Delivering State-of-the-Art on Schedule
The new TARDEC Ground Systems Power and Energy Lab will allow the U.S. Army to research, develop and test the next generation of military ground vehicle systems.
By Jarrod J. Hoose, M.SAME, Stephen W. Roberts Jr., and Thomas M. Black
Before the U.S. Army could research and build the next generation of military ground vehicles, a new facility needed to be built. Designers and engineers from industry and the U.S. Army Corps of Engineers (USACE) overcame challenges at seemingly every turn to deliver a one-ofa- kind facility on schedule.
The Ground Systems Power and Energy Lab (GSPEL) was built specifically for the Army’s Tank, Automotive, Research, Development and Engineering Center (TARDEC). Constructed by Walsh Construction Co., with on-site construction management from the USACE Detroit District and overall project management from the USACE Louisville District, the 30,000-ft² facility consists of eight separate laboratories that support and sustain the Army’s combat and tactical ground vehicle systems (see sidebar page 60). Those systems—intended for existing and emerging vehicles—include propulsion, power generation, energy storage, power management, thermal management and air filtration. GSPEL’s location, in the heart of metro Detroit’s automotive and engineering technical communities, makes for a synergistic environment that enhances collaboration.
The seismic mass underneath the Power and Energy Vehicle and Environmental Lab at the GSPEL facility outside Detroit is 80-ft-long, 60-ft-wide and nearly 5-ft-thick. The structure is designed to absorb vibrations from 12 dynamometers inside that are used to measure torque output from vehicle axles.PHOTOS COURTESY TARDEC
Because of the unique nature and the precise specifications demanded by GSPEL’s scientists and engineers, the facility’s design and construction presented multiple challenges—many that required solutions on tight deadlines. These trials started before the first spade of dirt was turned and continued throughout.
GSPEL’s “fast-track” process included 13 design phases, requiring constant planning, coordination and adjustments. Ground was broken on the $47 million design-build project in August 2009. Ribbon cutting took place in April 2012.
AN INSIDE LOOK
The facility’s centerpiece is the Power and Energy Vehicle and Environmental Lab (PEVEL), which boasts an environmental chamber and 12 dynamometers used to measure output torque from vehicle axles. Among its many advancements, the environmental chamber can generate up to 95 percent relative humidity, create wind speeds up to 60-mph, and simulate temperatures from -60°F up to 160°F.
To create additional heat, the chamber is outfitted with a solar simulation capability that generates up to 1,200-W per M², which is equivalent to the worst solar heat on earth. Creating such dramatic temperatures demands huge electrical loads. This capacity, like so much of the facility’s needs, required extensive planning. In fact, there was very little “offthe- shelf ” design for the environmental chamber. Components were custom-designed and custom-built. But the lab is capable of accurately mimicking extremely demanding field test conditions in a controlled environment. So by consolidating ground environmental testing at a single location the logistical burden is greatly reduced, which, in the long run, will end up saving time and money.
TARDEC had awarded a contract for the PEVEL dynamometers prior to contract award for the overall GSPEL facility, knowing that the design of the machines would be a lengthy process. The manufacturer then provided 50 percent design drawings at the time of the GSPEL contract award. Immediately, however, engineers knew they faced a challenge as the dynamometers wound end up being larger than what was represented during the request for proposal process. That forced a redesign of the rooms where they would be housed.
More challenging still was equalizing the lengths of cables running between the dynamometers and their respective motor drives to ensure that data responses sent via electrical pulses would be synchronized. Short cables would need to have more slack to equal the longer cables. Yet the larger dynamometer rooms squeezed out any available space on the first floor. That triggered hasty revisions for a second- floor mezzanine. A smaller mezzanine had been planned to hold PEVEL’s environmental chamber machinery; but its size would need to be expanded to accommodate the dynamometer motor drives. The new mezzanine eventually encompassed the entire area above the sides and front of the chamber.
Each dynamometer moves atop three translation rails, which require alignment to within tenthousandths of an inch of each other and between the two dynamometer rooms. Any misalignment would jam the translation system drive and prevent the dynamometers from moving.
PEVEL also posed an electrical design challenge. The dynamometers in the lab are regenerative (in other words, their kinetic energy absorbed from the running vehicles produces electric power that can be used or stored). In this case, however, the power produced by the dynamometers could not be returned to the Detroit Arsenal’s electrical grid. Since the arsenal infrastructure could not meet GSPEL’s power demands, the lab needed a new electrical feed from a different substation. The different power grid meant GSPEL’s regenerative power could not be circulated for re-use by the arsenal.
Designers tried unsuccessfully to work out an arrangement to sell the power to a local electric utility. As it turned out, further calculations determined that the environmental chamber load would always exceed the dynamometers’ electric production capacity. The system would be mostly self-sufficient with no power wasted and no need to export power.
Vibration was another major concern. Engineers knew early on that figuring out how to absorb the powerful vibrations of the dynamometers would be daunting. A large mass was going to be necessary to isolate the vibrations—but the scale of construction was unknown.
When finally completed, the concrete seismic mass under PEVEL would end up being 80-ft-long by 60-ft-wide, and nearly 5-ft-thick. Building it was no simple matter. A train of 60 concrete trucks ran for six straight hours to pour the bottom 4-ft of the mass. The top 9-in required a separate pour to enable cast-in trenches to be formed accurately for the dynamometer translation rails. Concrete was pumped rather than poured to improve conveyance speed.
PEVEL’s dynamometers reside in rooms adjacent to each side of the environmental chamber. Each room is equipped with three translation rails upon which each dynamometer can move. The rails are 75-ft-long and require alignment to within ten-thousandths of an inch of each other (0.010-in) and between the two dynamometer rooms. The slightest misalignment would cause jamming of the translation system drive and clamping system and would prevent the dynamometers from moving.
Moreover, the exacting specifications imposed tighter deadlines, some added costs and the need for adaptations on the fly. The HVAC system in the dynamometer rooms had to be functional almost a year ahead of normal in order to control the temperature of concrete, rails and grout during the setting phase. Failure to control temperature would have meant uneven setting and a loss of alignment tolerance. And, the rail alignment required 80 custom-made jigs just to hold the rails in place until the grout set.
Power and Energy Vehicle and Environmental Lab (PEVEL) – The centerpiece lab of the GSPEL facility, it is the point for sub-system integration and complete vehicle system testing.
Power Lab – Enables testing and evaluation of major vehicle electrical systems.
Electrochemical (Battery) Lab – Equipped with three large explosion resistant battery test chambers, it enables safe testing of advanced chemistry battery packs as well as traditional lead-acid batteries.
Electric Components Lab – Enables evaluation of hybrid electric power trains and the development of hybrid motor technology.
Fuel Cell Lab – Provides capability for developing and evaluating fuel cell components and jet propulsion fuel reformation systems.
Thermal Management Lab – Designed for testing thermally managed mechanical and electrical components at the test bench scale.
Calorimeter Lab – Designed for testing heat exchanging equipment including radiators, charge air coolers and oil coolers.
Air Filtration Lab – Capable of testing the air flow characteristics of various- sized filter media at four different flow test benches. Utilizes varying air flows from 250-SCFM to 12,000- SCFM, while using dust feeders to simulate up to four times zero visibility for evaluation of every air filter and air cleaner in the military inventory.
During the initial testing of the PEVEL chamber, an issue arose with regard to the environmental chamber fans used to simulate wind speed. The chamber design had called for specific design pressures and flow rates at temperatures and the selected contractor submitted a fan curve meeting all of the requirements. However, once the fans were installed and operating, testing revealed they produced an insufficient flow rate. This resulted in the chamber manufacturer having to replace the three 5-ft-diameter centrifugal fans with three more expensive, but better performing, axial fans. This set the project back about three months due to the considerable re-work needed in the chamber.
The PEVEL chamber uses a heat transfer fluid to move thermal energy between the chamber, chiller and heater. The thin fluid, called Syltherm, is preferred because it can be easily pumped at low temperatures and possesses good thermal heat capacity. Those qualities also make it easier for Syltherm to leak. To detect any possible leaks, technicians added dye to the Syltherm. The chamber heat load capacity test revealed that the system was not meeting the expected capacity. A blockage in one of the chiller heat exchangers was suspected. An inspection found that the dye was collecting in the heat exchanger and functioning as an insulator.
The Syltherm supplier checked with chemical manufacturers and determined that 10 times the amount of dye needed was added. The solubility of the dye in Syltherm is reduced significantly at temperatures below -20°F, which explains why the dye had collected in the chiller.
Workers cleaned out the heat exchanger, but could not eliminate all of the dye from the system. They operated the chamber at cold temperatures, draining Syltherm near the coldest sections to collect the excess dye in the locations where it would fall out of the mixture. A side-stream filtration system was installed to help lower the bulk concentration of dye. These actions ultimately resolved the problem so that the chamber could meet the design requirements and pass its tests.
The turn-key nature of the project was unique for the USACE Detroit District, with the equipment going into the building being the main focus. While the testing and commissioning requirements for the equipment were extensive and very time consuming, in the end, that work resulted in a high-quality product.
GSPEL’s grand opening was celebrated as scheduled on April 11, 2012—less than three years after breaking ground. Attendees included military and government dignitaries, scientists, and leaders from industry and academia. Those involved in the project demonstrated over a threeyear period that such a wide-ranging and complex undertaking demands nothing less than consistent planning, communication and flexibility among key principals and stakeholders. They were up to the task. And the U.S. military, our servicemen and women, and the nation’s security will benefit as a result.