Fw: http://paulin.com/BosFluids.aspx Re: [PipingDesign] Water Hammer Force in CAESAR Model
glbmail.com
From: Raymond <raymond....@ziggo.nl>
To: Piping...@yahoogroups.com
Sent: Wed, 16 February, 2011 1:39:13 PM
Subject: http://paulin.com/BosFluids.aspx Re: [PipingDesign] Water Hammer Force in CAESAR Model
If anybody needs some more information about Bos fluids see link below:
http://www.dynaflow.com/fileadmin/images/consulting/The_theory_behind_BO\
Sfluids_revA.pdf
Kind regards,
Raymond MetselaarPDMS Piping designerAberdeen, UK
--- In Piping...@yahoogroups.com, "leonard thill" <lsthill@...>
wrote:
>
>
> What is BOS Fluids? http://paulin.com/BosFluids.aspx
>
> BOS Fluids is the engineering software package that analyzes fluid
transients
> in pipe systems and relates this information back to the mechanical
piping
> system transferring the
fluid.
>
> For years piping engineers have labored with simplifying hand methods,
> cumbersome analog computers, or user-unfriendly software products when
needing
> basic steady state and transient fluid analysis capability. BOS Fluids
was
> written specifically to address the need of the piping engineer for
fluid
> reaction forces, and to provide a system whereby the fluid simulation
results
> can be easily integrated back into the piping system design and
analysis.
>
> BOS Fluids is an interactive computer simulation package that models
steady
> state and transient flow in liquid or gas carrying piping systems. The
> procedure is easy to use and interfaces with most pipe stress
programs. The
> package contains the elements required to model most common unsteady
flow
> conditions. The elements included in the simulation package are
pipes,
valves,
> pressure relief valves, vacuum breaker, air valves, pumps, equipment,
surge
> vessels, inlets, outlets, and orifices. BOS Fluids makes fluid
simulation
> simple and easily accessible and yet gives the analyst pressure
transients and
> dynamic force results with an engineering accuracy.
>
> Based on a number of realistic assumptions a simplified form of the
time
> dependent conservation (Navier-Stokes) equations are solved for the
internal
> channel flow. The assumptions made are listed below.
>
> •Fluid behavior in pipes is one dimensional i.e. similarity of
cross
> sectional distribution of properties does exist.
> •Fluid transport velocity is small compared to wave speed.
> •Wave fronts remain plane while propagating.
> •Gas simulations assume that flow velocities are below sonic,
and that
>
pressure drops through the system are less than 30%.
> Based on these approximations friction effects are lumped. The present
> friction model used is Colebrook-White. The Darcy-Weisbach flow model
is used
> for steady state pressure drop calculations and the basic theory
applied in
> BOS Fluids can be found in Wylie & Streeter's "Fluid Transients"
published by
> FEB Press. BOS Fluids is capable of simulating both the steady and
transient
> behavior of liquid carrying closed conduit systems of pipes, valves,
pumps and
> surge relief devices. The following special features are available.
>
> •Pipe stress models from either CAESAR or PipePak can be
downloaded for
> fluid analysis.
> •The analyst can pick different fluids from a database or add
their own
> fluids to the database.
> •Two different models are available to simulate
column
separation:
> Concentrated Air Pocket (CAP) model and the Vapor Cavity Model (VCM).
> •Various pipe materials can be applied-both isotropic (Metals)
and
> Orthotropic (FRP) materials are included.
> •Based on geometry typical pump properties are generated
automatically.
> •Buried and above ground systems can be simulated.
> •Simultaneously the transient response of multiple sources: Pump
starts,
> Pump Failures, Valve Operations can be simulated.
> •Harmonic option allows an analysis of the occurrence of
standing waves.
> •Maximum and minimum pressures and velocities occurring during
transient
> and/or harmonics are traced.
> •The force processor allows an analyst to survey the time
history of the
> unbalanced forces on pipe sections and preprocesses the force time
histories
> to be used in the dynamical
module of the pipe stress program.
> •A spectrum breakdown of force time histories is available. The
analyst can
> see the natural frequencies of the fluid response that tend to excite
the
> piping system.
> •Metric (SI) and English Units can be selected.
> Typical analyses using BOS Fluids include: water transmission and
distribution
> systems, main cooling water systems for chemical plants, sewage water
systems,
> combined power and drinking water cycle power stations, oil product
transport
> lines, tanker loading and unloading systems and dynamical behavior of
chemical
> liquid transport lines. Acoustic analyses for compressors and pumps.
>
>
> Best Regards
> Stephen
>
> Leonard S. Thill | Senior Mechanical Engineer Static Equipment
Specialist:
> Piping and Vessels Engineer / Piping Stress{TWIC} | Houston, Texas
USA
|
> +1-832-497-1300 | http://www.linkedin.com/in/leonardstephenthill
|SKYPE on my
> iphone |
>
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>
> ------ Original Message ------
> Received: Tue, 15 Feb 2011 11:11:20 AM MST
> From: Christopher Wright chrisw@...
> To: Piping...@yahoogroups.com
> Subject: Re: [PipingDesign] Water Hammer Force in CAESAR Model
>
>
> On Feb 15, 2011, at 10:28 AM, Erik Scheir wrote:
>
> > Transient analysis of the performance of piping systems is often as
> > important as the analysis of the steady state operating conditions
and
> > certainly when a centrifugal pump is involved.
> >
> > The unbalanced pressure between two bends has to be calculated and
> > so the
> > unbalanced force (Dynamic force= dP*A) where dp= unbalanced
> > pressure, A=
> > internal pipe area.
>
> Adding to this is the transient nature of the loading. That's what
> make domestic plumbing bang and shake when you shut off the faucet.
> If you or CAESAR can't
do dynamics it'll be a waste of time trying to
> assess this one.
>
> If you know something about how to visualize piping as a collection
> of simple SDOF systems you might have some luck estimating the
> dynamic amplification of the unbalanced force applied instantaneously
> (usually about 2) at various points and considering the response of
> individual runs, but it'll take some experience to know what to look
> for.
>
> Christopher Wright P.E. |"They couldn't hit an elephant at
> chrisw@... | this distance" (last words of Gen.
> ......................................| John Sedgwick, Spotsylvania
> 1864)
> http://www.skypoint.com/members/chrisw/
>
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