Prabhakar Venkateswaran, Ph.D.
Assistant Professor
- Milwaukee WI UNITED STATES
- Allen Bradley Hall of Science: S147
- Mechanical Engineering
Dr. Venkateswaran areas of expertise include thermodynamics, fluid mechanics, combustion, and gas turbines.
Education, Licensure and Certification
Ph.D.
Aerospace Engineering
Georgia Institute of Technology
2013
M.S.
Aerospace Engineering
Georgia Institute of Technology
2009
B.S.
Aerospace Engineering
University of Miami
2007
B.S.
University of Miami
Mechanical Engineering
2007
Biography
Areas of Expertise
Accomplishments
International Gas Turbine Institute (IGTI) Travel Award for Turbo Expo, American Society of Mechanical Engineers (ASME)
2013
Engineering Undergraduate Award, American Society for Nondestructive Testing (ASNT)
2005, 2006
Isaac Bashevis Singer Award, University of Miami
2003-2007
Foundation Sophomore Scholarship, American Institute of Aeronautics and Astronautics (AIAA)
2004
Affiliations
- American Society of Mechanical Engineers (ASME) : Member
- American Institute of Aeronautics and Astronautics (AIAA) : Member
- Combustion Institute : Member
Social
Event and Speaking Appearances
Simultaneous High-Speed Formaldehyde Fluorescence and Three-Dimensional Velocimetry in Lifted, Non-Premixed Jet Flames
35th International Symposium on Combustion San Francisco, USA, August 2014
Turbulent Flame Speed and Flame Brush Characteristics of H2/CO Flames
Indian Institute of Science Bangalore, India, June 2013
Turbulent Flame Speed Characteristics of H2/CO Flames and Challenges Associated with Performing High-Speed Laser Induced Incandescence
Fluid Dynamics Research Consortium Pennsylvania State University, State College, October 2014
Pressure and Fuel Effects on the Flame Brush Thickness of H2/CO Flames
Mechanical Engineering Graduate Students Organization Seminar Series Iowa State University, May 2013
Turbulent Flame Speed and Flame Brush Characteristics of H2/CO Flames
Indian Institute of Technology Chennai, India, June 2013
Selected Publications
Measurements of Stretch Statistics at Flame Leading Points for High Hydrogen Content Fuels
Journal of Engineering for Gas Turbines and PowerMarshall, A., Lundrigan, J., Venkateswaran, P., Seitzman, J., Lieuwen, T.
2017
Fuel composition has a strong influence on the turbulent flame speed, even at very high turbulence intensities. An important implication of this result is that the turbulent flame speed cannot be extrapolated from one fuel to the next using only the laminar flame speed and turbulence intensity as scaling variables. This paper presents curvature and tangential strain rate statistics of premixed turbulent flames for high hydrogen content (HHC) fuels. Global (unconditioned) stretch statistics are presented as well as measurements conditioned on the leading points of the flame front. These measurements are motivated by previous experimental and theoretical work that suggests the turbulent flame speed is controlled by the flame front characteristics at these points. The data were acquired with high-speed particle image velocimetry (PIV) in a low-swirl burner (LSB). We attained measurements for several H2:CO mixtures over a range of mean flow velocities and turbulence intensities. The results show that fuel composition has a systematic, yet weak effect on curvatures and tangential strain rates at the leading points. Instead, stretch statistics at the leading points are more strongly influenced by mean flow velocity and turbulence level. It has been argued that the increased turbulent flame speeds seen with increasing hydrogen content are the result of increasing flame stretch rates, and therefore, SL,max values, at the flame leading points. However, the differences observed with changing fuel compositions are not significant enough to support this hypothesis. Additional analysis is needed to understand the physical mechanisms through which the turbulent flame speed is altered by fuel composition effects.
Comparison of Three Interacting V-Flames to a Single Bluff-Body Flame at Two Reynolds Numbers
54th AIAA Aerospace Sciences MeetingCuller, W., Tyagi, A., Venkateswaran, P., OConnor, J.A.
2016
LAME interaction is an important phenomenon that occurs in a number of combustion technologies including gas turbines for both power generation and aircraft propulsion. Previous studies have shown that flame interaction causes changes in both the global and local flame behavior [1-3]. The time-averaged flame shape, flame static stability, and flame dynamic stability can vary with different levels of flame interaction. In this study, flame interaction is investigated using three interacting, planar, V-flames stabilized on triangular bluff bodies. Flameholders such as these are used in duct burners and afterburners. We have chosen this configuration to investigate fundamental flame and flow interaction processes as the configuration is largely two-dimensional, allowing for the use of planar diagnostics. The goal of this work is to compare the structure and turbulent characteristics of both the flow field and flame in a single bluff-body flame.
Effects of repetitive pulsing on multi-kHz planar laser-induced incandescence imaging in laminar and turbulent flames
Applied OpticsMichael, J.B., Venkateswaran, P., Shaddix, C.R., Meyer, T.R
2015
Planar laser-induced incandescence (LII) imaging is reported at repetition rates up to 100 kHz using a burst-mode laser system to enable studies of soot formation dynamics in highly turbulent flames. To quantify the accuracy and uncertainty of relative soot volume fraction measurements, the temporal evolution of the LII field in laminar and turbulent flames is examined at various laser operating conditions. Under high-speed repetitive probing, it is found that LII signals are sensitive to changes in soot physical characteristics when operating at high laser fluences within the soot vaporization regime. For these laser conditions, strong planar LII signals are observed at measurement rates up to 100 kHz but are primarily useful for qualitative tracking of soot structure dynamics. However, LII signals collected at lower fluences allow sequential planar measurements of the relative soot volume fraction with a sufficient signal-to-noise ratio at repetition rates of 10–50 kHz. Guidelines for identifying and avoiding the onset of repetitive probe effects in the LII signals are discussed, along with other potential sources of measurement error and uncertainty.
Scaling turbulent flame speeds of negative Markstein length fuel blends using leading points concepts
Combustion and FlameVenkateswaran, P., Marshall, A., Seitzman, J., Lieuwen, T.
2015
This work describes analyses of turbulent flame speeds, ST, of negative Markstein length fuel blends using leading point models. One implication of these models is that the maximum laminar burning velocity, SL,max, of highly stretched flames or “critically stretched flames”, is the appropriate flame speed scale with which to parameterize the turbulent flame speed. More specifically, it leads to a scaling approach for the turbulent flame speed of the form , where and τflow are the chemical time-scale associated with the leading point and a characteristic fluid mechanical time-scale, respectively. In this paper, we apply these scalings to data sets from the literature which explore pressure and fuel composition effects on ST. Amongst these data sets are new measurements, acquired by our group, of ST,GC for H2/CO mixtures at pressures up to 20 atm. It is shown that this approach can scale turbulent burning velocities from a range of different data sets, with significantly different fuel compositions, pressures, and stoichiometries. This result is particularly significant in understanding the strong pressure effects manifested in these data. Nonetheless, we also emphasize that time-scale, length scale, and Reynolds number effects on these correlations are difficult to differentiate as they exhibit similar pressure sensitivities, and further work is needed to conclusively understand the coupled (and very strong) effects of mixture stretch sensitivity and pressure on turbulent burning velocities.
Fuel effects on leading point curvature statistics of high hydrogen content fuels
Proceedings of the Combustion InstituteMarshall, A., Lundrigan, J., Venkateswaran, P., Seitzman, J., Lieuwen, T.
2015
Fuel composition has significant influences on the turbulent flame speed of mixtures with strong stretch sensitivity. These fuels effects are associated with reactant thermal-diffusive properties and stretch sensitivities, causing local variations in the burning rate along the flame front. This study is motivated by leading point descriptions of the turbulent flame speed, which argue that ST is controlled by the flame characteristics at its positively curved leading edge. It has been argued that the leading edge of the flame approaches “critically stretched” values in thermo-diffusively unstable flames, implying that the appropriate laminar flame speed to parameterize the turbulent flame speed is the maximum flame speed across all potential values of flame stretch, SL,max, as opposed to its unstretched value, SL,0. This paper describes an experimental investigation of the characteristics of the flame leading point in high stretch sensitivity flames to assess this hypothesis more fully. Measurements of the flame curvature were obtained with a low swirl burner (LSB) for several H2/CO mixtures at velocities from 30–50 m/s. These data show that the leading point conditioned curvature statistics are a strong function of the turbulence intensity of the flow. Counter to our expectations, however, the measurements show relatively weak influences of fuel composition on the leading point curvature of the turbulent flame front. As such, these results do not seem consistent with prior arguments that the increased turbulent flame speeds seen with increasing hydrogen content are the result of increasing flame curvature/stretch rates, and therefore SL,max values, at the flame leading points. Additional analysis is needed to understand the physical mechanisms through which the turbulent flame speed is altered by differential diffusion effects.
