SOW.pdf

Statement of Work

BACKGROUND

Particle Image velocimetry (PIV) technique is the state of the art non-intrusive, optical technique to provide instantaneous snapshots of velocity field within a three-dimensional volume in space. There are several levels of PIV. 2-D PIV, which uses one camera, measures 2-components of velocity in a plane. Stereo- PIV uses two cameras and measured 3-components of velocity in a plant. The highest level is the 3-D tomography PIV that uses 4 or more cameras and measures 3-components of velocity in a volume.

One of the fundamental issues with using tomographic PIV is the influence of “ghost particles”, which refers to potential, but unreal, solutions to that identifying smoke particles present in the flow. The presence of ghost-particles leads to incorrect values in measurements making them unusable. There are two ways to solve the problem: (1) ensure that the seeding is less than a threshold value (0.1 particles per pixel) or (2) add additional cameras to accurately resolve the location of the particle. Currently, Army has 4 cameras for conducting tomographic PIV.

The past experiments at the Army hover chamber confirmed that more cameras are necessary to reduce the “ghost-particle” issue. The present proposal is to purchase one more camera to complement the existing set of cameras to conduct tomographic PIV.

As mentioned earlier, Tomo-PIV measures velocities over a volume. The lasers that are used, however powerful, are often insufficient to produce enough intensity that increases S/N ratio when the volume is reasonably big (as in the case of many rotor experiments conducted at the Army hover facility). To compensate the loss of light, seed particles need to be bigger. Army currently has 3-smoke generators and the size of the particles are 0.25, 0.9, and 20 micrometers in diameter. Again, the past experiment proved that the aforementioned particles sizes were too small to increase the s/n ratio. The proposal includes a purchase request for one larger size (200 micrometer) seed generator that uses He and soap bubbles.

The following list of relevant equipment is held at the Army inventory.

1. LaVision Davis 10 operating license

2. LaVision PTU x synchronizer

3. Phantom VEO high speed cameras (4 units)

4. Seeders of different sizes (0.25, 0.9, and 20 micrometers)

Following is the list of items to be purchased:

1. Phantom VEO high speed camera 1 unit

2. Helium filled soap bubble generation seeding unit

Dr. Manikandan Ramasamy and Dr. David Shatzman are the end users of this system, and they work at the U S. Army Aeroflightdynamics directorate located at the NASA Ames Research Center in Moffett Field, CA. As the system must be used by a laser authorized user, both Drs. Ramasamy and Schatzman will be using the PIV system.

The PIV system will be used in many projects, beginning from validating numerical observations made by high fidelity computational codes in terms of identifying physical features in the rotor flow field, as well provide accurate measurements towards understanding the relationship between rotor wake and its performance.

OBJECTIVE

To acquire a seeding system that produces large enough particles towards increasing s/n ratio and a complimenting 5th camera (to the existing 4 cameras) that reduces the effect of ghost particles in the calculation.

PLACE OF PERFORMANCE

The following should list the location or department where the item/items or work will be done:

LaVision facility at Minneapolis, MN

PERIOD OF PERFORMANCE

When the work will begin and when the work will be completed.

August 30, 2023.