Mention “energy conservation” to makers of industrial pumps and the words will either strike fear or spell opportunity.
Firmly in the opportunity camp is Finish Thompson, a designer and manufacturer of chemical process, drum and barrel pumps based in Erie, PA. Finish Thompson used CFdesign up-front CFD software to double the efficiency of its new line of DB series of magnetic drive pumps. As a result, the company’s pumps can save customers thousands of kilowatt-hours per year on electric bills. Internally, use of up-front CFD reduced total product development time for the DB series by an estimated 33 percent and cut testing time from months to weeks.
New Path to Efficiency
Efficiency has always been a key market differentiator for Finish Thompson. In the past, arriving at the most efficient design meant waves of physical testing in an effort to maximize flow rate and differential pressure, while minimizing input power. At the end, there was always the feeling that there could have been greater efficiency gains, if only designers could see what was going on inside the pump.
A couple of years ago, plans to redesign the DB series led Finish Thompson’s Engineering Manager Dan Roll and Design Engineer Chad Best on a search to find how they could incorporate CFD into their product development process.
Neither Roll nor Best had CFD experience or the desire to become specialists in that area. Their roles were clear: to design and engineer great products. Hiring a CFD specialist and buying specialized software that worked outside of their proven CAD processes was also not an option.
“We wanted to spend our time doing design, not becoming CFD specialists,” says Roll. Finish Thompson needed “a tool to make a product,” he says. He didn’t want to take on a whole new discipline that would add more layers of complexity to the design process.
After intense evaluation of three or four product providers, Roll and Best decided on CFdesign software from Blue Ridge Numerics.
CFdesign differs from traditional CFD systems in that it works directly with the native geometry of the CAD software used to create the product model. This eliminates the time-consuming process of translating CAD geometry to fit the parameters of the CFD software. Engineers gain insight into pump performance early in the product design process, cutting development time and substantially reducing the amount of physical prototyping and testing required.
Getting the Model Right
The first step for Finish Thompson was arriving at a model that would meet their needs and maximize the benefits of CFdesign. Best started by running simulations of existing products created in SolidWorks. He found he could reduce computing time by eliminating parts of the model he felt were not critical for efficiency testing.
“We found that the simplified models gave us similar results to the full models, but were much faster to run and much easier to set up,” says Best. Most importantly, the CFdesign results for existing products matched those from physical lab tests.
Armed with this information, Roll and Best compiled a list of design parameters for the new DB series pump. An impeller and housing were designed in SolidWorks. Small clearances and non-essential geometry were removed to provide a model that was still accurate for the results the design team wanted to achieve, but would run much faster than a fully detailed model.
The initial design was brought into CFdesign, tested and evaluated based on the team’s desired results. Using pressure and both relative and absolute velocity results, Roll and Best evaluated vane angles of the impeller, both at the entrance and exit, as well as the diffusion in the discharge of the pump. They also evaluated different numbers of vanes and the meridional profile — flow measurements taken parallel to a line of longitude — of the impeller. They checked for separation of the fluid from the vane and any turbulent flow areas that would reduce the pump’s performance.
“One of the most significant benefits of this simulation was being able to change vane angles and see how they interacted with the fluid in both the eye of the impeller and the impeller exit at various flows,” says Best. “This is difficult to see during physical testing.”
From Six Months to Six Weeks
Based on results from simulations, Roll and Best made alterations such as adjusting vane angles, width and thickness; changing the impeller diameter; and manipulating the housing diffusion angle. After changing one item, they reevaluated results and compared them with previous runs. A new simulation could be generated in about 24 hours, as opposed to the three or four days it took previously to make an adjustment to a physical prototype and run new tests.
Best estimates Finish Thompson ran approximately 20 simulations between the DB11 and DB15 series before he and Roll felt comfortable with the design for each model. It would have taken at least twice as many physical tests to come close to these results, according to Roll, and even then the results would not be as reliable, since design engineers would be unable to visualize exactly what was happening inside the pump.
“We were able to do in six weeks using CFdesign what would have taken about six months to do in the lab for the equivalent amount of testing,” says Roll. “We were also able to do a much better job of optimizing our design than we would have been able to do with physical testing. Being able to view the flow within the impeller let us change the vane angles and make other alterations that would have been very difficult to decide upon based on lab results.”
After arriving at the final designs within CFdesign, Finish Thompson developed part drawings and made manufacturing molds for the new DB series. The first sample parts from the molds were tested and performance was approximately six to 10 percent higher than the CFdesign results had predicted.
“We were very pleased with these results,” says Roll, “and confident to move ahead with production.”
Doing More, Better and Faster
While customers are already benefiting from double the efficiency — 35 to 70 percent — in the DB series, Finish Thompson is reaping the rewards of being able to test many more design elements about three times as fast as within a lab environment.
“We estimate that we cut about six months off of our total product development cycle,” says Roll — “from a year and a half to a year.”
After implementing up-front CFD for the first time, Finish Thompson sees a wealth of future possibilities. The company is rapidly expanding its DB series and also has plans to introduce a self-priming pump that customers are already anxious to buy.
“We see great potential in using up-front CFD to help us open up new markets and rapidly expand and continuously improve our product lines,” says Roll.
While other companies anticipate customers’ demands for greater energy efficiency with a dread commonly reserved for taxes and the grim reaper, Finish Thompson is exhorting the marketplace to “bring it on.”