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Modeling, Measurements and Analysis of Gas-Flow Generated Noise From Twin-Screw Compressors

  • January 2000
  • Conference: International Compressor Engineering Conference PURDUE 2000
Authors:
Bo Ivar Sångfors at BoSångfors Consulting
Bo Ivar Sångfors
  • BoSångfors Consulting
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This paper gives a short presentation of a method for the computer simulation of noise caused by the gas pulsations, created from the opening and closing of inlet and discharge ports of twin-screw compressors. The method takes into account influences from lobe combinations, wrap angle, length/diameter ratio, leakage through blowhole and clearances at mesh, rotor tips and discharge end. Oil content in the gas as well as resonance in the compressor discharge chamber and downstream piping are also taken into consideration. Comparisons between calculations and laboratory measurements, as well as analysis of the influence of different design parameters, are presented and discussed.
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Supplementary resource (1)

This is an addition to the PURDUE paper: " Modeling, Measurements and Analysis of Gas-Flow Generated Noise From Twin- Screw Compressors " Influence of outlet blanking upon SPL(Sound Pressure Level) of a Screw Compressor Outlet
Data
June 2016
Bo Ivar Sångfors
... Andrews et al. [12] measured the sound intensity, sound power, and gas pulsation from refrigeration screw compressors under different loads in the laboratory, and provided the law of gas pulsation variation with exhaust pressure. Gavric [13], Sanfors [14], and Tanttari [15] analyzed the noise and vibration due to the pressure oscillation of the suction and exhaust chamber caused by intermittent gas flow through the suction and exhaust ports of the compressor. Overall, the results of previous research and analysis indicate that the main noise of screw compressors is mechanical vibration noise and hydrodynamic noise, and gas pulsation is the main noise excitation source. ...
... Koai [16,17] and Sangfors [14] concluded that the pressure difference between the compressor working chamber and the exhaust chamber is an important factor affecting gas pulsation. When the pressure in the exhaust chamber is equal to the design pressure, according to the internal volume ratio, the gas pulsation is minimal. ...
... Andrews [10] experimentally analyzed the effect of compressor load on gas pulsation, finding that as the compressor load increases, the gas pulsation increases and noise increases. Sangfors [14] and Mujic [11] determined the number of teeth of the screw compressor rotor also affects gas pulsation, and compressors with more rotor lobes generate lower gas pulsation. Wu [20] established a one-dimensional unsteady gas flow theory to study the effect of compressor speed on gas pulsation, finding that as the speed increases, the compressor gas pulsation also increases. ...
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... Fujiwara et al. [2] comprehensively measured the vibration and noise of a screw compressor. Gavric [3], Sangfors [4], and Tanttari [5] conducted theoretical and experimental analysis of the noise and vibration caused by pressure oscillations in the suction and discharge chambers caused by intermittent gas flowing through the suction and discharge ports of a compressor. Subsequently, Song et al. [6] measured the sound intensity of the main noise sources of a compressor and determined that the motor and inlet air pulsation were the main noise sources. ...
Performance Research and Optimization of Sound Insulation Hood of Air Compressor Unit
Article
Full-text available
  • Nov 2021
The noise control of a compressor has always been a hot spot in the field of industrial application. In this paper, the air inlet structure of the sound insulation hood of an air compressor unit was studied and improved. Acoustic finite element numerical simulation analysis of the sound insulation hood model was carried out using the acoustic software LMS Virtual Lab Acoustics. The simulation results were compared with the experimental data to verify the correctness of the model, and the theoretical results showed a good agreement with the experiment data. The sound insulation performance of the sound insulation hood under different structures was also investigated in this paper. The results show that the main source of unit noise leakage is outward radiation through the air inlet. In addition, the noise at the air inlet of the unit and the overall noise were significantly reduced compared with the traditional sound insulation hood upon installing 120° and 90° diaphragm structures on the inner wall of the air inlet. The optimization results show that the noise reduction effect of the sound insulation hood with a 90° diaphragm structure was better than that with a 120° diaphragm structure.
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... 月 2020 年 7 月 陈文卿等：半封闭变频螺杆制冷压缩机降噪方法及试验 189 0 前言 双螺杆制冷压缩机凭借其结构简单、 效率优越、 性能稳定等优势，在 20～400 kW 的中等容量蒸汽 压缩式制冷/热泵系统中，已逐渐成为商用、工业用 制冷/热泵设备的主流配置 [1] 。半封闭螺杆制冷压缩 机由于将压缩机与电动机封装在同一壳体内，不但 能利用低温吸气冷却电动机无需设置轴封，还能隔 离压缩机运行噪声，在螺杆式制冷/热泵机组中广泛 使用。随着螺杆压缩机的不断更新换代，性能不断 提升 [2][3][4][5] ，振动噪声的控制和降低已逐渐成为螺杆压 缩机技术发展所面临的新要求，同时也是各生产厂 家提升其自身产品竞争力的关键之一 [6] 。 FUJIWARA 等 [7][8][9][10][11] 对辨识螺杆压缩机主要的振 动噪声源开展了大量的研究工作，其所针对螺杆压 缩机运行过程中的振动噪声所进行的试验测试结果 均表明处于气流脉动基频及其整数倍频率的振动噪 声值较大，由工作容积与吸、排气孔口周期性连通 所引起的气流脉动是螺杆压缩机振动噪声的主要诱 因，且因排气腔内气体密度大，排气气流脉动所诱 发的气动噪声更为显著。沈九兵等 [12] 建立了半封闭 螺杆制冷压缩机排气流场模型，利用 Fluent 软件和 LMS 软件模拟得到了压缩机排气噪声的频谱图，并 通过试验研究对模拟结果进行了验证。MUJIC 等 [13] 研究了螺杆压缩机的排气孔口几何参数对排气腔内 气流脉动的影响，得到了排气腔内气流脉动会随着 排气孔口几何参数变化而变化的结论。WU 等 [14] 针 对螺杆空气压缩机的运行转速对其排气压力脉动特 性的影响进行了试验研究，结果表明随着压缩机转 速的增加，其排气气流脉动幅值不断上升，振动噪 声显著增强。LINKAMP 等 [15] 则建立了螺杆压缩机 排气压力脉动计算的一维热力学模型，针对排气压 力对其压力脉动幅值的影响进行了理论和试验研 究。螺杆压缩机气流脉动的研究是降噪设计的理论 依据。WU 等 [16] 针对半封闭螺杆制冷压缩机设计了 排气脉动阻尼器，并试验验证了脉动阻尼器对气流 脉动的衰减作用。MUJIC [17] ...
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... Characteristics of suction flow periodically change as a result of variation of suction area and suction speed, hence suction pressure pulsation, lower than discharge pressure pulsation, is induced. Sangfors et al. conducted a lot of research to identify main NVH sources in twin screw compressor [5] . The results all showed that NVH values at fundamental frequency of gas pressure pulsation and its harmonic frequencies were relatively high. ...
Characteristicsx and suppression of NVH in twin screw refrigeration compressors
Article
Full-text available
  • Sep 2019
Characteristics of NVH (Noise, vibration and harshness) in twin screw refrigeration compressors, mainly caused by mechanical vibration and turbulent gas flow, are discussed in detail. According to the different generation mechanism, suppression methods of mechanical NVH and hydrodynamic NVH are proposed, respectively. Mechanical NVH is related to rotor profile, bearings, lubricating conditions and maching precision, while hydrodynamic NVH is inevitable and severe for all positive displacement compressors due to gas compression and turbulent flow. Concluded from three cases of NVH suppression for semi-hermetic twin screw refrigeration compressors, half-wave method based on acoustic interference theory, pulsation damper evolving from Helmholtz resonator and broadband perforated tube silencer are effective paths to alleviate hydrodynamic NVH in twin screw refrigeration compressors without bringing in extra energy losses.
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... The fluid sources such as gas pulsation contribute in noise which is more evident in the filling and discharge processes through the ports (see [12]). The simulation package based on the mathematical modeling of the excitement forces and pressure waves helps the designer with the optimization of, among others, transmission mechanism and port design to reduce the noise level (see [13]). ...
The workflow of rotor machine development: design phases, steps and tools of the development process
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  • Nov 2018
In this work we present an overview of the workflow of rotor machine§ development, focusing on twin-screw compressors and expanders. The rotor machine development process consists of an orchestrated activity of specification, design and verification where individual phases, steps and tools contribute significantly in developing cutting-edge technology and delivering sustainable solutions. Our goal is to present those phases, steps and tools with relevant examples, highlight the development challenges and argue the inevitable deviations of real-life condition from the original specification. We believe that this contribution will shed light upon the essential elements of the rotor machine development process, something that benefits the entire community from academia and suppliers to end users.
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... Tanttari 6 reported that the discharge gas pulsation smoothly increased with the static discharge pressure. Sangfors 7,8 computationally studied the noise caused by gas pulsation. The influence of lobe combination, wrap angle, length/diameter ratio, leakage through blowhole and clearance at mesh, rotor tip, and discharge end was evaluated. ...
Investigation of characteristics of discharge pressure pulsation in a twin-screw refrigeration compressor
Article
Full-text available
  • Jun 2018
In this paper, characteristics of discharge pressure pulsation in a twin-screw refrigeration compressor are investigated. A thermodynamic model is developed and validated using data from a comprehensive experimental study. This validated model is then applied to investigate effects of key parameters including condensing temperature, compressor rotational speed, super-feed pressure, part-load operation, and design parameters on the discharge pressure pulsation. The results showed that the discharge pressure pulsation was mainly due to periodic variations of mass and energy flow from the working volumes to the discharge chamber. As the condensing temperature increased or decreased from the design condition, the compressor was in either over- or undercompression leading to an increase in the amplitude of the pressure pulsation. The gas super-feed pressure could increase the pressure pulsation at condensing temperatures below the design value and reduce the pressure pulsation at condensing temperatures above the design value. The analysis also demonstrated that the pressure pulsation was lower at part-load conditions. However, the compressor rotational speed increased both the amplitude and frequency of the pressure pulsation. Theoretical analysis of design parameters indicated that a large discharge volume with a high number of lobes could lower the pressure pulsation. These analyses provide useful information for the compressor design and optimization.
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CFD simulation for the internal pressure characteristics of an oil-injected twin-screw refrigeration compressor
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The internal pressure characteristics of an oil-injected twin-screw refrigeration compressor was studied using a full 3D CFX model, and the hexahedral moveable meshes of the twin-screw domain were generated by the professional mesh tool SCORG. The gas pressure throughout the whole working process was investigated to disclose its distribution feature. The working pressure at different locations, such as the inner surface of the screw rotor housing, the oil injection paths, the male screw groove, the internal suction and discharge flowing paths, were all captured and analyzed. The simulated pressure inside the screw working chamber agreed well with the experimental results in both time and frequency domains. The pressure pulsations in the compression section acting on the inner surface of the screw rotor housing presented higher levels than the data in the other domains. The highest pulsation level occurred on the location where could record the whole discharge process of the internal ports. Under the high oil flowrate conditions, due to the different influences of the fluid hammer effect, the pressure pulsation increment of the axial oil injection outlet was much larger than that of the radial oil injection outlet. The orifice on the oil path could help reduce the influence of the fluid hammer. Finally, several suggestions were given based on the simulation findings.
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Study on the noise reduction methods for a semi-hermetic variable frequency twin-screw refrigeration compressor
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The semi-hermetic twin-screw refrigeration compressors have been widely applied in middle size refrigeration and heat pump systems. The operation noise of the twin-screw refrigeration compressor is becoming a crucial limitation for their applications. Two noise reduction methods for a semi-hermetic variable frequency twin-screw refrigeration compressor were developed. One is the end face attenuation passage and the other is the discharge pipe damping. The former reduces the gas pulsation amplitude in the discharge chamber which is the main noise source. The discharge pipe damping is comprised of several Helmholtz resonators and is installed in the discharge pipe within the compressor. Methods for the flow field and sound field simulation of the compressor were further proposed to verify the noise reduction effect of each method. Moreover, an experimental study was carried out to evaluate the general effect when the two method were applied in a real compressor. Both simulation results and experimental results demonstrated that both noise reduction methods had good effect. According to the experimental results, the actual operation noise level was no more than 85.5 dBA and the mean noise reduction value was in the range of 5.0 dBA ∼10.0 dBA when the rotational speed increased from 3000 rpm to 5100 rpm.
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Noise Control of a Twin-Screw Refrigeration Compressor
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Twin-screw compressors are widely used in refrigeration systems, but noise is a serious problem during operation. Gas pulsation is the main noise excitation source in twin-screw compressors, and the noise has significant fundamental harmonic characteristics. In this study, the noise characteristics of a screw compressor were experimentally investigated, which provides insight into the noise control technology of the compressor. The analysis incorporated the noise control theory and the structural characteristics of the experimental compressor. The noise reduction schemes including half-wavelength tube, Helmholtz resonator, and multi-cavity series muffler were proposed, and the noise attenuation performances of these methods were studied experimentally. The results showed that application of these noise reduction strategies significantly reduced the noise level by 10.7 dBA, 10.9 dBA, 7.2 dBA, and 10.2 dBA at the male rotor side, the female rotor side, the suction side, and the exhaust side, respectively. Comparative test results indicated that the use of the exhaust muffler and the attenuation scheme on the exhaust bearing block was most effective and it reduced the compressor noise level by 8.17 dBA. These results provided useful guidance for designing a quiet compressor.
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Experimental study of lubricating oil impact on pressure pulsation for twin-screw refrigeration compressor
Article
An experimental investigation on pressure pulsations of twin-screw refrigeration compressor was conducted. The pressure pulsation energy at different radial locations on the screw housing, inside the discharge chamber, and the energy transmitting to downstream components during the working process were all tested. Various oil parameters have been investigated to disclose its influence on the pressure pulsation energy of twin-screw refrigeration compressors. With the total oil flow rate increasing, pressure pulsation was found attenuating above the 1st order of pumping frequency, while the amplitude reduction was found depended on the oil injection locations and oil distributions obviously. The final compression pressure inside the screw lobe cavity before the internal discharge port opening was found to be much lower than the expected value based on the built-in radial Vi, and the pressure continued increasing until the axial port opening around 5.45°. Several suggestions about design for lower pressure pulsations were recommended based on test findings.
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Computer Simulation of the Oil Injected Twin Screw Compressor
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Full-text available
  • Jan 1984
In this paper a physical model for prediction of oil-flooded twin screw compressor performance is presented and discussed. Calculation results are presented.
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An Analytical Study of Intake Tuning for Helical Rotor Expanders
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  • Sep 1985
A rather complete mathematical model of a circular lobed helical rotor expander has been modified to include dynamic interactions with the intake plumbing. Parametric studies were performed to determine the effects of these dynamics on overall machine performance. It was found that variations in the intake geometry caused substantial variations in output power for a given steady state RPM: however, actual supercharging using passive intake tuning was not possible. © Martinus Nijhoff Publishers, Dordrecht and Freund Publishing House
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Computer Simulation of Gas-Flow Generated Noise from Twin-Screw Compressors
  • 707-716
  • B Sfmgfors
B. Sfmgfors "Computer Simulation of Gas-Flow Generated Noise from Twin-Screw Compressors" Proceedings of the 1999 ImechE Int.Conf on Compressors and their Systems, pp 707 -716.