MSC Software Corporation：Modeling and Simulation of Fluid Power Systems Using MSC.EASY5

MSC Software MSCEASY5 The Transient Form of Momentum Conservation More exactly models processes in hydraulic components, especially long pipes Adds more states(increases complexity Introduces very lightly damped eigenvalues from coupling in P and w (second-order response Pipes are modeled as multi-sectioned, with individual pressure and flow-rate states in each section EAS103 Fluid Power Systems Advanced Class-Chart 16

MSC.Software EAS103 Fluid Power Systems Advanced Class - Chart 16 MSC.EASY5TM The Transient Form of Momentum Conservation • More exactly models processes in hydraulic components, especially long pipes • Adds more states (increases complexity) • Introduces very lightly damped eigenvalues from coupling in P and w (second-order response) • Pipes are modeled as multi-sectioned, with individual pressure and flow-rate states in each section

MSC Software MSCEASY5 Computational Implications of choice of Momentum Model Transient form Large number of states(expensive computation) Low damping, poorer performance with Gear algorithms Steady-state form Very stiff systems with non-physically high frequencies Ideal for Gear integration Note: Volumes for indiv idual components may sometimes be increased to improve computational performance P in out increasing V reduces eigenvalue EAS103 Fluid Power Systems Advanced Class-Chart 17

MSC.Software EAS103 Fluid Power Systems Advanced Class - Chart 17 MSC.EASY5TM Computational Implications of Choice of Momentum Model • Transient form – Large number of states (expensive computation) – Low damping, poorer performance with Gear algorithms • Steady- state form – Very stiff systems with non-physically high frequencies – Ideal for Gear integration Note: Volumes for individual components may sometimes be increased to improve computational performance. P ·  V --- Qi n Qout V · = ( ) – – increasing V reduces eigenvalue

MSC Software MSCEASY5 Orifice Flow Turbulent turbid TDh paPI Sgn(△P) 兀 pD, Cd(△P) Laminar lam puRe Rer is the reynolds number where transition occurs EAS103 Fluid Power Systems Advanced Class-Chart 18

MSC.Software EAS103 Fluid Power Systems Advanced Class - Chart 18 MSC.EASY5TM Orifice Flow Turbulent wturb Cd Dh 2 4 =  ----------- 2 DP  sgn( ) DP Laminar wlam  Dh 3 Cd 2 ( ) DP 2R eT = ---------------------------------- ReT is the Reynolds number where transition occurs

MSC Software MSC,EASY5 Switch State Representation of Orifice Flow Regimes SWQ=2:…SWQ=1…:SWQ=2 Re R Reynolds num ber not laminar <..laminar not laminar EAS103 Fluid Power Systems Advanced Class-Chart 19

MSC.Software EAS103 Fluid Power Systems Advanced Class - Chart 19 MSC.EASY5TM Switch State Representation of Orifice Flow Regimes Q 0 Reynolds Number SWQ = -2 SWQ = 1 SWQ = 2 not laminar laminar -ReT ReT not laminar

MSC Software MSCEASY5 Pipe Model Use correct type of pipe Adiabatic or non-adiabatic Storage/Resistive or Resistive Momentum transfer ignored or considered Flexible walls 20D Roughness modeled or smooth walls: f △P (XI + L)w EAS103 Fluid Power Systems Advanced Class-Chart 20

MSC.Software EAS103 Fluid Power Systems Advanced Class - Chart 20 MSC.EASY5TM • Use correct type of pipe – Adiabatic or non-adiabatic – Storage/Resistive or Resistive – Momentum transfer ignored or considered – Flexible walls – Roughness modeled or smooth walls: Pipe Model f 2Dh XL ( ) + L ---------------------- A w ---    2 =  DP