Effect of Throttle Output Pressure on Discharge Coefficients

We conducted experimental and analytical studies of fluid flow through throttles and plotted the throttle discharge coefficient as functions of back pressure and the Reynolds number Re for the case of the operating fluid flowing through a closed duct. The investigation shows that the fluid behaviour and discharge coefficient depend on the flow pattern and the pressure at the point where the flow exits the local friction throttle. It is possible to use the resulting analytical expression µ = f (Re, р_out) in practice to compute parameters of dynamic processes for hydraulic devices operating in the range of 4000 < Re < 16 000, when the expected error is up to ± 0,5 %. We show that a technical specification for hydraulic devices should include and support the stipulated boost pressure, which is required for validating parameters at specific points on the throttle operation characteristic

References

[1] Altshul A.D. Gidravlicheskie soprotivleniya [Hydraulic resistance]. Moscow, Nedra Publ., 1982. 224 p.

[2] Fomichev V.M. Engineering characteristics of control valve in "zero" region. Gidravlika i pnevmatika, 2005, no. 20, pp. 49–54 (in Russ.).

[3] Labuntsov D.A., Yagov V.V. Mekhanika dvukhfaznykh system [Mechanics of two-phase systems]. Moscow, Izd-vo MEI, 2000 Publ. 374 p.

[4] Aleksandrov A.A., Orlov K.A., Ochkov V.S. Teplofizicheskie svoystva rabochikh veshchestv teploenergetiki [Thermophysical properties of working medium for heat power engineering]. Moscow, Izd-vo MEI Publ., 2009. 224 p.

[5] Prokofev V.N., ed. Aksialno-porshnevoy reguliruemyy gidroprivod [Axial-piston hydraulic adjustable drive]. Moscow, Mashinostroenie Publ., 1969. 496 p.

[6] Nikitin O.F. Rabochie zhidkosti i uplotnitelnye ustroystva gidroprivodov [Working fluids and sealing devices of hydro drives]. Moscow, Bauman MSTU Publ., 2013. 284 p.

[7] Nikitin O.F. Behavior of the flow with backpressure. Inzhenernyy zhurnal: nauka i innovatsii [Engineering Journal: Science and Innovation], 2013, no. 4 (16) (in Russ.). DOI: 10.18698/2308-6033-2013-4-691

[8] Nikitin O.F. Gidravlika i gidropnevmoprivod [Hydraulics and hydraulic drive]. Moscow, Bauman MSTU Publ., 2012. 430 p.

[9] Chuprakov Yu.I. Gidroprivod i sredstva gidroavtomatiki [Hydraulic drive and hydro-automatics]. Moscow, Mashinostroenie Publ., 1979. 232 p.

[10] Nekrasov B.B. Gidravlika i ee primenenie na letatelnykh apparatakh [Hydraulics and its application in aircraft]. Moscow, Mashinostroenie Publ., 1967. 368 p.

[11] Khokhlov V.A. Gidravlicheskie usiliteli moshchnosti [Hydraulic power amplifier]. Moscow, Izd-vo AN SSSR Publ., 1961. 104 p.

[12] Blackburn J.F., Reethof G., Shearer J.L., eds. Fluid power control. MIT Press, 1960, 710 p.