published Sun, February 12, 2012
IDAC performs CFD and structural FEA snalyses on a pump case
Rupert Knowles of Hayward Tyler says: “Working with IDAC has enabled us to complete a complex and detailed analysis which met the design criteria. We have used IDAC on a number of occasions over the last six years, and have always been pleased with the response and performance of IDAC. We have always been confident with the output received from IDAC which gives credibility to our designs.”
The pump casing was made of carbon steel, and the branches of
the pump were connected to pipes. The geometry of the pump-motor
assembly along with the sealing gasket between the pump and motor
was supplied by Hayward Tyler as a single 3D model STEP file.
The pump casing was made of carbon steel, and the branches of
the pump were connected to pipes. The geometry of the pump-motor
assembly along with the sealing gasket between the pump and motor
was supplied by Hayward Tyler as a single 3D model STEP file.
The CFD model was created by importing the 3D geometry into
ANSYS DesignModeler and creating a volume of ambient air around it.
For the FE model, fine details deemed to be inconsequential to the
analysis were removed from the geometry, in order to produce a more
efficient mesh.
The pump inlet and outlet pipes were extended at either end to
ensure an adequate representation of the natural convection flow
around the assembly, and also to accurately capture the axial
stresses in the pipes.
The geometry was meshed with 3D tetrahedral elements for both
the fluid and the structural regions using ANSYS Workbench version
13.0. The graphic to the left shows the mesh used. The areas near
the external air and pump interface were locally refined to obtain
a high density of elements leading to an accurate resolution of the
heat transfer coefficient calculated at the pump walls.
The design temperature of the pump was 370ºC and the design
pressure 211bar. The pump could be subjected to situations when
water (maintained at temperature of 367°C) sat inside the pump for
weeks together. Hence the internal walls of the pump were given a
boundary condition of the water temperature instead of modelling
the water flow through the pump. The objective of the analysis was
to check the stresses on the branches of the pump case at the
design condition. As the pump was located at a place where there
would be just still air around it without any externally driven
(fan) cooling, the external heat loss was only through natural
convection. This was modelled within ANSYS CFX.
Company Profile
Hayward Tyler was established in 1815 and almost 200 years later
their engineering excellence places them at the forefront of
engineered solutions for critical application in Power Generation
and Offshore Oil and Gas Technology.
Their products are custom designed and built to superior
standards, ensuring endurance in demanding conditions.
Hayward Tyler's primary markets are Oil & Gas, Power
Generation, Renewable Energy and Chemical Processing
industries.
Hayward Tyler pumps are installed all over the world. They are
the preferred choice for operators who have to ensure total
reliability and a long life. They supply two thirds of the world's
boiler circulation pumps as they are renowned for their
reliability, often running continuously for years and years,
non-stop. Their pumps are designed to meet the most demanding of
applications.
Background
Hayward Tyler was required by their client to provide a pump casing
which was able to withstand a temperature increase of 56ºC in 3
seconds. The casing was for a 500MW double discharge pump used to
circulate water into a boiler, being used in the power generation
industry.
Hayward Tyler designed a pump for this application and as a part
of the design process required IDAC to carry out Computational
Fluid Dynamic (CFD) analyses and subsequent Finite Element Analyses
(FEA) in order to verify that there would not be any excessive
stresses in the structure due to the thermal stress and the
internal pressure of 211bar.
This required a Fluid Structure Interaction (FSI) solution to be
performed. The ANSYS range of products allows the interaction
between fluids and surrounding structures to be solved. Products
within the ANSYS Suite can be combined to perform one-way and
two-way FSI. For the purpose of this project a one-way FSI solution
was carried out. ANSYS CFX was used to carry out the fluid/thermal
analysis and this was followed by an FEA analysis carried out in
ANSYS/Mechanical in order to obtain an accurate stress
solution.
Date: 12/02/2012