Abstract
Fluid compressibility has a major influence on the efficiency of switch-mode hydraulic circuits due to the release of energy stored in fluid compression during each switching cycle and the increased flow rate through the high-speed valve during transition events. Multiple models existing in the literature for fluid bulk modulus, the inverse of the compressibility, are reviewed and compared with regards to their applicability to a switch-mode circuit. In this work, a computational model is constructed of the primary energy losses in a generic switch-mode hydraulic circuit with emphasis on losses created by fluid compressibility. The model is used in a computational experiment where the system pressure, switched volume, and fraction of air entrained in the hydraulic fluid are varied through multiple levels. The computational experiments resulted in switch-mode circuit volumetric efficiencies that ranged from 51% to 95%. The dominant energy loss is due to throttling through the ports of the high-speed valve during valve transition events. The throttling losses increase with the fraction of entrained air and the volume of fluid experiencing pressure fluctuations, with a smaller overall influence seen as a result of the system pressure. The results of the computational experiment indicate that to achieve high efficiency in switch-mode hydraulic circuits, it is critical to minimize both the entrained air in the hydraulic fluid and the fluid volume between the high-speed valve and the pump, motor, or actuator. These computational results are compared with experimental results in Part II of this two part paper series.
| Original language | English (US) |
|---|---|
| Article number | 21013 |
| Journal | Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME |
| Volume | 135 |
| Issue number | 2 |
| DOIs | |
| State | Published - Mar 20 2013 |
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Keywords
- bulk modulus
- compressibility modeling
- digital hydraulics
- switch-mode hydraulic circuit
Cite this
On fluid compressibility in switch-mode hydraulic circuits-part I : Modeling and analysis. / Van De Ven, James D.
In: Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME, Vol. 135, No. 2, 21013, 20.03.2013.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - On fluid compressibility in switch-mode hydraulic circuits-part I
T2 - Modeling and analysis
AU - Van De Ven, James D.
PY - 2013/3/20
Y1 - 2013/3/20
N2 - Fluid compressibility has a major influence on the efficiency of switch-mode hydraulic circuits due to the release of energy stored in fluid compression during each switching cycle and the increased flow rate through the high-speed valve during transition events. Multiple models existing in the literature for fluid bulk modulus, the inverse of the compressibility, are reviewed and compared with regards to their applicability to a switch-mode circuit. In this work, a computational model is constructed of the primary energy losses in a generic switch-mode hydraulic circuit with emphasis on losses created by fluid compressibility. The model is used in a computational experiment where the system pressure, switched volume, and fraction of air entrained in the hydraulic fluid are varied through multiple levels. The computational experiments resulted in switch-mode circuit volumetric efficiencies that ranged from 51% to 95%. The dominant energy loss is due to throttling through the ports of the high-speed valve during valve transition events. The throttling losses increase with the fraction of entrained air and the volume of fluid experiencing pressure fluctuations, with a smaller overall influence seen as a result of the system pressure. The results of the computational experiment indicate that to achieve high efficiency in switch-mode hydraulic circuits, it is critical to minimize both the entrained air in the hydraulic fluid and the fluid volume between the high-speed valve and the pump, motor, or actuator. These computational results are compared with experimental results in Part II of this two part paper series.
AB - Fluid compressibility has a major influence on the efficiency of switch-mode hydraulic circuits due to the release of energy stored in fluid compression during each switching cycle and the increased flow rate through the high-speed valve during transition events. Multiple models existing in the literature for fluid bulk modulus, the inverse of the compressibility, are reviewed and compared with regards to their applicability to a switch-mode circuit. In this work, a computational model is constructed of the primary energy losses in a generic switch-mode hydraulic circuit with emphasis on losses created by fluid compressibility. The model is used in a computational experiment where the system pressure, switched volume, and fraction of air entrained in the hydraulic fluid are varied through multiple levels. The computational experiments resulted in switch-mode circuit volumetric efficiencies that ranged from 51% to 95%. The dominant energy loss is due to throttling through the ports of the high-speed valve during valve transition events. The throttling losses increase with the fraction of entrained air and the volume of fluid experiencing pressure fluctuations, with a smaller overall influence seen as a result of the system pressure. The results of the computational experiment indicate that to achieve high efficiency in switch-mode hydraulic circuits, it is critical to minimize both the entrained air in the hydraulic fluid and the fluid volume between the high-speed valve and the pump, motor, or actuator. These computational results are compared with experimental results in Part II of this two part paper series.
KW - bulk modulus
KW - compressibility modeling
KW - digital hydraulics
KW - switch-mode hydraulic circuit
UR - http://www.scopus.com/inward/record.url?scp=84875022527&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84875022527&partnerID=8YFLogxK
U2 - 10.1115/1.4023062
DO - 10.1115/1.4023062
M3 - Article
AN - SCOPUS:84875022527
VL - 135
JO - Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME
JF - Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME
SN - 0022-0434
IS - 2
M1 - 21013
ER -