Richard R. Antcliff

Multispecies coherent anti‐Stokes Raman scattering instrument for turbulent combustion

A nonintrusive diagnostic system is described which permits simultaneous measurement of temperature, nitrogen number density, and oxygen number density in hostile combustion environments. This system is pumped by a 10‐Hz neodymium YAG laser, and signals are detected with an intensified photodiode array and dual photomultipliers. The system utilizes a folded BOXCARS beam arrangement, two probe dye lasers, dynamic range expansion, polarization rejection of nonresonant background, and multiplexing of the signal beams.

Coherent anti-Stokes Raman spectroscopy temperature measurements in a hydrogen-fueled supersonic combustor

Coherent anti-Stokes Raman spectroscopy (CARS) thermometry has been used to obtain static temperature cross sections in a three-dimensional supersonic combustor flowfield. Data were obtained in three span wise planes downstream of a single normal fuel injector which was located downstream of a rearward-facing step. The freestream flow was nominally Mach 2 and was combustion heated to a total temperature of 1440 K (yielding a static temperature of about 800 K in the freestream) to simulate the inflow to a combustor operating at a flight Mach number of about 5.4. Since a broadband probe laser was used an instantaneous temperature sample was obtained with each laser shot at a repetition rate of 10 Hz. Thus root-mean-square (rms) temperatures and temperature probability density functions (pdfs) were obtained in addition to mean temperatures.

Intensified silicon photodiode array detector linearity: application to coherent anti-Stokes Raman spectroscopy.

The linearity of an intensified silicon photodiode array multichannel detector is studied with coherent anti-Stokes Raman and other similar signals. Studies with diffuse and focused (spherically and cylindrically) signals resolved apparent saturation problems which limit the dynamic range of the detector. In addition, it has been shown that there is no short-range wavelength (473–532-nm) dependence on this saturation. Theoretical explanations for these phenomena are also included.

21st-Century R&D

OVERVIEW: In May 2007, Richard Antcliff challenged IRI members with a presentation asserting the notion that “three tsunamis” were about to break upon R&D managers, demanding urgent response. Technological exponentials, global demographic shifts, and the phenomenon of climate change all posed challenges that promised to transform R&D. How are R&D managers responding to the perfect storm created by those tsunamis? Survey results and interviews of managers at nearly 60 IRI-member companies revealed a range of responses. Open innovation, globally dispersed R&D operations, and an emphasis on collaboration suggest that the R&D lab of the future is far less likely to be “a lab” (especially a single, central corporate lab) than an intricate, dynamic innovation ecosystem. Not only R&D managers, but senior executives and government policy makers as well will have new roles to map in this model for twenty-first-century R&D.

CARS measurements of temperature and species number density in supersonic combusting flow

A supersonic combustion burner has been probed by coherent anti-Stokes Raman Spectroscopy and the results compared with computational fluid dynamics. Simultaneous measurement of temperature, nitrogen number density and oxygen number density have been acquired throughout the external combustion region. Preliminary calculations have been made on this system to estimate the burner performance. Comparisons of these techniques are included.

2012 R&D Trends Forecast

Since 1982, the Industrial Research Institute (IRI) has undertaken an annual survey of R&D spending expectations among R&Dand innovation-focused companies. Typically, the survey asks R&D leaders about their actual activity and budgets in the past year and their expectations and projections for the coming year. The publication of those results in the January issue of RTM has become an annual event. This year, IRI partnered with R&D Magazine, combining the Trends Survey with R&D Magazine’s Global R&D Funding Forecast (GFF) survey to extend the reach of the survey and expand its scope while preserving historic trends data relevant to IRI’s members. Three separate surveys were distributed in mid-2015, each receiving a different number of responses. On average, approximately 222 companies from 37 countries, mostly from North America and Europe responded to each survey. The bulk of respondents (60– 85 percent, depending on the survey) came from organizations spending less than

Laser diagnostics on a hypersonic combustor

50 million on R&D each year. The full 2016 GFF report can be found at http:// www.rdmag.com/articles/2015/11/2016-global-r-d-fundingforecast. Below, we’ve excerpted that full report to focus on elements of particular interest to RTM’s readership and appended IRI’s unique sea-change index analyses, not found elsewhere.

Laser remote sensing in atmospheric sciences, aviation safety, aeronautical research, and experiments from space platforms and high-flying aircraft

NASA-Langley has implemented a laser-based multipoint/multiparameter diagnostics system at its hypersonic direct-connect combustor, in order to measure both temperature and majority species densities in two dimensions, using spatially-scanned CARS; in addition, line-imaged measurements of radical densities are simultaneously generated by LIF at any of several planes downstream of the fuel injector. Initial experimental trials have demonstrated successful detection of one-dimensional images of OH density, as well as CARS N2-temperature measurements, in the turbulent reaction zone of the hypersonic combustor.

Opposed jet diffusion flames of nitrogen-diluted hydrogen vs air - Axial LDA and CARS surveys; fuel/air rates at extinction

Traditionally, the term laser remote sensing has been associated with active, optical measurements of the Earth’s atmosphere, lands, and oceans. In this paper, we concentrate our overview of laser remote sensing upon the Earth’s atmosphere in three disciplines: Atmospheric sciences, aviation safety, and aeronautical research. In atmospheric sciences, laser remote sensing has played a prominent role in the measurement of clouds, aerosols, the planetary boundary layer, chemical species, metals and ions, and in atmospheric dynamics in the temporal tracking of physical parameters and the direct measurement of atmospheric winds. Quite recently, laser remote sensing has been especially effective in correlative studies from ground and airborne platforms related to scientific studies in the eruption of Mount Pinatubo, and in following the dispersion of associated aerosols in the atmosphere, both in latitude and longitude. Laser remote sensing has also been very effective in studies related to the formation of the ozone hole, in the antarctic and arctic regions. Range-resolved measurements of atmospheric ozone have been made which track “in real time” the formation of the ozone hole and its subsequent dissipation. Laser measurements of the depolarization ratio of backscattering from particulates in the region of the ozone hole where Polar Stratospheric Clouds (PSC’s) form have provided unique information on the physics of the PSC’s and on the dynamics of the formation of the ozone hole phenomena. It is quite clear that laser remote sensing has proven to be an invaluable measurement technique for these types of chemistry investigations. The range-resolved measurement of atmospheric water vapor, correlated to the height of the planetary boundary layer and the distribution of aerosols over land and oceans, has also been demonstrated quite recently to be a unique measurement provided by laser remote sensing from aircraft. When this technique is developed from high flying aircraft and/or satellites, a major measurement technique will be available for the study of the hydrological cycle, globally. Soon, we should be seeing range-resolved measurements of atmospheric water vapor (50 meters) from a high-flying aircraft, with an accuracy better than 10 percent, as a routine measurement in atmospheric sciences. The historical evolution of laser remote sensing from the initial ground-based measurements of atmospheric aerosols in the early 1960’s to the sophisticated measurements from aircraft of today represent a unique evolution of technology in lasers and electrooptics, coupled to persistent attention to sound engineering development of a unique technique. For this paper, I have asked Dr. William B. Grant, a pioneer in laser remote sensing of the atmosphere, to provide this section entitled “Laser Remote Sensing in Atmospheric Sciences.“

Coherent Anti-Stokes Raman scattering with reflective optics.

An experimental study of H-air counterflow diffusion flames (CFDFs) is reported. Coaxial tubular opposed jet burners were used to form dish-shaped CFDFs centered by opposing laminar jets of H2/N2 and air in an argon bath at 1 atm. Jet velocities for extinction and flame restoration limits are shown versus input H2 concentration. LDA velocity data and CARS temperature and absolute N2, O2 density data give detailed flame structure on the air side of the stagnation point. The results show that air jet velocity is a more fundamental and appropriate measure of H2-air CFDF extinction than input H2 mass flux or fuel jet velocity. It is proposed that the observed constancy of air jet velocity for fuel mixtures containing 80 to 100 percent H2 measure a maximum, kinetically controlled rate at which the CFDF can consume oxygen in air. Fuel velocity mainly measures the input jet momentum required to center an H2/N2 versus air CFDF. 42 refs.