Office for Technology Commercialization

Bulk Modulus and Density of Moving Fluid Sensor

Technology #20160373

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James Van de Ven, PhD
Associate Professor, Mechanical Engineering
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Managed By
Kevin Nickels
Technology Licensing Officer 612-625-7289
Patent Protection

Provisional Patent Application Filed

Pressure Wave Velocity Indicated Bulk Modulus and Density

A new pressure sensor can determine the density and bulk modulus of a moving fluid by measuring the sonic velocity in two separate pipes. As fluid moves through pipes of differing wall thicknesses and/or different materials, the time it takes a pressure wave to travel through the pipes can be measured. The measurements and corresponding relationships can then be used to calculate the density and bulk modulus. An inline sensor comprised of two segments of pipe with different physical characteristics and three pressure sensors measure pressure wave velocity. This framework, which is highly scalable, can be used in industrial and hydraulic applications. It offers improved efficiency and predictive/precision control.

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Hydraulic System Performance Measurement

Density and bulk modulus of a fluid are important properties to hydraulic system performance that can change dynamically. Accurate measurement is important for predictive control and high operational efficiency. While bulk modulus and density can currently be measured for a fixed volume of non-moving fluid, there is no way to accurately measure these properties for a moving fluid in a hydraulic system. Instead, current systems rely on assumptions, often inaccurate, which adversely affect performance. The equations used in this technology calculate bulk modulus and density of flowing fluid, which improves efficiency by about 5-7%, and improves predictive/precision control.


  • Calculates bulk modulus and density of flowing fluid
  • Improved efficiency (~5-7% in efficiency lost using prior art techniques)
  • Improved predictive/precision control
  • Pipes of different thickness and material provide variables for comparing fluid flow
  • Sonic wave creation facilitates sonic velocity measurement
  • Real time measurement
  • Wide range of fluids used in varying applications
  • Sensor collects and transmits data


  • Hydraulics
  • Fluid systems
  • Pressure sensors

Phase of Development - Concept