In-Situ Measurement of the Wavespeed and Bulk Modulus in Hydraulic Lines

The dynamic performance of a hydraulic system is dependent on the fluid bulk modulus, which can be affected by several factors including air release and pipe compliance. A technique is described for the in situ measurement of the speed of sound from which the bulk modulus may be evaluated. It entails analysis of pressure ripple recorded at three locations in the hydraulic line. Measured values of the bulk modulus in high-pressure pipes were found to be close to the isentropic tangent bulk modulus predicted from the fluid manufacturer's data.

[1]  D N Johnston,et al.  The Impedance Characteristics of Fluid Power Components: Relief Valves and Accumulators , 1991 .

[2]  D N Johnston,et al.  The Impedance Characteristics of Fluid Power Components: Restrictor and Flow Control Valves , 1991 .

[3]  I Potts,et al.  An Undergraduate Introductory Course on Computational Fluid Dynamics , 1991 .

[4]  D N Johnston,et al.  The ‘Secondary Source’ Method for the Measurement of Pump Pressure Ripple Characteristics Part 1: Description of Method , 1990 .

[5]  K A Edge,et al.  The ‘Secondary Source’ Method for the Measurement of Pump Pressure Ripple Characteristics Part 2: Experimental Results , 1990 .

[6]  Peter N. Nikiforuk,et al.  Design of an Electrohydraulic Positioning System Using a Novel Model Reference Control Scheme , 1989 .

[7]  K. A. Edge,et al.  The use of plane wave theo ry in the modelling of pressure ripples in hydraulic systems , 1983 .

[8]  F. T. Brown,et al.  Measurement of the Propagation of Long-Wavelength Disturbances Through Turbulent Flow in Tubes , 1975 .

[9]  J. Funk,et al.  A Boundary-Layer Theory for Transient Viscous Losses in Turbulent Flow , 1970 .

[10]  W. Zielke Frequency dependent friction in transient pipe flow , 1968 .

[11]  D. M. Ellis,et al.  Applied Regression Analysis , 1968 .

[12]  E. E. Klaus,et al.  Precise Measurement and Prediction of Bulk-Modulus Values for Fluids and Lubricants , 1964 .

[13]  G. A. Parker,et al.  Transmission of Power by Sinusoidal Wave Motion through Hydraulic Oil in a Uniform Pipe , 1964 .

[14]  D. Mcmillan,et al.  A Precision Ultrasonic Interferometer for Liquids and some Velocities in Heavy Water , 1947 .

[15]  M. Hashimoto,et al.  Unstable vibration occurring in a hydraulic servomechanism controlled by a throttle valve. II, Measurement of dynamic axial force and theoretical considerations , 1989 .

[16]  G. Schoenau,et al.  Lumped parameter model of a variable displacement pump , 1988 .

[17]  K. Suzuki,et al.  A hydraulic pressure intensifier using oil hammer and its application to a hydraulic cylinder , 1988 .

[18]  A. Hayward How to estimate the bulk modulus of hydraulic fluids , 1970 .