柜式空调器室内机风阻的试验与计算研究

通过柜式空调器室内机KFR-70L两种不同进气状态下的整机风阻试验,拟合得出了一个计算整机风阻的公式,并用另一台柜式空调器室内机KF-60L的整机风阻试验数据对计算公式进行了检验和修正,公式可为类似柜机风阻的估算提供参考.同时也对KF-60L和KFR-70L产生风阻的各部件:进气面板、箱体、蒸发器,分别进行了风阻试验,结果表明:在较好的进气状态下,柜式空调器箱体的风阻占有最大的比例,依次是蒸发器与进气面板;进气状态的恶劣将会使整机风阻明显增高,性能变差.     

空调器离心风机内流场的PIV试验与CFD仿真对比分析

采用粒子图像测速仪PIV,对柜式空调室内机离心风机叶轮出口内部流场进行了试验研究,揭示了离心风机沿叶高方向叶轮出口速度分布特性.通过CFD数值分析,得到了柜式空调室内机离心风机叶轮出口流动特性,结合PIV与CFD流场对比,验证了CFD方法的正确性.根据CFD数值模拟结果,获得了离心风机入口与导流圈间隙处的流动特性,并设计了一款新的离心风机,在满足生产装配要求的最小间隙条件下,改善了离心风机与导流圈间隙处的流场,降低紊流噪声,提高叶片在叶轮进口段的利用效率.试验测试表明,新设计的离心风机相比原来的离心风机,在不同转速下,风量略有提升,噪声声压级均可降低1 dB/A,功率下降2～5W,同时风叶重量减轻了350g(26.5％),降低了离心风机成本.     

离心风机噪声特性的测量与分析

一、概述立柜式空调机是室内的空气调节装置,其噪声必须限制在一定的范围之内。目前,国内立柜式空调机配套用风机尚没有系列化、标准化的产品,风机噪声大,影响了整个立柜式空调机组的性能和推广。为此必须研制新型低噪声系列化的风机。为了评定离心风机的噪声特性,为研制低噪音风机提供参考,我们根据GB 2888-82《风机与罗茨鼓风机噪声测量方法,对美国TRANE公司制造的7.5大卡/时立柜式空调机组配套用     

内藏式空调室内机噪声控制研究

为了控制内藏式空调室内机的噪声,运用分步运转、频谱分析等方法判断出主要噪声源。根据1／3倍频程分析的结果,采用穿孔结构导流装置实施噪声控制方案,并对降噪结果运用Zwicker理论的噪声客观评价方法等观点进行分析。实践表明,此方法能有效地控制空调室内机的噪声,改善了噪声的频谱,降低了噪声的总响度和尖锐度,噪声控制后流量损失小于1％。     

基于Fluent的空调室内机风道结构噪声研究

为了研究风道结构对空调室内机噪声的影响,采用Fluent软件对某型空调室内机的流场进行了仿真,仿真过程考虑了热交换器对气流的阻碍作用,将其模拟为多孔介质流动。通过FW-H模型分别对以蜗舌、蜗壳和叶片为噪声源而产生的噪声进行了计算,并与空调室内机噪声测试实验的结果进行了对比,误差在允许的范围内。在尽量保持足够气体流量的前提下,以此模型为基础,通过调整蜗舌间隙与蜗壳前沿长度降低噪声,得到了空调室内机风道结构在此参数上的最优值。     

柜式空调室内机异音问题实验研究

异音问题是空调器生产企业在空调设计制造中经常会遇到的品质严重缺陷之一,本文针对某柜式空调室内机试制中出现的异音进行了实验分析,找到了问题的根本原因,整改后装机实验结果证明文中的分析是正确的。     

空调器多翼离心通风机整机定常流动的数值模拟

针对柜式空调器室内机多翼离心通风机的特点,采用计算流体动力学方法对其在设计工况时的整机内部流场进行了数值模拟,揭示了其内流场的基本特征.所得到的分析结果对多翼离心通风机的结构设计以及性能优化,提供了理论依据.     

空调室内机噪声源的识别与分析

介绍了某名牌空调室内机的声场测量方法,并通过对其噪声源进行分析,识别出风舌噪声、结构振动噪声和宽带噪声,并对其分别进行了说明.     

基于CFD的空调室内机的数值模拟

利用CFD软件,对分体式空调室内机的内部流场进行数值模拟,研究进口尺寸、面板与换热器间隙以及风道吸气角与空调风量的关系,从中寻找出各参数与空调风量的变化规律,该结果对今后空调的结构设计具有一定的指导意义。     

空调用贯流风机进气状态对其性能的影响分析

本文采用计算流体力学(CFD)的方法建立空调室内机流道的数值计算模型,定义了用于描述室内机贯流风机进气口气流方向的参数偏心度Φ.分析了室内机不同类型的前面板和换热器对贯流风机进气口流场状态速度分布,偏心度分布的影响,以及其与室内机性能的关系.为合理布置室内机前面板、换热器等结构,优化贯流风机进气口气流状态,提高贯流风机流量,降低贯流风机噪声提供参考.     

Experimental study of the effects of the cycle characteristics on the refrigerant-induced noise in system air-conditioner

The main sources of the refrigerant-induced noise can be classified 2 types according to its characteristics. One is due to the cyclic characteristics such as quality, velocity of the refrigerant, pressure drop and mass flow rate. The other is due to the structural characteristics such as distributed path pipe layout, distributor and expansion device. In this paper, the effects of cycle characteristics on the noise of multi-type system air-conditioner are investigated experimentally. In the indoor unit of multi-type air-conditioner, the variation of noise is examined when the in-flowing and out-flowing refrigerant to the indoor unit are 2-phase state according to its cycle control. And several factors are recommended in order to reduce the refrigerant-induced noise of the air-conditioner.     

烤烟用低压轴流风机性能试验研究

结合国内部分烤烟用低压轴流风机的发展趋势,针对KY7A系列不同结构风机,进行进气性能试验,依据轴流风机进气试验,给出测试得到的外部性能曲线。试验结果显示风机出口动静压、总压及噪声受叶片数量和叶片造型影响,为从整机角度选用合理的风机提供了依据。     

Experimental study on the optimum design of the flow-path system for a low noise indoor package air-conditioner

This study was carried out with the Taguchi method to find the optimum design condition of an indoor package air-conditioner (PAC) to minimize noise of operation. The goal of this study is to identify the optimum set of the control factors forming the flow-path system of an indoor PAC. The sound of operation and the number of revolutions of the fan of an indoor PAC were measured according to an orthogonal array of L₁₈(2³×3⁴) and used to find the smaller-the-better quality characteristic among the static characteristic analyses. As a result, the optimum condition of an indoor PAC for a low noise of operation is a set of 〈G1 A2 B1 C1 D1 E3 F1〉, with the judgment criterion of the optimum set based on the sound of operation, the number of revolutions and the cost of production. The sound performance of an indoor PAC operating under optimum conditions improved 1.8 dBA compared to that of the standard condition, and resulted in a reduction of about 45 RPM in the number of revolutions for the target flow-rate of 18.5 m3/min.     

Cavitation mode analysis of pump inducer

The onset of cavitation causes head and efficiency of a main pump to be reduced significantly and generates vibration and noise. In order to avoid these phenomena, the inlet of the pump is fitted with a special rotor called an inducer, which can operate satisfactorily with extensive cavitation. The motivation of this study is to find out cavitation modes from the inducer inlet pressure signals and event characteristics from outlet ones at various operating conditions. The cavitation modes are analyzed by using a cross-spectral density of fluctuating pressures at the inducer inlet. The time-frequency characteristics of wall pressures downstream of the inducer are presented in terms of event frequency, its duration time, and number of events by using the Choi-Williams distribution.     

动车组牵引变压器冷却风机气动噪声特性的试验和仿真分析

为研究动车组牵引变压器冷却风机的气动噪声特性,针对某型冷却风机进行气动噪声试验,得到在不同测点处的声压级和频谱特性。同时,针对该型风机建立仿真模型,模型中考虑电动机、支架等实际结构,结合计算流体力学方法和Lighthill声学比拟理论,对冷却风机的非定常流动特性和远场声场进行数值仿真,与试验数据进行对比。结果表明,通过大涡模拟得到的冷却风机噪声主要阶次与试验具有较好的一致性;在基于风机侧面评价点声压功率谱密度所估算声功率贡献量中,宽频带噪声占比为74.76%,是后续减振降噪的重点;阶次噪声占比为25.24%,结合仿真分析发现,阶次的主要来源为进风口动叶轮和出风口动叶轮处气流脉动压力所形成的偶极子声源,其中进风口第33阶次和出风口第10阶次最为重要。所得分析结果可为该型风机的气动性能和气动噪声的改进提供切实可行的参考依据。     

Experimental investigation on aero-acoustic characteristics of a centrifugal compressor for the fuel-cell vehicle

A variety of centrifugal compressors are used in various fields of industry such as aircraft, home appliances, and vehicles. Comfort and quietness are important in these uses. As a result, noise has become an important consideration in compressor design besides the conventional performance parameters such as efficiency and pressure ratio. However, compressor noise has been difficult to understand because of the lack of information. The aim of this paper is to investigate the aero-acoustic characteristics of a centrifugal compressor for the fuelcell vehicle by experiments. The existing compressor system is modified to measure the internal pressure fluctuation at the impeller inlet, the impeller outlet and the diffuser outlet. Four microphone probes are also installed to determine the external noise levels and spectra of the compressor in an airtight room according to the RPM and mass flow rate. The test results show the possibility to tell the relative noise level of a centrifugal compressor with the internal pressure data. The external microphone signals have relation to the internal pressure signals. They have similar patterns and spectra. It is a noteworthy phenomenon because it is easier and inexpensive to predict pressure behaviors than noise characteristics of centrifugal compressors. The dominant noise source is the tonal noise during normal operation. But the broadband noise component due to the turbulent flow in the compressor increases during low flow rate operation. Computational simulations are carried out to describe these phenomena and to identify noise indicators. The turbulence kinetic energy and the pressure distribution obtained from CFD results may be indicative of the relative noise intensity of the compressor. The experimental facility, instrumentation and simulation conditions are described, and the results are presented in this paper.     

家用空调压缩机的流体声和消声

在分析空调压缩机的噪声与声源的基础上，对流体声及其消声技术作了详细阐述，并提出进一步的研究方向。     

Identification of noise sources in scroll compressor for air-conditioner

Low noise of air-conditioners is one of the most important issues because of the users’ strong demand. The main source of noise in an air-conditioner is the compressor. Therefore, noise reduction in a compressor is quite significant as an element technology in the air-conditioner field. Recently, scroll compressors are widely used, because they feature low noise, due to less pulsation of gas pressure, than that of rotary compressors. For reduction of noise, the source of noise must be identified. This paper presents a detailed analysis to identify the noise source and shows the dominant factors of noise of the scroll compressor, which will make it possible to design a scroll compressor with low noise.