[LDi] Liquid Dynamics International Liquid Dynamics International Inc. Click here to: Contact Liquid Dynamics Liquid Dynamics offers pulsation, vibration, and shock analysis, diagnostics, and software models. Fluid Flow Control Animations
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MODELING
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ShockView schematic

ShockView plots A, B, C

Input data for shock modeling

PulseView models relations

7 ocillographic plots

Necess. program input data

Equations& sources

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Predict valve, membrane, & liquid mass motion, responses to flow from reciprocating pump action, to generate the pressure pulsation.
Ex: Initial choice, outline of equations, for compiling a fortran "dt" iterativeLDi shock analysis software display for motions & resultant pressure pulsation.

Note, in this primitive skeletal outline example of LDi method, position numbers: D, G, L, P, & V, 00, 01, 02, 03, 04, etc. are aspg. 29.

Symbols - Img 1Symbols - Img 2Symbols - Img 3Symbols - Img 4

Assumption in this example are: That there is no vortex or other instability at system inlet, and that the system load, is not applied by a "spill back loop" or a "controller" that "modulates" open and closed.

1.
Constant
Suction Source, Load
Ref.
2.
Number 2
Suction Manifold Inlet Flow
A
3.
Number 3
Suction Manifold Outlet Flow
A
4.
Number 4
Suction Manifold Pressure Balance
B
5.
Number 5
Suction Check Inlet Mass Flow
A
6.
Number 6
Suction Check Pocket Flow Balance
B
7.
Number 7
Suction Check Motion
C
8.
Number 8
Piston Position
A
9.
Number 9
V11 Flow Balance
B
10.
Number 10
V11 Volume Change
 
11.
Constant
Load
 
12.
Number 12
Discharge Check Inlet Mass Flow
A
13.
Number 13
Discharge Check Motion
C
14.
Number 14
Discharge Check Pocket Flow Balance
B
15.
Number 15
Discharge Check Outlet Mass Flow
A
16.
Number 16
Discharge Manifold Pressure Balance
B
17.
Number 17
Discharge Manifold Outlet Mass Flow
A

References: A. Pump Handbook, 2nd Ed. Karassik eq 38., p.3.8. B. Mechanics of Fluids, 6th Ed. Massey eq 13.14 & 13.16 C. Handbook of Noise & Vibration, 6th Ed. Barber, M.I.T. 1960 Library of Congress Cat Card Nbr 59-6759 E&OEE

Whilst LDi PulseView software also displays "acoustics", it is primarily a mass, motion, & pressure model - not an attempt to determine them from "acoustic" frequencies and amplitudes.

 

Y & Z – Valve position, m Nfr – Coulomb friction force, N F – Area meters squared m2 Cfr – Viscous friction coefficient, N sec/m p – Density, kg/m3 P – Pressure, Pa G – Mass flow, Kg/sec Cspr – Spring rating, N/m w – Angular velocity, 1/radius R – Crankshaft radius, m l – L/F – Fluid column inertia, 1/m D – Diameter, m In these descriptions: N – Newtons, m – meters, Pa - Pascals X – Piston position, m T – Time, sec m – Mass, Kg L – Length, m E – Bulk modulus of liquid, Pa
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