优化设计了4种脱模机构来实施自动脱模,分别为4次脱模复合机构、2次脱模复合机构、斜导柱滑块机构、定模弯销抽芯机构。4次脱模复合机构中,首先利用外部油缸机构完成中央内孔的第1次抽芯脱模,而后再利用延时滑块机构完成口部和端面的第2次、第3次抽芯脱模,最后,通过油缸齿条机构完成内螺纹的第4次旋转抽芯脱模。2次脱模复合机构中,先利用斜导柱滑块机构完成中央内孔的第1次抽芯脱模,再利用油缸齿条机构完成内螺纹的第2次旋转抽芯脱模。斜导柱滑块机构、定模弯销抽芯机构采用通用型机构。通过对4次脱模复合机构、2次脱模复合机构的油缸齿条驱动机构的优化设计,优化了模具整体结构尺寸,有效降低了注塑机的使用成本。