Research

Facilities - Optical

The majority of our research is focused around the visualization of fluid flows. For these visualizations we apply a range of optical systems and techniques which range in field of view from micrometers to several meters. All of our optical systems are compatible with our high speed digital cameras to provide visualizations at rates up to 1 MHz.

Full-Scale Schlieren System

An image from the full-scale schlieren
system visualizing a gas leak from a
piping system and a worker attempting
to locate the leak with a conventional
hand wand.

We have developed a lens-and-grid-type schlieren optical flow visualization system using a very large grid as a light source, and having a field-of-view of 2.1x2.7 m (7x9 feet), making it by far the largest schlieren system in the world. The design of the system literally makes the building shown below into a giant camera. This system uses retroreflective highway-sign-type material for the source grid which covers an entire wall. The optics are located on the wall opposite the source grid and test area is located in the middle of the building. The intended purpose of this instrument is to visualize and study a variety of full-scale airflows such as those associated with shock waves, HVAC equipment, automobiles, home appliances, fires, clean rooms, welding and spraying operations, abrasive blasting, air curtains, and airflow interactions with the human body. It is especially useful for demonstrating full-scale heat transfer phenomena. Click here to read a detailed paper about our system.

A schematic of the full-scale schlieren system with a person standing in the test
section, which is approximately 2 x 3 m.

1-meter Schlieren System

The human thermal plume is visualized
with the 1m schlieren system.

The Lab's 1-meter-diameter schlieren optical flow visualization facility is one of the largest mirror-type systems in the world. It can detect thermal gradients in the atmosphere of less than 1 degree C/cm, and has been used in clean room airflow research, studies of the thermal plume created by the human body, canine olfaction research, thermal spray research, and a wide variety of other studies.

A schematic of the full-scale schlieren system with a person standing in the test
section, which is approximately 2 x 3 m.

Retro-Reflective Shadowgraph System

A shadowgram of a student standing at a gas
grill during operation. The turbulent convection
plume of the heat and exhaust products from
the gas grill is clearly visible.

We have developed a modern retro-reflective shadowgraph system for the visualization of refractive flows, especially shock wave and heat convection applications. This shadowgraph system uses a 2.5 x 2.5 m retro-reflective screen, white-light arc lamp source, and is compatible with all of our digital cameras. This simple and portable system has been used in a wide variety of experiments both inside and outside of the laboratory.

Other Optical Facilities

0.76m z-type schlieren system
Focusing schlieren optical system
Portable and table-top schlieren systems of varying field of view (1-8 inch diameter)
Optical microscope

Additional Schlieren Images

Cleanroom

Human

Canine

Thermal Spray