• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.1005-1009
• /
• 2002

The objective of this research is to suggest the noise prediction method of the centrifugal compressor. It is focused on the Blade Passing Frequency (BPF) component which is regarded as the main part of the rotating impeller noise. Euler solver is used to simulate the flow-field of the centrifugal compressor and time-dependent pressure data are calculated to perform the near-field noise prediction by Ffowcs Williams-Hawkings (FW-H) formulation. Indirect Boundary Element Method (IBEM) is applied to consider the noise propagation effect. Pressure fluctuations of the inlet and the outlet in the centrifugal compressor impeller are presented and Sound Pressure Level (SPL) prediction results are compared with the experimental data.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.785-789
• /
• 2002

Sound measurement experiments and Finite Element analysis are carried out to understand the characteristics of the noise propagation and structure of the compressor in this research. Noises generated from the compressor on various conditions are measured to classify the transmission path of the noise propagation with respect to the sources. The experiment results show that noises attributed to the shell bending resonant modes accounts fer a major portion of the spectra and that damping spring of the discharge pipe have a damping effect on some frequency range. Constructions of the FE model show that the curvature of the upper shell is very important for the resonance of the upper shell. And, present upper shell has a difficult shape to be manufactured. And, in this research, shape optimization is conducted to increase the strength of the shell for the reduction of the noise. Sound spectrum of noise from the modified compressor verified the sound reduction.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.1
• /
• pp.83-92
• /
• 2000

Sound intensity method is well known as a visualization technique of sound field or sound propagation in noise control. Sound intensity or energy flux is a vector quantity which describes the amount and the direction of net flow of acoustic energy at a given position. Especially two dimensional sound intensity method is very useful in evaluating periodic characteristics and acoustic propagation mode of noise source. In this paper, we have studied the noise source Identification, acoustic sound field analysis, and characteristics of noise source of rotary compressor and scroll compressor for air conditioner using complex sound intensity method. Also we proposed a now method of time domain analysis which is used in evaluating of position of noise source in rotary and scroll compressor in this paper This paper presents the advantage, simplicity and economical efficiency of this method by analysing the characteristics of noise source with two dimensional complex sound intensity simultaneously.

• 연구논문집
• /
• s.33
• /
• pp.39-51
• /
• 2003

This paper deals with the noise measurement and evaluation method of a reciprocating air-compressor and its noise reduction. Lead-wrapping techniques are employed to identify the contribution of principal noise sources which are generally known as motor, belts, suction/discharge valves, moving piston, and flow-induced noise which are caused by edges or discontinuities along the flow path e.g. expansions, contractions, junctions and bends. As a result, it can be found that main noise sources of the air-compressor can be categorized by the suction/discharge noise, valve noise, and compressed-air tank noise. Based on the investigations, mufflers are designed to reduce both the suction/discharge noise and the compressed-air tank noise. Instead of the conventional valve plate, engineering plastics are used as a new one for the reduction of valve impact noise. In addition, attempts are made to reduce the valve noise propagation to the cylinder head and the compressor tank by using the insulation casings in the cylinder head. As a result of the countermeasure plans, it can be achieved that the noise reduction of the air-compress is up to 10 dB.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.1
• /
• pp.3-9
• /
• 2004

This paper introduces the experimental analysis of the resonator in the rolling piston type compressor for air conditioner. The resonator located between cylinder and hearing is a major factor in the noise reduction of the rotary compressor. Several shapes for the resonator which can be built in the space limitations are derived. Then optimal resonator type for the noise reduction is determined by noise tests. 6 design parameters of the type are found and optimal level for each design factor is deduced from Taguchi method.

• 유체기계공업학회:학술대회논문집
• /
• 2004.12a
• /
• pp.533-539
• /
• 2004

The rotary compressor is widely used for the air conditioner because it is efficient and compact. In recent, the need for silent and efficient compressors is much stronger than the past. The new type muffler was invented to reduce noise level and to improve efficiency. The new type muffler that has two side discharge holes and dome shape represents much lower overall noise level, especially noise levels around 1kHz than the old type one that has one center discharge hole In acoustic spectra. Also it has higher air conditioner efficiency by lower oil discharging amount of a compressor than old type one that has rectangular shape and two side discharge holes. The noise reduction and efficiency improvement effects of the new type muffler were verified by tests for rotary compressors and air conditioners.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.04a
• /
• pp.1000-1004
• /
• 2008

As performance of medical air compressor improve, the problem of noise increased. Noise is very important to medical air compressor because most of this installed inside of building. The main goal of this paper is show TPA (Transfer Path Analysis) result for contribution analysis using PAK system. Generally, the conventional TPA method consists of two steps. First, transfer functions between output sound and sources are measured by excitation experiment. Second, transferred sound in each transfer path is generated by multiplying the transfer function and the sound source signal. Then, if the output sound synthesized from all transferred sounds doesn't give good agreement with the measured output sound (i.e., the accuracies of the transfer functions are low), setting a suitable countermeasure guideline becomes difficult. For obtaining highly accurate transfer functions, eliminating correlations among transfer functions and noise included in the measured data are necessary. In the new method with PAK system, the vibration acceleration and sound signals around the sound sources and the output sound were measured simultaneously to obtain the transfer functions when compressor was operating. By applying PAK system, a highly accurate and efficient transfer path analysis method was developed that does not require an excitation experiment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.11b
• /
• pp.875-880
• /
• 2002

It is necessary to determine the vibration source and its transmission paths in order to develop a low-noise compressor. Through the use of multiple-input/single-output(MISO) mode1, the transmission paths of vibration within a reciprocating compressor have been investigated. In order to identify the transmission path, we measure the accelerations of the block and transverse vibrations of the line discharge tube. As outputs, vibrations of compressor shell were measured at three positions; cylinder head, one near the suction line, and the top of upper shell. The partial coherence function and transfer function are obtained ken the measured data, and the results are observed in order to determine vibration source and its influence on the shell vibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.79-82
• /
• 2004

In general, compressors for refrigerators are major noise source in home environment. The vibration originated from a pump of a compressor can make noise through suspension springs and a LDT(Line Discharge Tube). Especially for the inverter motor driven compressor, the vibration is more serious than it of the constant speed compressors. Because the operation frequency range of an inverter motor driven compressor is very wide from 1600 rpm to 4200 rpm. In this paper, we propose the numerical model to reduce vibration by designing weight balancers and grommets. Results for analytical investigations on the exciting force and moment at the pump mass center, weight balancers and exciting frequency variation are presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.478-485
• /
• 2003

Today, although there have been high technical developments of a compressor in the respect of its capacity, it has been so hard to develop in the respect of vibration and noise because mechanical structure of it has originally numerous vibration and noise. However, if we can grasp the point of systematic phenomena of vibration and noise through the understanding of dynamic characteristics in mechanical equipment, it may be possible to consider countermeasures. In this study about a reciprocal compressor, the part of its machinery is modeled as rigid body, and the part of its spring is modeled as flexible body, and then they are analyzed by DADS. Each rigid body and spring are connected with joint torque of a motor is applied to shaft, and pressure is applied to a piston so that a compressor can be revolved. Based on this modeling, influence of a compressor's vibration is analyzed through changes of offset, connecting rod and crank radius In the case of weight balance, it I produced after re-design, and then changes of vibration of a compressor's inside are checked through experiments. These analysis data may help set measures of reducing vibration of a reciprocal compressor.