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Gore, Jay P.

Publications and source records attributed to Gore, Jay P..

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Plasma Emission, Wave Speeds, and Temperatures of Laser-Supported Plasmas in Air

A study of the generation and subsequent expansion of plasmas using a single beam (532 nm) from the second harmonic generator of a Q-switched Nd:YAG laser is described. The plasmas in air are studied using an intensified charge-coupled device camera over periods of 1000 ns following the laser pulses. The plasma experimental results are interpreted in terms of wave speeds and plasma temperatures. Energy balance equations are considered to estimate the plasma temperatures and the laser-supported radiation (LSR) and the laser-supported detonation (LSD) wave speeds. Within 1000 ns observation time, the circular spectral images turn elliptical because of plasma expansion toward the laser beam. The plasma expansion increases with increasing laser irradiance. A laser irradiance range of [Formula: see text] yields LSR wave speeds between 45 and 170 km/s and LSD wave speeds of 90–130 km/s. The measured wave speeds are compared with the LSR and the LSR wave speed models. The plasma temperatures are between 90,000 and 120,000 K at 15 ns after the laser pulse based on measured emission spectra and are between 640,000 and 760,000 K at 3 ns based on the LSR model.

Engineering↗
DOE OSTI2022

Computation of conventional and alternative jet fuel sensitivity to lean blowout

Large Eddy Simulations (LES) are performed to compute the sensitivity of a conventional (A-2) and an alternate bio-jet (C-1) fuel to Lean Blowout (LBO). A realistic aviation gas turbine engine combustor configuration is considered. Reliable experimental LBO data and OH* chemiluminescence data for the conventional and alternate jet fuel in the combustor configuration have recently become available. The present work utilizes a highly automated, on-the-fly meshing strategy, along with adaptive mesh refinement, to demonstrate the feasibility of capturing the realistic combustion processes. A Lagrangian framework, with initial conditions specified using measurements of spray statistics, is used to model the fuel spray. Newly developed compact reaction mechanisms based on fuel surrogates are validated for the A-2 and the C-1 fuels. The compact reaction mechanisms are implemented using a detailed finite rate chemistry solver. Spray statistics computed by the present LES simulations compare well with available measurements at stable flame conditions near the lean blowout limit. The computed shape of the stable flame as represented by line integrated OH concentrations compares well with the experimental OH* chemiluminescence data. Lean blowout is reached by gradually decreasing the fuel flow rate in the computations, similar to that in the experiments. The results of the LES simulations effectively capture the fuel composition effects and estimate the sensitivity of the LBO limits to the fuel type. The computed trends in LBO limits agree within engineering accuracy with the experimental results for conventional and alternative aviation fuels. The methodology for predicting the fuel composition effects on the lean blowout limits in a fully resolved realistic, complex combustor is established for the first time.

Adaptive mesh refinement↗
DOE OSTI2020

A data-driven model for thermodynamic properties of a steam generator under cycling operation

The varying electricity demand from coal power plants due to the intermittent nature of renewable sources leads to load-follow and on/off operations referred to as cycling. Cycling causes transients of properties such as pressure and temperature within various components of the steam generation system.These transients cause increased damage because of fatigue and creep-fatigue interactions shortening the life of components. An algorithm is developed to identify cycling operations from the gross power data. The data-driven model based on artificial neural networks (ANN) is developed using 10 years data from Coal Creek Station power plant located in North Dakota, USA to estimate properties of the steam generator components during cycling operations. Furthermore, the uniqueness of this model is the ability to predict component properties for the cycling as well as base-load operations and is reported for the first time. The ANN model estimates the component properties, for a given gross power profile and initial conditions, as they vary during cycling operations. As a representative example, the ANN estimates are presented for the superheater outlet pressure, reheater inlet temperature, and flue gas temperature at the air heater inlet. The changes in these variables as a function of the gross power over the time duration are compared with measurements to assess the predictive capability of the model. Mean square errors of 4.49E-04 for superheater outlet pressure, 1.62E-03 for reheater inlet temperature, and 4.14E-04 for flue gas temperature at the air heater inlet were observed.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2019

Large eddy simulation of hydrogen piloted CH 4 /air premixed combustion with CO 2 dilution

Large eddy simulation (LES) of constant adiabatic temperature, hydrogen-piloted, turbulent lean premixed methane/air jet flames with varying amounts of CO 2 addition are reported. Constant adiabatic temperature is achieved by increasing the fuel flow rate slightly to account for the higher specific heat of CO 2 compared to N 2 . Such flames are relevant to low NOx gas turbines with high hydrogen content fuels and Exhaust Gas Recirculation (EGR). A newly designed burner called Piloted Axisymmetric Reactor Assisted Turbulent (PARAT) flame burner was utilized. The operating conditions in the experiment were selected to highlight the kinetic effects of CO 2 addition by matching the Reynolds numbers, Lewis numbers and adiabatic flame temperatures. The LES simulations utilize a finite rate chemistry solver with DRM19 combustion mechanism with adaptive zoning and a dynamic structure turbulence model. A five-level adaptive mesh refinement (AMR) improves the velocity and temperature gradient resolution. The LES predicts the experimentally observed increase in flame length with CO 2 levels caused by a decrease in the turbulent flame speed. The computational results also capture the experimentally observed departure from the thin flame limit and a collapse of the root mean square (RMS) versus mean temperature profiles for the three levels of CO 2 . The flame structure analysis illustrated super-equilibrium CO concentrations because of non-equilibrium chemistry effects caused by the external addition of CO 2 .

08 HYDROGEN↗
DOE OSTI2019

Effects of turbulent flow regime on perforated plate stabilized piloted lean premixed flames

An experimental study of the effects of turbulent flow regime on the flame structure is conducted by using perforated-plate-stabilized, hydrogen-piloted, lean premixed methane/air turbulent flames. The underlying turbulent flow field was investigated using two-dimensional three-component particle imaging velocimetry (2D3C-PIV) with two perforated plates of different blockage ratios. The flow data allowed a separation of the turbulent flow regime into axial velocity stream dominated and vortex dominated flows. A plate with 62% blockage ratio was used to establish the stream-dominated flow regime and another with 86% blockage ratio was used to establish the vortex-dominated flow regime. OH laser-induced fluorescence was used to study the effects of the turbulent flow regime on the mean progress variable, flame brush thickness, flame surface density, and global consumption speed. In comparison with the stream-dominated flow, the vortex-dominated flow makes a wider and shorter flame. Also, the vortex-dominated flow has a thicker horizontal flame brush and a thinner longitudinal flame brush. Especially, the spatial variation of the horizontal flame brush thickness for the vortex-dominated flow does not follow the turbulent diffusion theory. The vortex-dominated flow shows a relatively constant flame surface density and the stream-dominated flow shows a decreasing flame surface density along the streamwise direction. The flame surface density for the vortex-dominated flow is higher than the one for the stream-dominated flow. Lastly, the vortex-dominated turbulent flow shows a much higher consumption speed in comparison with that of the stream-dominated turbulent flow with identical velocity fluctuation levels.

42 ENGINEERING↗
DOE OSTI2011

Purdue Hydrogen Systems Laboratory

This project spanned two distinct areas of importance to the hydrogen (H 2 ) energy program. The first involved hydrogen storage and the second involved hydrogen production.

08 HYDROGEN↗