• 한국생산제조학회지
• /
• 제9권1호
• /
• pp.88-95
• /
• 2000

In this paper, an expansion-resonator type pulsation attenuator is proposed to absorb and attenuate flow an pressure ripple with high frequencies generated from hydraulic control systems. The basic principle of a pulsation attenuator proposed here is applied to propagation, reflection, absorption of pressure waves at the cross section of discontinuity and resonance in the pipeline. It has advantage of the compact size and high degree fo freedom for installation in hydraulic systems. The design scheme based on distributed parameter pipeline system with dissipative viscous compressible model is developed. To investigate the reduction of flow and pressure ripple with high frequencies produced by swash plate type axial piston pump, two kinds of attenuators are manufactured. It is experimently confirmed that the spectral intensity of flow and pressure ripple with high frequencies from the pump are reduced up to about 20$^{\circ}$~30dB by using attenuators proposed here. The calculated results were in good agreement with the measured values. From there sults of this study, it is shown that an expansion-resonator type pulsation attenuator is effective in a wide frequency ranges to attenuate the flow and pressure ripple from hydraulic components.

• 설비공학논문집
• /
• 제12권5호
• /
• pp.448-456
• /
• 2000

For piping line systems associated with a double-acting reciprocating compressor, an analytical study has been made on the gas pulsation in piping lines and its effects on the compressor performance. The transfer matrix which relates mass flow rate to the gas pulsation downstream of the compressor valve can be obtained by an acoustic model for piping line systems which include snubber and after-cooler with the aid of four pole theory Since mass flow rate is affected by the pressure pulsation in the pressure plenum, while the latter being determined by the former, iteration in the calculation should be made for convergence. The gas pulsation in pipings is found to have an adverse effect on the compressor's performance, and the magnitude of the gas pulsation can be lowered by increasing snubber volume.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.53-56
• /
• 2007

The reciprocating type hydrogen compressor is occurred by the pulsation from the mechanism and this pulsation is make much noise and vibration. Therefor snubber is installed for pulsation decreasing. The five type snubber models were designed for increasing pulsation amplitude reduction and decreasing pressure loss in snubber considering output pipe location as design value. And the pressure flued analysis is carried by CFD. In this paper, each type snubber according CFD result are analyzed by the MSC/NASTRAN to identify the vibration characteristic of each type. The vibration results are compared with CFD results.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제13권1호
• /
• pp.794-803
• /
• 2021

The instantaneous acceleration affects the performance of the water-jet pump obviously. Here, based on the user-defined function, the method to simulate the inner flow in water-jet pumps under acceleration conditions was established. The effects of two different acceleration modes (linear acceleration and exponential acceleration) and three kinds of different acceleration time (0.5s, 1s and 2s) on the performance of the water-jet pump were analyzed. The results show that the thrust and the pressure pulsation under exponential acceleration are lower than that under linear acceleration at the same time; the vapor volume fraction in the impeller under linear acceleration is 27.3% higher than that under exponential acceleration. As the acceleration time increases, the thrust gradually increases and the pressure pulsation amplitude at the impeller inlet and outlet gradually decreases, while the law of pressure pulsation is the opposite at the diffuser outlet. The main frequency of pressure pulsation at the impeller outlet is different under different acceleration time. The research results can provide some reference for the optimal design of water-jet pumps.

• Journal of Advanced Marine Engineering and Technology
• /
• 제32권8호
• /
• pp.1116-1122
• /
• 2008

The reciprocating type hydrogen compressor has a pulsation due to the reciprocative characteristics which results in noise and vibration. Snubber is installed for the relaxation of pulsation, but it causes reduction of compressor efficiency because of pressure loss. Five types of snubber were modeled for the numerical investigation of the effect of the relative position of inlet and outlet and buffer angle on the pulsation amplitude and pressure loss. MSC/NASTRAN is used as a numerical tool to identify the vibration characteristic of each type. Frequency responses in forced vibration mode are compared for various cases and buffer angles.

• 한국정밀공학회지
• /
• 제29권7호
• /
• pp.793-798
• /
• 2012

Oil gear pump is used for the cooling pump system of commercial vehicle. The hydraulic pulsation pressure of oil gear pump is one of the most important reasons for the vibration and noise of the pump. In this study, the several hydraulic factors acting on oil gear motor are analyzed by CFD in operation of cooling system. Forced vibration analysis due to hydraulic pulsation pressure is analyzed by FEA for predicting deformation and equivalent stress.

• 설비공학논문집
• /
• 제12권3호
• /
• pp.302-308
• /
• 2000

The major source of noise in air-conditioner is a compressor. Therefore, noise reduction in a compressor is quite significant as an element technology in air-conditioner field. Recently, a scroll compressor is widely used, because a scroll compressor features lower noise, due to less pulsation of gas pressure, than that of the rotary compressor. During a past noise reduction effort on a scroll compressor, noise radiation from the discharge portion of the hermetic shell was identified as the major contributor to overall noise. For a reduction of noise, the source of noise at the discharge portion must be identified. This paper presents detailed analyzes for the discharge pressure pulsation and cavity resonance at discharge space, which will make possible a low noise design of a scroll compressor.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.614-619
• /
• 1997

The hydraulic pressure pulsation has on the effected on the acoustic nosie and control performance of the hydraulic-servo system. The Helmholtz attenuator introduction on the hydraulic line is an efficient device to reduce the hydraulic pulsation. The salient feature of causing hydraulic pulsation and the frequency characteristics of Helmholtz attenuator are studied. The hydraulic filter design parameters such as the locating position, connecting orifice area and accumulator volume are mathematically analyzed. The instrumental works are carried out with the remarkable reduction of the hydraulic pressure pulsation magnitude and the acoustic noise level.

• 한국자동차공학회논문집
• /
• 제15권4호
• /
• pp.132-138
• /
• 2007

Experimental results of pulsating pressure behavior inside a chamber have been confirmed by computational work. Inside-cylinder pressure shows unstable condition at low rpm. This is caused by plate-type suction valve. It has effect up to inlet of the chamber. But trembling phenomenon is reduced as the pressure is enlarged by increasing the rpm. Result comparison between experimental and numerical analysis shows pulsation reduction is affected by the chamber. We can confirm that compressible effect of the working flow is shown at chamber inlet by increasing rpm. On the other side, this effect is declined at chamber outlet by increasing rpm. It means outlet pressure is going on balance with atmosphere pressure. Buffer plate-type chamber has efficiency of pulsation flow reduction.

• 대한의용생체공학회:의공학회지
• /
• 제23권5호
• /
• pp.391-395
• /
• 2002

수두증 환자를 치료하기 위해 머리에 시술 되는 션트밸브가 받는 뇌압 펄스가 밸브의 유량조절 특성에 미치는 영향을 수치적으로 해석하였다. 션트밸브를 통한 유량을 계산하기 위하여 밸브 다이아프램이 형성하는 유량 오리피스를 모델링 하여 맥동압력과 변동하는 압력에 의한 다이아프램의 움직임을 고려하였다. 연구 결과, 압력 펄스와 이에 따른 다이아프램의 움직임에 의하여 유량이 40% 이상 증가함을 보였다. 이 결과는, 뇌실에 시술 되는 션트밸브의 압력-유량 조절특성이 제조 직후 맥동이 없는 유량을 공급하는 시린지 펌프를 사용하여 구한 실험 결과와 상당히 다르다는 사실을 보여주었다.