<p>Hydraulic
systems have many applications in the construction, transportation, and
manufacturing sectors. Recent design trends involve systems with higher working
pressures and more compact systems, which are advantageous because of power
density increase. However, these trends imply higher forces and larger
vibration amplitudes while having lesser mass and damping, leading to higher
noise levels. Meanwhile, hydraulic machinery started prospecting new
applications with tighter noise regulations, a trend which was also pushed by
the electrification tendency in several fields of transportation and
agriculture. One method to attain noise mitigation is passive-noise canceling
techniques have the advantage of not introducing energy to the system. This
approach arranges pressure ripple waves in a destructive pattern by projecting a
hydraulic circuit's geometry, configuration, and features.</p>
<p> </p>
<p>This
dissertation aims to predict fluid-borne noise sources and investigate passive
noise-canceling solutions for multiple operations conditions targeting to
impact many hydraulic systems and a broad range of operating conditions. Primarily
a coupled system model strategy that includes a one-dimensional line finite
element model is developed. The line model predicts pressure wave generation
and propagation. The model features versatility since parameters like line
diameter and material can be discretized node by node. Simulations are compared
to measured data in a realistic novel hydraulic hybrid transmission for validation.
</p>
<p> </p>
<p>Subsequently,
an extensive numerical investigation is performed by setting fixed
parameters along the hydraulic lines' length and comparing several isolated
geometric properties in simulation. The developed line model is also used to
study the influence of line features such as diameter and extent of the
conduit. Cost-effective and simple passive solution solutions such as Quincke
tubes (parallel lines), expansion chambers, and closed branches are selected
and investigated on simulation. Four target pressure ripples are chosen as indicators
for summarizing passive line elements behavior. The frequency-domain behavior
of the pressure ripple peaks regarding the line's length is identified and
isolated in simulation at the 50-5000Hz frequency spectrum. An experiment test rig is designed to
implement these solutions and the experiments show three developed passive
elements as practical and effective solutions for reducing fluid borne noise sources.
The selected designs yielded noise source attenuation over most of the frequency
spectrum measured with piezoelectric pressure variation sensors and
accelerometers in different positions in the hydraulic circuit. Sound pressure
measurements detected reductions over 3dB in the best cases. </p>
<p> </p>
<p>Also,
a passive interference approach based on the principle of secondary source flow
ripple cancellation was conceptualized, modeled, and implemented in a tandem
axial-piston unit. The strategy consists of setting the phase between the two
synchronous units to accomplish destructive interference in targeted unit
harmonics. Two indexing strategies are investigated first analytically and then
on simulation. One of the indexing strategies was implemented in a pre-existent
commercial axial-piston tandem unit.
Experiment results confirmed effectiveness for the first and third
unit’s harmonics, where reductions over 15dB on pressure ripple were measured.</p>
<p> </p>
<p>Finally,
a fluid-structure interaction based on the poison coupling principle is
developed using the method of characteristics. Transfer functions of the
pipeline accelerations versus the pressure ripples on lines calculated on
simulation and later obtained experimentally to highlight ta critical vibration
band from 2000Hz to 3000Hz with high acceleration response.</p>
<p> </p><br>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/13356725 |
| Date | 14 December 2020 |
| Creators | Leandro Henschel Danes (9750938) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/COMPUTATIONAL_METHODS_FOR_DESIGNING_NEW_PASSIVE_FLUID_BORNE_NOISE_SOURCE_REDUCTION_STRATEGIES_IN_HYDRAULIC_SYSTEMS/13356725 |
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