Novel Integrated Control of Fluid-borne Noise in Fluid Power Systems

液压流体动力广泛应用于陆、海、空运输、工程机械、工业机械、农业机械、石油天然气、矿山和国防等领域。然而，液压系统本身就非常嘈杂，需要采用新的流体传播噪音（FBN）衰减技术，以达到健康与安全执行“2005年工作噪音控制条例”中所记录的可接受和安全的噪音水平。可见，低噪声液压机可以显著改善人们的工作环境和生活质量。液压系统通常效率低下，平均效率为21%。根据最近一项名为《2011年美国流体动力行业影响（能源、排放和经济）评估》的研究，效率平均提高5%可以节省0.51千万亿英热单位的能源和101亿美元，同时减少二氧化碳排放超过3395万吨。根据最近完成的研究项目（EPSRC资助EP/H024190/1）的发现，一些新技术，如“数字”流体动力，有望大大降低能量损失，但会受到更高噪音水平的阻碍。有效的噪音控制技术应该能够使用这些更高效的液压系统，从而大大减少燃料消耗和二氧化碳排放。液压回路中的噪声主要表现为FBN噪声、结构噪声和空气噪声。FBN是由泵和马达或“数字”液压系统产生的非定常流引起的，并在系统中传播，引起振动或结构传递噪声，进而引起空气传递噪声。传统的噪声控制措施可能导致额外的功率损失。不必要的噪音也会消耗能量并产生热量，这可能导致机器不稳定和故障。针对噪声控制和节能方面的工程挑战，本课题是对一种新型液压机综合降噪系统的适时研究。该研究将是世界首例，并将采用一种新的集成噪声控制方法，结合主动和被动控制方法，为流体动力系统获得有效、鲁棒和高带宽的噪声衰减。独特的是，这种新方法允许主谐波压力脉动被主动衰减器衰减，高频噪声被被动调谐柔性软管抵消，而不会损害系统的动态响应。该方法能显著提高系统的降噪性能。PI研究的通用集成FBN控制系统的仿真结果表明，采用主动控制方法和被动控制方法分别实现了55dB和40dB的衰减。研究成果将提供有效的解决方案，以取代传统的噪音控制设备，并为英国和世界范围内更安静的流体动力机器的发展提供投入。实验结果将为将集成FBN控制系统和设计方法应用于传统和“数字”液压机提供信心。这项研究将保持我的研究小组独特的世界领先地位，并加速研究影响，以确保英国保持国际竞争力。这项工作将确保英国在全球液压元件市场的重要作用，预计到2020年将达到678亿美元，并进一步加强英国在欧洲液压市场的领先地位。这也将有助于确保英国有能力应对水利工程中的噪音挑战，并拥有研究能力和定量技能，以应对未来可能面临的全球环境和能源挑战。

Hydraulic fluid power is widely used in land, sea and air transportation, construction machinery, industrial machinery, agricultural machinery, oil and gas, mining and defence. However hydraulic systems are inherently very noisy and new techniques for fluid-borne noise (FBN) attenuation are needed to achieve acceptable and safe noise levels as documented in The Health and Safety Executive 'The Control of Noise at Work Regulations 2005'. It is obvious that low-noise hydraulic machines can significantly improve people's working environment and quality of life.Hydraulic systems are often inefficient with an average efficiency of 21%. An average 5% improvement in efficiency can save 0.51 quadrillion Btu of energy and US$10.1 billion while reducing carbon dioxide emissions by more than 33.95 million metric tons, according to the recent study of 'Estimating the Impact (Energy, Emission and Economics) of the US Fluid Power Industry, 2011'. Some new techniques such as 'digital' fluid power promise much lower energy losses but are hampered by higher noise levels according to the findings from the recently completed research project (EPSRC grant EP/H024190/1). Effective noise control techniques should enable use of these more efficient hydraulic systems, resulting in considerable reduction in fuel consumption and carbon dioxide emissions.The noise in hydraulic circuits presents itself as FBN, structure borne noise and air borne noise. FBN is caused by the unsteady flow produced by pumps and motors or 'digital' hydraulics, and propagates through the system causing vibration or structure borne noise, which in turn causes air borne noise. Traditional noise control measures can lead to additional power losses. Unwanted noise also consumes energy and generates heat which may lead to machines instability and failures. In response to the engineering challenges in noise control and energy efficiency, this proposal is a timely investigation into a novel integrated noise attenuation system for hydraulic machines. The proposed research would be a world first, and will apply a newly integrated noise control approach engaging both active and passive control methods to obtain an effective, robust and high-bandwidth noise attenuation for fluid power systems. Uniquely, this new approach allows the dominant harmonic pressure pulsations to be attenuated by the active attenuator and high frequency noise to be cancelled by passive tuned flexible hoses without impairing the system dynamic response. This novel methodology can significantly improve the noise attenuation performance. Simulations of a generic integrated FBN control system studied by the PI show that 55dB attenuation was achieved, while 40dB was achieved by only using the active control method and 20dB was achieved by using the passive control approach, respectively.The research outcomes will deliver effective solutions to replace traditional noise control equipment and provide input into the development of quieter fluid power machines in the UK and worldwide. The experimental results will provide confidence in applying the integrated FBN control system and design methodology for both conventional and 'digital' hydraulic machines. This research will maintain my research group's unique world leading position and accelerate research impact to ensure the UK remains internationally competitive. This work will ensure the UK's significant role in the global market for hydraulic components which is projected to reach US$67.8 billion by 2020 and further enhance the UK's leading position in the European hydraulic market. It will also help ensure that the UK is well equipped to deal with noise challenges in hydraulic engineering and has the research capability and quantitative skills for worldwide environmental and energy challenges it may face in the future.