Hydraulic drives remain essential across construction, mining, agriculture, marine, and aviation. Their widespread adoption comes from a high power-to-weight ratio, efficient energy transmission, and ease of automation. Yet one factor that is often overlooked—hydraulic hose length—can dramatically influence how pumps and lines behave under pulsating flow. In some cases, an incorrect hose length can create conditions for hydraulic resonance, amplifying pressure pulsations and increasing vibration levels.
A recent study, published in Scientific Reports, investigated this phenomenon by analysing how steel hoses of different lengths respond to pressure pulsations generated by a positive displacement pump. The research was led by Professor Michał Stosiak and Dr Paweł Bury of the Wrocław University of Science and Technology, working with Associate Professor Mykola Karpenko of Vilnius Gediminas Technical University.
The team combined modelling with experimental verification. Their model predicted the occurrence of resonance at specific hose lengths and excitation frequencies, and the lab tests confirmed this behaviour. At certain lengths, outlet pressure pulsations were amplified while inlet pulsations were dampened, showing clear resonance conditions. These amplified waves not only affected pressure stability but also caused the hoses themselves to vibrate, introducing additional mechanical stresses into the system.
Results revealed a consistent relationship: resonance occurs when the hose length aligns with the wavelength of pressure waves in the fluid. Longer hoses shifted resonance into lower frequencies, while shorter hoses magnified dynamic pressure amplitudes at higher frequencies. For instance, a 1.25-metre hose exhibited resonance at significantly higher frequencies compared to a 2-metre hose, where resonance occurred earlier in the frequency range. This detail is particularly relevant for equipment that operates across variable pump speeds.
The implications are practical. By avoiding hose lengths that coincide with resonance conditions, engineers can reduce pulsation amplification, limit vibration, and mitigate noise. This not only protects the hydraulic components themselves but also reduces environmental and human impacts from system vibrations, which can extend into harmful low-frequency ranges.
For pump professionals, the message is clear: hose length is not simply a routing convenience. It directly affects the dynamic behaviour of the hydraulic system and should be treated as a design parameter just as critical as pressure rating, flow rate, or material selection.
