BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Department of Aerospace Engineering - ECPv6.6.3//NONSGML v1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-ORIGINAL-URL:https://aero.iisc.ac.in
X-WR-CALDESC:Events for Department of Aerospace Engineering
REFRESH-INTERVAL;VALUE=DURATION:PT1H
X-Robots-Tag:noindex
X-PUBLISHED-TTL:PT1H
BEGIN:VTIMEZONE
TZID:Asia/Kolkata
BEGIN:STANDARD
TZOFFSETFROM:+0530
TZOFFSETTO:+0530
TZNAME:IST
DTSTART:20260101T000000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20260804T150000
DTEND;TZID=Asia/Kolkata:20260804T170000
DTSTAMP:20260807T163258
CREATED:20260803T045933Z
LAST-MODIFIED:20260804T105424Z
UID:10000143-1785855600-1785862800@aero.iisc.ac.in
SUMMARY:Multiphase Reactive Flows: From Dust Explosions to Metal-Fueled Detonations
DESCRIPTION:. \nExplosions in coal mines\, metal-processing facilities\, and other industrial settings occur with alarming regularity\, while reactive metal particles are being considered for energy-storage and propulsion applications. Despite a long history of research and its importance to safety and propulsion applications\, the physical mechanisms that govern the ignition\, combustion\, and detonation of reactive particles remain relatively unknown. Basic questions such as “How do particle size and thermal radiation affect dust-explosion propagation?”\, “What mechanisms govern the ignition and combustion of shock-dispersed metal powders?”\, and “How can reactive particles modify or sustain detonation waves?” remain unanswered. This presentation will discuss an ongoing numerical simulation effort aimed at answering these and other fundamental questions. This problem is addressed by solving a set of equations that couples a fully compressible reacting gas to a granular multiphase model that accounts for particle motion\, interphase drag and heat transfer\, and particle combustion. The results of these simulations indicate that shock propagation\, particle dispersal\, ignition\, combustion\, and thermal radiation are tightly coupled in a highly dynamic process. Results discussing the influence of particle diameter and thermal radiation on layered coal-dust explosions and the ignition and combustion of TNT-dispersed aluminum powder will be discussed. The presentation will close by discussing recent work exploring hybrid aluminum–hydrogen–air detonations\, including the role of particle size in extending detonation limits and modifying detonation structure. \n  \nSpeaker: Dr. Guhathakurta \nBiography:  \nDr. Guhathakurta received an M.Sc. degree in Physics from the Indian Institute of Technology Delhi\, and M.S. and Ph.D. degrees in Aerospace Engineering from the University of Florida. He subsequently held a postdoctoral appointment at Eindhoven University of Technology in the Netherlands. Dr. Guhathakurta is currently an Assistant Professor in the Department of Aerospace Engineering at Texas A&M University. His research focuses on a wide range of topics in multiphase reactive flows\, combustion\, and numerical simulation\, including dust explosions\, hybrid detonations\, thermal-radiation effects\, metal-particle combustion\, and high-speed propulsion.
URL:https://aero.iisc.ac.in/event/multiphase-reactive-flows-from-dust-explosions-to-metal-fueled-detonations/
LOCATION:Auditorium (AE 005)\, Department of Aerospace Engineering
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/png:https://aero.iisc.ac.in/wp-content/uploads/2026/08/Dr-RD-Seminar-Aug-6.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20260805T110000
DTEND;TZID=Asia/Kolkata:20260805T130000
DTSTAMP:20260807T163258
CREATED:20260728T061746Z
LAST-MODIFIED:20260802T102832Z
UID:10000141-1785927600-1785934800@aero.iisc.ac.in
SUMMARY:MTech(Res) : Design of an Ex-Situ Gas Sampling Layout with Various Probes and Their Performance Assessment for Accurate Emission Measurements
DESCRIPTION:Chemical kinetic mechanism development and validation require quantitative species data from canonical flames. Burner-stabilized pre -mixed flames provide a stationary post-flame region directly comparable to one-dimensional kinetic simulations. Ex-situ gas sampling delivers absolute CO and NO mole fractions from this region. The extraction step introduces two coupled biases. Reactions can continue inside the probe\, and the probe can perturb the flame upstream of the inlet. This thesis develops a coordinated ex-situ sampling framework for atmospheric McKenna burner-stabilized CH₄/air flames. The framework combines a sampling and dilution layout\, five sampling probes\, and a staged correction methodology. The measurements span fuel-lean to fuel-rich flames at three heights above the burner. The sampling and dilution layout is one of the principal contributions of the present work. The complete layout was designed and assembled in this work to adapt a portable gas analyzer (PG-350) for laboratory flame diagnostics. The PG-350 is built for stationary-source emissions monitoring rather than laboratory flame research. The design repurposes this industrial emissions instrument for high-precision species measurement in flames. The adapted instrument serves fundamental academic flame research. The layout delivers a conditioned\, metered\, and range-compatible sample to the analyzer. A vacuum pump extracts the sample using a sampling probe and drives it through the line. Two water-cooled drain separators\, designed and fabricated in this work\, remove the post-flame moisture. An Alicat mass flow meter measures the conditioned sample flow rate. A controlled N₂ dilution arrangement extends the CO measurement range beyond the analyzer’s full scale for the rich flames. Five sampling probes represent four reaction-quenching strategies. The aerodynamic-quench (AQ) probe was designed using a one-dimensional gas-dynamics model developed in this work. A brute-force screening selected its geometry against the pump and analyser constraints. The water-cooled (WC)\, pressure-quench (PQ)\, and uncooled probes were sized using non-reacting two-dimensional axisymmetric CFD. The uncooled-metal (UC-M) probe serves as a hot-wall reference. The uncooled-quartz (UC-Q) probe isolates the wall-material effect under the same geometry. Each probe was assessed experimentally and through two-dimensional probe-resolved reacting CFD in ANSYS Fluent. A residence-time method quantified the probe-induced upstream shift of the sampling location for the designed probes. A staged correction methodology recovers the sampled-gas composition from the conditioned analyzer reading. It corrects the mass flow meter reading for its gas-property mismatch. It then removes the imposed dilution and restores the moisture removed during conditioning. An independent route back-calculates the dilution ratio from paired CO₂ measurements. The methodology propagates the input uncertainties through the correction chain using the GUM framework. Reported values quote the expanded uncertainty on the corrected species. The corrected CO and NO were evaluated against a one-dimensional chemical kinetic simulation of the unperturbed flame. The comparison accounts for the probe-induced upstream shift of the sampling location. Each designed probe draws its sample from a location displaced toward the burner relative to its tip. The three designed probes were compared against the reference at their displaced sampling locations. The pressure-quench probe is the most consistent for both species. The water-cooled probe is a close alternative. The vacuum pump performance degraded due to moisture condensation in the pump head. Therefore\, it held the AQ suction above its design value throughout the campaign. The AQ probe is therefore off-design and cannot be ranked on equal terms. The uncooled-metal probe shows a large NO deficit in the rich flames from hot-wall surface reactions. The uncooled-quartz probe isolates the metal wall as the origin of this deficit. These rankings measure consistency with the kinetic reference rather than absolute accuracy. This work delivers outcomes of broader use to the combustion community. The framework offers documented guidelines to the community for ex-situ sampling experiments. It provides a comprehensive assessment of how each quenching strategy performs and which probe suits a given measurement. The corrected CO and NO data are suitable for chemical kinetic mechanism development and validation. Many detailed chemistry mechanisms exist\, yet reacting CFD of practical combustion devices requires reduced mechanisms that reproduce the target species profiles. The present setup allows reduced mechanisms to be validated quickly across flames spanning fuel-lean to fuel-rich conditions. A validated reduced mechanism can then support detailed CFD analysis of practical combustion systems. \n  \nSpeaker :  SARVAGYA SHARMA \nResearch Supervisor :  Irfan Ahmed Mulla
URL:https://aero.iisc.ac.in/event/mtechres-design-of-an-ex-situ-gas-sampling-layout-with-various-probes-and-their-performance-assessment-for-accurate-emission-measurements/
LOCATION:STC Conference Hall\, Ground Floor\, Department of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2026/08/SARVAGYA.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20260806T113000
DTEND;TZID=Asia/Kolkata:20260806T130000
DTSTAMP:20260807T163258
CREATED:20260717T092701Z
LAST-MODIFIED:20260802T105215Z
UID:10000137-1786015800-1786021200@aero.iisc.ac.in
SUMMARY:Ph .D.(Engg.): Explicit Filtering LES of turbulent swirling flows and multi-regime hydrogen flames
DESCRIPTION:The need to decarbonize power generation and aviation has established hydrogen as a promising fuel for next generation gas turbine combustion systems. However\, its high chemical reactivity significantly increases the propensity for autoignition and flashback under lean premixed conditions commonly used in hydrocarbon combustion systems. New combustor concepts based on direct fuel injection address these problems but typically produce lifted flames. These types of flames exhibit multi-regime combustion\, in which premixed and non-premixed combustion regions co-exist within highly turbulent swirling flow fields. Accurate numerical prediction of such reacting flows remains a major challenge as traditional models developed for hydrocarbon flames often fail to reliably predict the stabilization and combustion characteristics of multi-regime hydrogen flames. This thesis proposes a regime-sensitive combustion model using the thickened flame approach to extend the explicit filtering large eddy simulation (EFLES) method for computations of high Reynolds number (Re) reacting flows. A combustion regime index (CI) is defined based on the alignment between the gradients of mixture fraction and oxygen mass fraction to distinguish between premixed and non-premixed regions. The flame thickening treatment is applied selectively in premixed regions only. The model is implemented within an in-house high-order finite-difference flow solver that employs structured multi-block overlapping meshes to represent complicated geometries encountered in practical combustion systems. The predictive capability of the overall numerical methodology is systematically assessed through a series of increasingly complex flow configurations relevant to swirl-stabilized hydrogen combustors. The first case corresponds to an isothermal (Re ~ 27000) flow in the PRECCINSTA single nozzle swirl combustor. EFLES solutions show excellent agreement with the experimental data for flow field statistics and shape of the vortex breakdown bubble. Spectral proper orthogonal decomposition applied on time resolved velocity fields confirms that the EFLES method accurately reproduces the broadband turbulence structures and the coherent\, narrow band\, self-excited precessing vortex core oscillation. The combustion model performance is then evaluated using a canonical lifted slot jet flame configuration\, comprising a nitrogen diluted hydrogen slot jet of Re=8000 at 400 K issuing into a co-flow of heated air at 850 K. Entrainment of air into the jet core results in a stratified rich premixed flame alongside the primary non-premixed flame branch. The LES predicted flame lift-off height and flow field statistics are in good agreement with companion direct numerical simulation (DNS) results. Differences between LES and DNS solutions are small in premixed flame regions but increase with mesh spacing in non-premixed flame regions. The CI field is shown to clearly distinguish the two flame branches. This result is further validated a-posteriori using chemically explosive mode analysis (CEMA). Combined with EFLES\, the combustion model accurately predicts mixture fraction conditioned thermochemical statistics\, combustion mode distributions and the downstream evolution of premixed and diffusion flame branches in the lifted slot jet hydrogen flame. Finally\, a turbulent lifted hydrogen flame in the dual-swirl HYLON burner is investigated as a practical test case. The time-averaged mean flame shape and liftoff height is well captured in the LES solution. Good agreement is obtained between LES predictions and experimental measurements for statistics of velocity\, temperature\, and major-species mole fractions. CEMA reveals that a partially premixed flame branch is formed along the inner shear layer due to entrainment of hydrogen into the high-velocity annular air stream. The central diffusion flame branch is located within the vortex breakdown bubble between the fuel jet and the recirculating lean combustion products. The distribution of key thermochemical variables in mixture fraction space is also analyzed to characterize the two flame branches. Overall\, the results demonstrate that the proposed multi-regime thickened flame model\, coupled with explicit filtering LES provides a robust framework for high-fidelity LES of turbulent hydrogen flames. The methodology reproduces turbulent flow features\, flame stabilization and mixed combustion regimes across canonical and practical configurations. These results make the case for evaluating the performance of EFLES at higher operating pressures towards realizing a reliable computational engineering method for the design and analysis of future hydrogen gas turbine combustors. \nSpeaker :  ANINDYA DATTA \nResearch supervisor : Santosh Hemchandra
URL:https://aero.iisc.ac.in/event/ph-dengg-colloquium/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2026/08/ANINDYA.jpg
END:VEVENT
END:VCALENDAR