Pulsation analysis services

In fluid systems, pressure pulsations may occur due to periodical excitation, transient flow conditions, or vortices excited at piping junctions and obstructions. Flow-induced vibration, or vortex shedding, may lead to mechanical resonance and excessive pressure variations that, if uncontrolled, may cause piping systems failures and unacceptable noise levels for occupation.

Objectives

Flow-induced vibration (FIV), or vortex shedding, may be either self-induced, i.e. due to piping obstructions and T-junctions, or forced, i.e. generated by machinery such as reciprocating compressors and pumps. At specific frequencies, flow pulsations excite acoustic resonances, producing high pressure pulsations that may excite mechanical resonances, produce high vibrations, or cause fatigue failure.

S.A.T.E. S.r.l. provides consultancy services for dynamic simulations of pressure pulsation in fluid plants, due to reciprocating machines, rotary compressors, axial and centrifugal turbomachinery, and vorticity in piping diffusers, dead branches, or junctions, with the scope of allowing design engineers and operators to control FIV and the corresponding physical parameters.

Software suite

The solutions proposed allow to investigate the acoustic and mechanical response of a fluid plant interacting with machinery and to identify remedy actions to control or limit vortex shedding effects, exploiting the proprietary software suites:

  • ACUSYS®: Simulation of pressure pulsation in fluid plants, by interaction with reciprocating machines or self-excited vortex flows;
  • ACUSCOMP™: Dynamic simulator of reciprocating compressors interacting with piping flow and pressure dynamics;
  • MECHDYN™: Complete static and dynamic analysis of beam-like mechanical structures;
  • HYDRODYN™: Dynamic simulator of single-phase flow in piping and plants for seals barrier fluid analysis, suitable for turbulent low subsonic flow conditions.

Benefits

A synthetic approach

ACUSYS® helps preventing unwanted FIV, by providing designers with quantitative and qualitative information to complete the plant’s analysis and define suitable acoustic filters, piping modifications, and stiffeners

Time-saving

ACUSYS® is a cost-effective alternative to the trial and error approach used in the definition of size and position of pressure pulsation dampers

Reliability

ACUSYS® allows the user to rely on a fully qualified suite, as it has been deeply tested and validated against existing commercial CFD codes, showing excellent results

Machine piping interaction

By time domain non-linear modelling of a piping system, ACUSCOMP™ helps analysing the interaction between machine thermodynamics, valves mechanics, and fluid exchange processes considering also flow dynamics

Mechanical analysis

For beam-like mechanical structures, MECHDYN™ allows to perform static and dynamic analysis, calculating the natural frequencies, vibrating modes, transfer functions, and displacement and velocity response to periodic inputs

Features

ACUSYS – Simulation domains

ACUSYS® simulates, in the frequency and time domains, the dynamic response of the fluid medium in a plant, either liquid, gas, or dispersed bi-phase

Simulation capabilities

ACUSYS® provides acoustic pressure, flow rate, and shaking forces at piping joints and bends as response to multiple stationary inputs. It also simulates hydraulic systems transients, verifying water hammer effects

Descrete-elements based

In ACUSYS®, the plant is described by discrete elements, following the linear electro-acoustic equivalence, with the possibility of including in the model also non-linear components or propagation equations

Automatic model generation

ACUSYS® can automatically generate a plant model from an input data file, resulting into high time savings

ACUSCOMP – Simulation domains

ACUSCOMP™ simulates the time-domain dynamic response of the gas me­dium in a plant, described by piping state space matrices, single or double effect cylinders, plena, and valves and restrictions

MECHDYN – Simulation domains

MECHDYN™ carries out the mechanical analysis of piping systems investigated with ACUSYS®, providing their natural frequencies and vibrating modes, in order to verify their separation from acoustic resonant pulsations

System Architecture

Typical workflow for the pulsation analysis process:

  1. ACUSCOMP™ simulates, in the time domain, the dynamic response of the gas me­dium in a plant, including:
    • The overall dynamic characteristics of the piping sides connected to the cylinders (described by piping state space matrices, preliminarily calculated by ACUSYS®).
    • Single/double effect cylinders with:

      • Suction and discharge valve dynamics between the cylinders and plant sides
      • Cylinder thermodynamics, including both the open and closed phases
      • Leakages through piston and rod seals
    • Plena, i.e. buffer volumes between machines, valves, and piping
    • Valves and restrictions, i.e. equivalent pressure losses
  2. ACUSYS® studies the linear response of the piping system to the disturbance signals generated at the interface with the gas flow, as determined by ACUSCOMP™, allowing the transfer function and forces analysis in the frequency
    and time domain.
  3. MECHDYN™ performs the complete static and dynamic analysis of the piping mechanical structures.