One of the primary facilities used to collect data for validation purposes is capable of produding turbulent jets in a high velocity crossflow. Experiments can be run isothermally or consider mixing of these and other flow configurations at different temperatures. The cross flow is generated using a closed loop wind tunnel (denoted by blue lines below), while a seperate flow motivation skid with three lines controlled for flow rate and temperature is used to generate the jet flow (denoted by brown and red lines below).
A standard approach to the closed loop wind tunnel (shown below) is made using a large fan to motivate the flow and a contraction nozzle just before the test section which enables a uniform inlet profile for the crossflow. The jets enter the test section from above, leaving three sides of the test section available for diagnostic measurements. The target operating conditions include a jet Reynolds number of 50,000 and a crossflow velocity as high as 70 m/s. The three jet lines can be split into as many as nine inlets using manifolds for each line. The test section is 21.76 cm (height) x 45.72 cm (width) x 60.96 cm (length). Solid obstructions (e.g., array of cylinders) can be inserted into the test section to acheive conditions pertinent to specific applications. See our High Temperature Gas Cooled Reactor reserach for example.
Particle Image Velocimetry (PIV) can be performed when optical access is available and the flow is properly seeding with particles. A laser illuminated the particles and a camera can then track the movement of particle from one frame to the next, enabling calculation of velocities in the entire field of view. Our Tomographic PIV system uses volumetric laser illumination of the flow and four high speed cameras to capture 3-D velocity data along with the velocity gradients in all directions. With repetition rates as high as 10 kHz, valuable flow evolution characteristics can also be captured. This diagnostic equipment is also used to capture planar velocity data, where uncertainties can be quantified with a high degree of confidence.
The pool boiling facility (shown below) is designed to have the following three key features: quickly interchangeable surfaces, conduction-based heat flux measurement and automated boiling curve generation. The facility uses a 304 stainless steel heater core with four inlaid cartridge heaters to supply a measured and controlled heat input to the thin boiling surface (test piece) located at the bottom of the pool. Auxiliary heaters and reflux condensers ensure constant temperature and fluid level during experiments. To ensure minimal loss of mass, two allihn reflux condensers are mounted on the top of the apparatus. Expanding steam condenses and returns to the pool. A central inner chamber is used to ensure momentum and thermal isolation. Four glass walls seal the inner chamber from the outer jacket to eliminate convective currents from the auxiliary heater. Heat transfer out of the inner chamber is significantly diminished due to the surrounding saturated water jacket. The reflux condensers are positioned above the inner chamber. Water always spills over from the inner chamber to the outer chamber to ensure a consistent water level in the inner chamber. If ever purity in the jacket were to become a concern, only condensed steam refills the inner chamber.
Additional equipment in the lab is used for diagnotic purposes. Multiple high accuracy calibration sources exist for velocity and temperature. Aside from these and other standard laboratory items (e.g., thermocouple welder, power supplies, data acquisition units), specialized capabilities also include the following:
Four high end desktops are used for small and medium sized computational jobs. Between these four, there are over 60 cores and 500GB of memory.
Ample High Performance Computing (HPC) resoures exist at Texas A&M University to meet the computational expense of high fidelity RANS and LES jobs. With successful grants through the XSEDE system, additional HPC resources are available.