Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 124.94K | Year: 2016
This is a proposal to develop a unique, gated, picosecond, digital holography system for characterizing dense particle fields in high pressure combustion environments; a critical requirement clearly defined in the NASA solicitation. Most imaging methods fail to provide this capability because noise from multiple scattering buries the signal needed to acquire a useful image. Solutions to this problem are expensive, difficult to implement, and not ideal candidates for field experiments. The proposed innovation combines digital holography and picosecond, optical gating to limit the amount of optical noise sufficiently to enable high resolution, 3D imaging, effectively generalizing existing pseudo-ballistic imaging systems that have been used for imaging through dense particle fields. Storing the complete wavefront in a hologram enables use of a wide range of optical diagnostics methods including image processing and interferometry to improve image and information quality. The result is a new sensor concept that will be extremely useful in the experimental study of dense sprays and other particles fields, providing a detailed, instantaneous look at the structure and position of all of the particles as well as density field information in a large three dimensional sample volume. Moreover, the system can record dynamic information at high frequency.
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 149.98K | Year: 2015
ABSTRACT: An unseeded measurement technique is proposed for simultaneous spatially-resolved measurements of density, temperature, and velocity in hypersonic wind tunnel flows with the future potential for time-resolved measurement capability. A variant of filtered Rayleigh scattering (FRS) will be developed that takes advantage of unique monotonic relationships between molecular vapor cell filter transmissions and flow parameters of interest. The method relies on laser Rayleigh scattering from naturally present nitrogen or air molecules, and therefore requires no seeding of the flow. Thermodynamic properties of the test gas are obtained by measuring the transmission of Rayleigh scattered light through multiple vapor cell filters, which have sharp spectral cut-offs that can be tailored to provide good sensitivity to the properties of interest. A unique set of transmission coefficients, measured from images obtained with a camera, defines a given thermodynamic state, providing a non-intrusive instantaneous measurement. In the Phase I effort, we will demonstrate the technique with instantaneous measurements of density, temperature, and velocity along a line in a supersonic flow, laying the groundwork for later variants that will enable two-dimensional measurements of these quantities in various hypersonic flow fields, e.g., boundary layers, shock-wave/boundary layer interactions, and time-resolved measurements at high acquisition rates.; BENEFIT: The unique capability of filtered Rayleigh scattering (FRS) to measure flow fields, ranging from subsonic to hypersonic, with high spatial resolution is expected to be attractive to a wide range of customers, including U. S. and other governments test facilities, universities, and industrial testing sites. The FRS scheme described in this proposal can simultaneously measure multiple flow properties without the need for flow seeding, and hence represents an excellent diagnostic tool that can benefit vehicle designers and flow modelers. Some attributes of FRS having value to commercial aerospace interests include measurements supporting performance testing of advanced aircraft, rotorcraft, entry spacecraft such as Expendable Launch Vehicles (ELV) and Reusable Launch Vehicles (RLV), and propulsion concepts. Equal measurement capability is not readily available elsewhere in the world, thereby offering U.S. Government laboratories and the U.S. aerospace industry a unique capability for aerodynamic vehicle development. FRS is adaptable to applications in facilities of all sizes including those for full-scale model testing of aircraft and inlet flows, rotorcraft intra-blade and rotor-body wake interactions, vortex-control surface interactions, in-flight flows, propulsion system testing, and rocket test stand plumes. Another attractive feature of the FRS technique is the ability to measure temperature and density in turbulent flames and swirl combustors non-intrusively.
Agency: Department of Defense | Branch: Army | Program: SBIR | Phase: Phase II | Award Amount: 468.96K | Year: 2014
The goal of this Phase II program is to develop a simulation tool to estimate the aerodynamic effects of variable surface roughness, such as from the surface abrasion of helicopter rotor blades and the protective coatings that are applied to counteract it. The modeling is based on a displacement of origin methodology, within the k-omega turbulence model frameworks. Our initial investigations suggest that this method is effective in non-equilibrium boundary layers. Additionally we will implement and develop intermittency based transition models. We will work with OpenFoam and OVERFLOW CFD solvers which are widely used in the rotorcraft, and aerodynamics community. We expect to develop a state-of-the-art simulation tool for rotor blade drag estimation, and demonstrate capabilities through rotor simulations. The work plan consists of implementation and extension of the roughness models, in addition to development of a general capability for user defined measures of surface roughness. The effort includes verification and validation and also includes experiments to develop validation for configurations that are relevant to the rotorcraft application roughness strips and representative pressure gradients. A transition model will be implemented, with verification and validation using available transition data on turbine geometries.
Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase I | Award Amount: 79.35K | Year: 2015
This SBIR proposal describes an optical system that will provide a compact, easy-to-use tool for the measurement and characterization of deformable mirrors by contouring coated and uncoated surfaces being driven at high frequency. The proposed system is based on a state-of-the-art, real-time, two-wavelength, digital holography technique. This system combines an innovative optical architecture, compact laser diodes, an advanced CCD camera, and sophisticated data processing algorithms to generate high resolution 3-D profiles at kilohertz frequencies. During the Phase I project we will develop conceptual designs, perform trade study analyses, and perform experiments with measurement systems available at MetroLaser to demonstrate the feasibility of producing a prototype instrument during Phase II.
Agency: Department of Energy | Branch: | Program: STTR | Phase: Phase I | Award Amount: 149.95K | Year: 2014
The understanding of how fuel evaporates and mixes when injected into an engine cylinder is of key importance for the design of cleaner, more efficient vehicles. To meet the Department of Energy & apos;s goals of improving fuel efficiency in gasoline engines by 25 percent and diesel engines by 40 percent, advanced tools for research on fuel injection dynamics are needed. Existing techniques for investigating pre- combustion spray and vaporization dynamics in an engine cylinder do not allow both liquid and fuel vapor to be imaged simultaneously, yet this is a critical need. The proposed effort by MetroLaser and the Ohio State University (OSU) involves combining filtered Rayleigh scattering (FRS) with Mie scattering to allow imaging of both liquid and vaporized fuel simultaneously. A sheet of laser light will illuminate the region of interest in the spray, and two cameras will view the laser sheet, one employing FRS that blocks scattering from droplets to measure only fuel vapor, and the other measuring only Mie-scattered light from the droplets. A strong absorption line of iodine is employed as a narrowband notch filter on the FRS camera to block the Mie-scattered light. In this proposed effort, we will explore the feasibility of the FRS/Mie technique for application to engines and engine simulator facilities to advance the state of the art in fuel injector research. The Phase I will involve establishing the quantitative aspects of the technique with modeling studies using single component fuels, followed by canonical experiments to demonstrate the validity of the modeling. Experiments will also be conducted to demonstrate the technique on a gasoline spray from a fuel injector, which should reveal the strengths and weaknesses of the approach and will provide information needed for adapting the technique to an engine in future studies. Commercial Applications and Other Benefits: The proposed diagnostic technique should help bring about significant improvements in energy efficiency and emissions reduction in vehicles by providing engine designers with a tool to better quantify fuel injector performance. Boosting the efficiency of internal combustion engines is one of the most promising and cost-effective approaches to increasing vehicle fuel economy. The Department of Energy estimates that the United States can cut its transportation fuel use 20 to 40 percent through commercialization of advanced engines.1 The technology development effort proposed here would provide a critically important capability to help achieve these potentials.