This pressure regulator model is part of amulti-component digital prototype where Blue Ridge Numeric’s CFdesign was used to evaluate system performance during the early engineering phase of a firefighting pumper truck. The tank, pump, pressure regulator, flow control valve, and nozzle were included in the simulation, illustrating a wide range of applications ideally suited for first-pass CFD. Image courtesy Blue Ridge Numerics.
Turbulent water, cooling air, viscous oil, liquid plastic — regardless of its specific type, the impact of fluid flow on successful part or assembly performance can range from modest to critical. Many mechanical engineers come to this analysis task with minimal experience, yet need to make quick decisions about heading down the “best” design path before spending a large portion of the design cycle on refinements.
How are today’s engineers honing in on these first-pass, upfront evaluations? They’re doing it with computational fluid dynamics (CFD) software that pays crisp attention to their operational needs.
The driving factor seems to be ease-of-use, defined by a short learning curve, intuitive user operations, and clear tutorial examples. Flexibility in changing parameters for quick, multiple what-if runs ranks next, and third is some level of automation. Lastly, good support through phone or online help is crucial; the latter particularly so because many users fall into the occasional-use category.
Products that often come to mind for upfront CFD include STAR-Works from CD-adapco, EFD.Pro from Flomerics, CFdesign from Blue Ridge Numerics, COSMOSFlow from SolidWorks, and FloWizard from ANSYS/Fluent. However, many users find equal success with such classics as CFX from ANSYS, 3D-Fluid from Cranes Software, PowerFLOW from Exa, Flow3D from Flow Science, Algor from Algor, NX Flow from Siemens PLM, COMSOL from COMSOL, PHOENICS from Concentration Heat and Momentum Ltd (CHAM), and PORFLOW from ACRi — the list goes on (for an extensive CFD listing and directory click here.
DE asked several CFD software customers about their design challenges and the solutions they’ve found. We asked what made their choice effective for them, how it fit into the general design process, and what might make the software even better.
Bronswerk Heat Transfer BV uses EFD.Pro from Flomerics to model airflow through heat exchangers, condensers, blowers, and compressors. The company is expanding use of the software beyond R&D into main stream engineering design throughout the enterprise. Image courtesy Bronswerk Heat Transfer BV.
A Fundamental Change
Bronswerk Heat Transfer BV is a Netherlands-based manufacturer of heat exchangers, condensers, heaters, blowers, compressors, and fans, whose products are used in the pharmaceutical, process, and oil and gas industries. The company uses the EFD.Pro CFD analysis package from Flomerics, Inc., embedded in Pro/ENGINEER Wildfire design software, to understand flow and heat transfer in its products.
Last year, EFD.Pro was instrumental in the company’s design and verification of a series of groundbreaking air-cooled coolers and fans. Having seen the successful use of CFD technology in its R&D department, Bronswerk was keen to expand its use. “It is very important to us to use EFD.Pro on a more regular basis,” says Johan van der Kamp, chief design engineer for Bronswerk. “But we are not analysis specialists and we do not know the full potential of what the technology can do for us.”
To ensure that the process would work across a range of users, Bronswerk asked Willert Boevee and Bas Bovenkamp, two undergraduate students at the nearby Windesheim School of Engineering and Design, to become familiar with the software. The students began work on several examples of tube-type heat exchangers. “Tubes are deceptively simple-looking on the surface,” remarks Boevee. “However, flow-through tube bundles can be very complex as the fluid may experience both laminar and turbulent regimes. When you add heat transfer to the equation, then the problem becomes even more complex.”
Boevee and Bovenkamp found that EFD.Pro let them readily create a series of visualization plots. The former comments, “So far we have found EFD.Pro quite easy. You don’t need to be an expert at CFD…. It’s a great insight when you are able to see under which conditions the flow changes or when laminar flow becomes turbulent and how quickly.” As a byproduct of the research, the students have created a how-to manual for Bronswerk’s engineering team. Van der Kamp says the manual will help his company’s designers use the software to its full potential beyond R&D.
Tough Truck, Easy Software
Not everyone gets to focus on CFD day in and day out. Kevin Pennau, a senior design engineer in Oshkosh Trucks’ Advanced Products Group, must be a jack-of-all-trades, serving as an in-house mechanical consultant for engineers throughout his company. Oshkosh Trucks’ wide range of products includes military vehicles, fire-pumpers and tankers, concrete mixers, refuse-haulers, heavy-duty tow-trucks, and aerial-access equipment.
Depending on the project, Pennau handles general design, static and dynamic finite element analyses, motion simulation, and fluid analysis. Specific CFD challenges have included looking at airflow over vehicles for improving fuel economy and designing thermal heat sinks for electronics cooling. He’s even had to figure out why the sunscreen on a new vehicle would rip off only when being transported on a flatbed truck. Three years ago he was tasked with finding a cost-effective CFD package to handle the ongoing variety of issues, and chose CFdesign for CATIA from Blue Ridge Numerics (BRNI).
“I saw a demonstration where they walked you through a couple of analysis examples,” explains Pennau of his purchase decision. “I was amazed at how straightforward it was, how easy to use. One thing that really caught me was the flexibility with units. It does all the conversions for you, so there’s never a question.”
He has done quite a few flow analyses of water pumping through a fire-tanker system, quantifying pressure drops, avoiding eddy currents at inlets, and easing pump cavitation problems. For these and other aspects of the 350 or more analyses he figures he has now done using CFdesign, Pennau has been able to work with what he learned in a two-day basic training class, a one-day advanced course a year later, and regular use of the well-staffed BRNI help line.
The Oshkosh Trucks engineer says the ease-of-use is by far the driving factor for his software success. He feels that someone with a decent understanding of heat transfer and fluid flow can start using CFdesign and get good results after a week or so — not a bad return on investment. In fact, the process is so handy, Pennau says, “If someone comes to me with a flow problem, I tell them, why would you work with your fluid-flow book and three pages of calculations, when I can get you good resolution and results in a few hours or by tomorrow morning? For me, it’s as second nature as a calculator, only for CFD work.”
Part 2 of this look at early design phase CFD will discuss further examples of how users save time and money by narrowing their choices early in the product development process.
Bel Air, CA
Altair Engineering, Inc.
Blue Ridge Numerics Inc. (BRNI)
Concentration Heat and
Momentum (CHAM) Ltd.
Flow Science Inc.
Santa Fe, NM
Siemens PLM Software
Contributing Editor Pamela J. Waterman is an electrical engineer and freelance technical writer based in Arizona. You can contact her about this article via e-mail sent to DE-Editors@deskeng.com.