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10 Piping Design Simulations: Fluid Flow and Stress Analyses

Piping Design

Piping design is essential for a wide range of applications, from Oil & Gas extraction and transportation, refineries, power stations, HVAC, and cooling systems in engines and turbines. To ensure the functionality of piping networks and improve their performance for fluid transportation, process engineers need efficient tools and solutions for piping design and optimization.

How to Begin a Piping Design?

Here are few essential key factors to consider in a piping design process:

  • Establish the optimum pipes diameter to  guarantee optimum fluid flows for the pipeline system, depending on the specific fluid transportation needs;
  • Establish maximum and working flow pressure and temperatures;
  • Analyzing optimal pipes material composition depending on the chemical fluids properties;
  • Design pipeline network architecture for optimal fluid velocity;
  • Ensure safety factors and quality criteria for the whole pipeline design and pipeline network construction.

Probably the most common engineering problems occurring in any piping design involves the fluid flow behavior and the stress analysis in pipes networks and CFD simulations offer advanced methods to test them.

To easily understand the most important advantages offered by a simulation software let’s review some piping design analyses examples available in the SimScale Public Projects library:

Thermostructural Analysis of a Cracked Pipe

cracked pipe

Increased heat flux on the cracked region.

Due to their extensive use, we have to consider durability and damage tolerance for the whole lifecycle of pipes. Any crack in a pipe can conduct to an important loss of fluid, heat or steam with unpredictable consequences and significant damages costs.

According to Pipeline & Hazardous Materials Safety Administration, in the last 20 years pipeline incidents caused over $6.3 billion in property damages. Statistics shows 250 pipeline incidents per year, with average of 2.5 million barrels spilled. [1]

In this project, the same simulation scenario considers a non-cracked and a cracked pipe also. The CADmodel was created with Onshape and then imported on the SimScale platform. For this analysis, steady state thermostructural was selected since temperature and pressure were considered to be static.

Scalar Transport in T-Junction Pipe

scalar quantity

Contours of scalar quantity in the stream and cross-section planes in the mixing pipe

Experiments on piping design flow show that triggering turbulence depends sensitively on initial conditions. In real life, fluid flow turbulence generates a lot of incidents, especially in the pipeline junction areas. This project simulates Scalar Transport mixing in turbulent T-Junction pipe flow.

This project validates the mixing of a passive scalar quantity in a single phase flow at a Reynolds number of 24900 via the Reynolds-Averaged Navier–Stokes (RANS) approach and K-Omega SST turbulence model. The geometry for this case is a T-Junction pipe with two inlets.

The project simulates the mixing process at the junction and the scalar distribution downstream in the mixing pipe. The shown post-processing image (performed with ParaView) gives the contours of the scalar quantity and the flow field in the vicinity and downstream of the T-junction.

Bending Analysis of an Aluminium Pipe

vonMises stress analysis of a pipe

vonMises stress and total nonlinear strain formed in the bent aluminium pipe.

Structural analysis is frequently used in piping design and simulation process due to the elastoplastic behavior of aluminium or other piping materials. In this project the bending of an aluminium pipe is done via a rolling process.

A nonlinear static structural analysis was selected. The penalty contact with higher stiffness was used for the contact between pipe, roller and molder. The results show the vonMises stress and total nonlinear strain formed in the bent aluminium pipe.

SIM Pipeline Network

pipeline network simulation

Turbulent kinetic energy

The long distance piping networks and junction’s architecture generate a lot of problems for the piping maintenance in oil & gas and industrial water transportation.

This simulation project captures the nuances of turbulent pipe flow. With it, we can visualize the flow phenomena at pipelines bends, junctions and also nozzles. The engineer created the geometry with Salome 7.4.0 and meshed on SimScale using the snappyHexMesh algorithm.

 Non-newtonian Flow of Concrete

In many practical applications, the piping system transports a mix of fluids with different physical properties and different behavior during the flow. One of these applications frequently used in the construction industry are concrete mixes. High slump or “flowing” concrete mixes are economical ready mix products that allow maximum flow without sacrificing strength by adding water at the job site.

Concrete Flow Streamline

This project simulates the flow of a non-Newtonian fluid (concrete) through a pipeline. The mixture mass proportions are: 45% Gravel, 29% Sand, 9% Fine Sand, 17% Cement. The geometry constructed in Salome uses a CAD Model of a ball valve.

The simulation shows the capability of the SimScale platform to model the behavior of non-Newtonian fluids, in this case: concrete.

Comparison of Pipe Junction Designs

In pipeline design projects, engineers need to understand the pipe’s infrastructure behavior in different circumstances. Also, it is efficient to design two or more versions for the same pipe junctions.

pipe junction designs

Here is a good example of two different piping designs, simulated considering their downstream behavior. This project shows also how CFD can help in choosing the best design version. The main difference between the two models is the way the small pipe connects to the main pipe at the junction. Version 1 is a simple connection of both pipes. In version 2, the small pipe continues into the larger pipe and opens up in the middle of the larger pipe.

For this project, the engineer chose an incompressible, steady-state simulation setup applying a k-Omega SST turbulence model. The same simulation setup is used for both versions. If this model is used in the mixed flow of two fluids with very similar physical characteristics, the pipeline engineer will finally choose the version 1, for better efficiency. The simulation of both junction models has also the main advantage to provide an immediate feedback on the performance. In this way, the design process is significantly fast forward.

Pipe Hollow Drawing

ss46-7This project demonstrates a simple simulation of a hollow manufacturing process. The simulation uses the nonlinear static stress analysis method.

Performed on a 8-core machine processes, the whole simulation took less than 2 hours.

The project also allows analysis of the stress field that results from the manufacturing process.

 

Aerodynamics of a Pipe with Vent Holes

Aerodynamics analyses are common across many industries. Even in the healthcare equipment industry, product engineers should simulate the flow aerodynamics inside different medical equipment.

SimScale Project DesignThis project shows first of all how we can analyse the internal airflow through a medical device. For it, a fixed volume flux was applied at the inlet and a zero-gradient boundary condition at the outlet. A k-omega-SST model is also used to account for turbulence effects. Finally the steady-state simulation needed around 320 iterations to reach satisfying convergence criteria which took around 30 minutes on a 4-core machine. This kind of simulations results can be also used to optimize the design in terms of the velocity peaks and the pressure drop of the device.

Creep Analysis of a Superheater Boiler Pipe

Superheaters increase the thermal efficiency in boilers equipment. They consist of several pipes which take the saturated steam and convert it into supe-heated steam, in order to use it in steam engines, steam reforming, or other processes.

SimScale Pipeline Projects.

von Mises stresses image for a stress relaxing at 100,000 hrs.

Working in a high steam pressure, superheaters material should also resist to industrial higher pressure and temperature for a long period of time.

In this project, the superheater pipe is tested for the high steam pressure and then the stresses relaxed for maximum 100000 hrs. Due to symmetry, simulation considers only part of the pipe.

You can apply the cyclic boundary condition according to symmetry in order to represent the simulation for the whole pipe. The steam pressure of 10 MPa was also applied to the inner surface of a pipe.

Pipe Elbow Joint

In piping design, engineers should combine straight tubular pipes in different configurations and for different tubing sections. The elbow joint is probably one of most common piping fit. Also this is usually installed between two lengths of pipe to allow a change of direction.

SimScale Piping Design

von Mises stress at maximum at the bolt hole

Here is a piping design project based on a static structural analysis and convergence study for a pipe elbow with supports on one flange, force due to pipe weight on other flange and fluid pressure from inside.

The results show the von Mises stress, the vertical displacement, as well as weakest point of the elbow, which turns out to be the joint between fixed flange and elbow body and at the bolt hole.


Ready to perform a simulation by yourself? Create a free SimScale account here.

References:

[1] – Matthew Linnitt, “Average 250 Pipeline Accidents Each Year, Billions Spent on Property Damage”, April 2013, DesmogCanada

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