Description of Requirements_Traverse_14Jul2021.pdf

Description of Requirement Wind Tunnel Traversing System

Background:

The Engineer Research and Development Center (ERDC), Geotechnical and Structures Lab

(GSL), has a requirement for an automated traversing system to be installed in the new GSL wind tunnel.

The Synthetic Environment for Near-Surface Sensing and Experimentation (SENSE) is a new US

Army research facility nearing completion (Figure 1a). The facility consists of a large low-speed, climate-controlled wind tunnel that can be interfaced with large soil test-beds (Figure 1b). By packing the soil test-beds with any soil(s) and vegetation and subjecting them to various climate conditions, nearly any environment on Earth can be reproduced in the laboratory setting.

Figure 1: (a) Overview of the SENSE facility and (b) coupling of the wind tunnel test-section with a soil test-bed to create a synthetic environment.

This unique research facility allows above and belowground conditions to be carefully prescribed and maintained as necessary for any experiment; high spatiotemporal measurements of key atmospheric and subsurface state variables can be continuously monitored with state-of-the-art sensor technologies. The level of control offered in synthetic environments furthermore makes it ideal for generating data for improved process understanding and model validation, testing new materials and prototypes, and improving sensor signal interpretation.

Three-axis automated traversing systems are commonly installed in wind tunnels (Figure 2a) to provide remote access to the test-section (i.e., location where experiments occur) while experiments are running. Sensors and other payloads are mounted to these systems and moved from location to location with millimeter precision to make measurements or perform useful tasks.

This is ultimately done to prevent windows in the test-section from being opened mid experiment which subsequently disturbs the conditions within. These traverse systems are comprised of two long motorized precision carriage rails or linear actuators that extend the whole length of the test-section (see x, x’ in Figure 2b). Shorter precision linear actuators with smaller drive systems are used in the lateral (y) and vertical (z) directions as shown in Figure 2b. A centralized programmable logic controller (PLC) is used to control these systems. As wind tunnels in operation

b) a) around the world have different test-section designs, there is no such thing as a single turnkey traversing system that can be readily installed in place. Custom systems instead need to be designed and fabricated to meet the unique design and operation criteria which include: test-section dimensions, space limitations/constraints, aerodynamics, maneuverability (movement speed, precision/accuracy, repeatability of movements), total system weight, the environmental conditions in which it must operate, longevity, and the user interface for controlling its movement.

Figure 2: Example of (a) a wind tunnel traverse installed in the test-section and (b) system components.

Scope:

The purpose of this contract is to procure an automated three-axis traverse system for the SENSE wind tunnel test-section. The contractor shall provide all resources to design, fabricate, assemble, and install the wind tunnel traverse meeting the following specifications: Note all figures and tables referenced below can be found in the appendix at the end of this document.

- The traverse shall be a three-dimensional system. It must be able to move in each of the three coordinate systems (x-, y-, and z-) both simultaneously and individually.

- The traverse will be installed in a test-section with physical dimensions of 24 ft (731.52

cm) length (x-axis), 39 inches (99.06 cm) width (y-axis) and 39 in (99.06 cm) height (z-axis) – see Figure 3.

- The total x-axis travel distance shall be 26 ft (792.48 cm) in length. This ensures that when the traverse is not in use, it will sit 24 inches (60.96 cm) out of the test-section (Figure 4).

- If two individual x-axis linear actuators are employed, they must move simultaneously to prevent any binding.

- The y-axis travel distance shall be as large as possible within the confines of the test-section’s 39-inch (99.06 cm) width.

- In order to have adequate clearance in the test-section, no fixed part of the z-axis shall be closer than 14 inches (35.56 cm) to the floor of the test-section (Figure 5). This ensures that the traverse can clear large obstacles in the test-section.

- The z-axis must be able to accommodate different attachments for mounting extension arms, sensors, or other payloads.

- A minimum 3-inch (7.62 cm) clearance between the ceiling and the traverse (excluding mounting hardware) must be maintained at all times (Figure 6).

b) a) x x’ y z

- The traverse shall be mounted from the walls of the test-section. The mounts must be placed at a height of 37.5 inches (95.25 cm) to avoid existing windows in the test-section

(Figure 7). The mount can be bolted through the side walls as shown in Figure 8. The test-section is constructed of 1-inch (2.54 cm) nominal plywood supported at seven locations by steel Unistrut members (Figure 9). Each wall has a total of 13 pre-drilled and threaded holes that can accommodate 5/16-inch (0.794 cm) bolt sizes (Figure 9). A larger bolt size may be possible to accommodate given prior discussion and approval.

- The physical dimensions of the various traverse components shall be as small and aerodynamic as possible to minimize the impact of the traverse on airflow in the test-section. No part of the x-axis system components shall be lower than an elevation of 34.5 inches (87.63 cm) as shown in Figure 10. This is done to ensure that the when the y-traverse is not at a given location, there is a minimal amount of window space blocked by the traverse.

- The total weight of the traverse system (including e.g., linear actuators, motors, hardware) shall not exceed 550 pounds (249.476 kg).

- The mounts for the traverse shall not deflect more than 0.1 mm under the load of the rest of the traverse system.

- The traverse system shall be able to accommodate (i.e., transport) a maximum payload of

11 pounds (5 kg).

- At a minimum, the movement of the traversing system shall be repeatable and precise to within 0.19 inches (5 mm) streamwise (x-axis) and laterally (y-axis). The precision and repeatability of movement must be precise to 0.039 inches (1 mm) in the vertical (z-axis) direction.

- Fluid, smooth motion is required. A maximum movement speed of 0.5 mph (22 cm/s) shall be permissible for the x-axis and 0.1 mph (4.47 cm/s) for the y-axis and z-axis to ensure that sensitive payloads are not damaged. Note that the speed shall be adjustable – see programming requirements below.

- All traverse components located in the test-section must be able to operate in the adverse environment of the wind tunnel. See Table 1 for summary.

- The contractor shall provide a design that ensures system longevity. The linear actuators or equivalent and drive system shall have a minimum lifetime travel distance of 1,553 miles

(2,500 km) for the x-axis, 760 miles (1,224 km) for the y-axis, and 410,104 miles (660,000

km) for the z-axis.

- Cable management of all required controller and power cables shall be incorporated into the design (Figure 11). Cabling is not to be suspended or allowed to hang anywhere within the test-section. Research personnel will not have access to the test-section during movement to help coil or feed cable. A flexible cable carrier for example, was used in a previous traverse system.

- The cable management design shall be expandable in that it can accommodate the addition of sensor cables at a later date.

- Limit switches for all directions shall be included in the design as a safety precaution.

- All wiring shall exit only from a single location at the downstream exit of the test-section

(Figure 12).

- Standard 110V wall outlets are available outside and above the test-section to provide power to the motors and other electronics as shown in Figure 13.

- There are two possible locations where the PLC can be located – all cabling will have to be run from the motors and controllers to this location. These options are presented in Figure

14 and described above in order of preference:

o If the PLC is rated for the operating temperatures of the climate chamber (room housing the test-section) defined in Table 2, then it can be installed immediately outside the downstream exit of the test-section (Figure 14a and 14b). This space has dimensions of 7 x 14 x 36 inches (17.78 x 35.56 x 91.44 cm).

o All cabling can be fed through a nearby 4-inch (10.16 cm) diameter PVC pipe as shown in Figure 14a and 14c. Power is available outside the climate-chamber near this location; there are no space constraints like Option 1.

- All cabling necessary for controlling and powering individual components must be able to accommodate the length of the test-section and the distance to the PLC.

- The PLC shall be sufficiently large (i.e., number of available slots) so as to be expandable, allowing additional equipment (e.g., motors) and sensors (e.g., relative humidity-temperature) to be added.

- The PLC shall be fully programed by the contractor to meet the following specifications:

o All programing shall be done using the SI measurement system.

o All coordinate locations and inputs should be given in units of millimeters.

o The reference (0, 0, 0) location, or “home” position shall be defined as the south side of the downstream exit of the test-section as close to the ceiling as the z-traverse can travel (Figure 15).

o There shall be a capability to program several screens that the user can navigate/switch between. The following is a description of desired screens that would be included

(with the ability to provide more in the future):

▪ Screen 1: System status – This screen shall display the status of the individual components of the traverse system. This is where system alarms shall be displayed if there is an issue with one of the components. There shall be a button that is used to engage/disengage the entire system. When disengaged, all of the motors shall be locked and any inputs from the user shall be ignored and a warning provided.

▪ Screen 2: Speed Adjustment – This screen shall facilitate the adjustment of the motor speeds. There shall be hard limits applied so that the x-axis can only travel between 0.01 mph (0.5 cm/s) and 0.5 mph (22 cm/s) and the y-axis and z-axis between 0.002 mph (0.1 cm/s) and 0.1 mph (4.47 cm/s).

▪ Screen 3: Movement Controls – This is the screen that allows the user to move the traverse to any given location. The screen shall prominently display the current location of the traverse (defined in terms of its coordinate system). There shall be three different movement types available from this screen. Note that the first two will be the primary approaches used.

• Coordinate – the user can enter any x, y, z coordinate within the physical travel bounds. If an unrealistic value is assigned, an error shall be thrown.

• Jog – the user can manually adjust the position of the traverse using

“pushbuttons”. The current coordinate/position of the traverse in the software shall be updated and displayed automatically. This will be used for fine tuning the location of the traverse.

• Automated Run – the user can prescribe spatial coordinates as a function of time. This can be inputted as matrix and then launched using a “run” button.

▪ Screen 4: Automated Run – this is the screen that would be used to define the run matrix.

▪ Screen 5: Run/History Log – This is a screen where past run information

(time/date) and alarms can be stored.

▪ Screen 6-n: Future – additional screens to be added in the future to accommodate expansions to the PLC.

- An HMI with a minimum screen size of 9 inches (22.86 cm) shall be provided to interact with and control the traverse. A built-in keyboard feature is desirable.

- The HMI shall have a quick response and feedback for the machine jogging discussed above.

- The HMI shall be mobile. As per security requirements, the HMI must be tethered (i.e., not

Wi-Fi enabled). A minimum cable length of 40 feet (12 m) shall be provided to ensure that the HMI can be moved to various work areas where control will be needed (Figure 16). The

HMI shall be easy to disconnect from the PLC so that its cabling can be fed through the 4-inch (10.16 cm) diameter PVC pipes (Figure 16).

- The contractor shall provide a perpetual license (where applicable) for all software necessary for programing and running the PLC.

- The software shall support datalogging capabilities.

The contractor shall provide assistance for on-site installation and provide training.

Government Provided:

The Government will provide available test-section blueprints, CAD-drawings, and photographs of the location where the traverse will be installed upon request. The contractor furthermore is encouraged to arrange an onsite visit to facilitate an opportunity to take additional photos and confirm measurements. To request blueprints, CAD-drawings and photos and/or a site visit, contact Angie Stokes and angela.m.stokes@usace.army.mil

Anticipated Interim Milestones:

The contractor shall submit the DRAFT design to the ERDC-GSL within 30 calendar days of award for review and approval. NOTE: Minor adjustments of the specifications will be considered to accommodate a proposed design.

The contractor shall package and ship the complete system to the ERDC-GSL no later than 1

November 2021.

Delivery:

Complete on-site installation and training shall be complete no later than 15 November 2021 mailto:angela.m.stokes@usace.army.mil

Engineering Research and Development Center

3909 Halls Ferry Rd.

Geotechnical Engineering and Geosciences Branch (Bldg. 3396)

Vicksburg, MS 39180

Acceptance:

A series of tests involving the movement of the traverse to different locations will be conducted to ensure all performance criteria are met.

Figure 3a: Overview of the wind tunnel. The test-section is denoted by the red rectangle and the climate chamber the blue rectangle.

Figure3b: Elevation view showing the wind tunnel test-section where the traverse will be installed.

Figure 3c: Elevation view showing the interior of the test-section where the traverse will be installed.

Figure 4a: Elevation view showing the south side of wind tunnel test-section with an example of a traverse (demarcated in black) installed inside.

Note that the y/z-axis is located at a forward position in this schematic.

Figure 4b: Elevation view showing the north side of the wind tunnel test-section with an example of a traverse (demarcated in black) installed inside. Note that the y/z-axis is located at its “home” location in this schematic.

Figure 4c: Plan view showing an example traverse (demarcated in black) installed within the test-section. Note that the y/z-axis is located at a forward position in the schematic.

Figure 5: Schematic showing the maximum vertical extent of the z-axis of the traversing system.

Figure 6: Schematic showing the minimum spacing distance from the ceiling in which no part of the traverse (demarcated in black) outside the mounting hardware may be located.

Figure 7: Schematic showing the mounting height for the traversing system on the side walls of the test-section.

Figure 8: Schematic showing the locations of the pre-drilled and threaded 5/16-inch holes (stars) where the system can be supported from.

Figure 9a: Image depicting the wind tunnel test-section exterior. Pre-drilled and threaded side-wall connections (red circles) can be used to secure the traversing system to the side walls of the wind tunnel test-section.

Figure 9b: Image depicting the wind tunnel test-section interior. Pre-drilled and threaded side-wall connections (red circles) are for securing the traversing system to the side walls of the wind tunnel test-section.

Figure 10: Schematic showing the lowest allowable extent of the x-axis of the traverse.

Figure 11: Example of cable management for a traversing system in a wind tunnel test-section using flexible cable carriers.

Figure 12a: Schematic depicting the location where all cables may exit the wind tunnel test-section (red rectangle).

Figure 12b: Image showing the space at the down-stream exit of the test-section where cabling may be fed.

Figure 13: Schematic identifying the location of the available power supply (demarcated by red rectangle) for the traversing system.

Figure 14a: Locations where the PLC can be located within the experimental test-facility. Option 1 is located immediately above the roof of the wind tunnel test-section. Option 2 is located outside of the environmental chamber; all connections and cables will need to be fed through a 4-inch

(10.16 cm) diameter PVC pipe identified by the green rectangle.

Figure 14b: Space available for the Option 1 PLC location. Note the available power source. Example wires being fed from the test-section are denoted in red.

Figure 14c: Space available for the Option 2 PLC location. Example wires being fed from the test-section are denoted in red.

Figure 15: Conceptual image showing the “home” position corresponding to a coordinate of (0, 0, 0).

x

(0,0,0) y x z

Figure 16: Workspace depicting where the HMI will be used.

Table 1: Environmental Operating Conditions Within the Wind Tunnel Test-

Section

Variable Range

Wind Speed 0 to 22 mph (0 to 9.6 m/s)

Air Temperature 10 to 131 oF (-12.2 to 55 oC)

Relative Humidity 5 to 95 % condensing

Mist/Rainfall/Snow Variable rate, direct splash possible

Dust > PM10 (10 𝜇m)

Table 2: Environmental Operating Conditions Within the Environmental

Chamber

Variable Range

Air Temperature 10 to 95 oF (-12.2 to 37.8 oC)

Relative Humidity 5 to 75 %