Research

DMLS Enabled Turbine Nozzle Guide Vane

This study includes the design, validation, and fabrication via Direct Metal Laser Sintering (DMLS) of a gas turbine nozzle guide vanes (NGV) that incorporates three innovative cooling schemes specifically enabled by additive manufacturing. The novel NGV design is the culmination of an extensive research and development effort over a period of four years that included low and high speed cascade testing coupled with unsteady CFD for numerous candidate innovative cooling architectures. The final vane design (SJ-vane) consists of sweeping jet (SJ) film cooling holes on the suction surface, sweeping jet impingement holes at the leading edge and double-wall partial length triangular pin-fin with impinging jet at the trailing edge. Experiments with the two DMLS enabled vanes were performed at the Ohio State University Turbine Reacting Flow Rig (TuRFR) at engine relevant temperature (1375K) and Mach number conditions. Results showed improved cooling performance for the advanced cooling schemes (sweeping jet film cooling, impingement cooling and triangular pin-fin cooling) compared to the baseline cooling schemes.

Hossain, M.A., Ameri, A., Gregory, J., Bons, J.P., "Experimental investigation of innovative cooling schemes on an additively manufactured engine scale turbine nozzle guide vane," ASME. J. Turbomach. 2021;143(5):051004 -11. doi:10.1115/1.4049618 [pdf]

Sweeping Jet Film Cooling on a Transonic Turbine Cascade

The sweeping jet (SJ) film cooling hole has shown promising cooling performance compared to the standard shaped hole in low-speed conditions. The present work demonstrates the first attempt of sweeping jet film cooling at an engine relevant Mach number. An experimental investigation was conducted to study the sweeping jet film cooling on a nozzle guide vane suction surface. A well-established additive manufacturing technique commonly known as Stereolithography (SLA) was utilized to design a transonic, engine representative vane geometry in which a row of SJ holes was used on the vane suction surface. Experiments were performed in a linear transonic cascade at an exit Mach number of 0.8 and blowing ratios of BR = 0.25-2.23. The measurement of heat transfer was conducted with the transient IR method and the convective heat transfer coefficient (HTC) and adiabatic film cooling effectiveness were estimated using a dual linear regression technique (DLRT). Aerodynamic loss measurements were also performed with a total pressure Kiel probe at 0.25Cax downstream of the exit plane of the vane cascade. Experiments were also conducted for a baseline shaped hole (777-hole) for a direct comparison. Results showed that the SJ hole has a wider coolant spreading in the lateral direction near the hole exit due to its sweeping action that improves the overall cooling performance particularly at high blowing ratios (BR>1). Aerodynamic loss measurement suggested that the SJ hole has a comparable total pressure loss to the 777-shaped hole.

Hossain, M.A., Asar, M.E., Gregory, J., Bons, J.P., "Experimental Investigation of Sweeping jet film cooling in a transonic turbine cascade," ASME Turbo Expo 2019, Pheonix, AZ, Paper number: 2019-91678 [pdf]
Hossain, M.A., Asar, M.E., Gregory, J., Bons, J.P., "Experimental Investigation of Sweeping jet film cooling in a transonic turbine cascade," ASME. J. Turbomach. 2019;142(4):041009-11 [pdf]

Design of a nozzle guide vane (NGV) consisting advanced cooling concepts enabled by additive manufacturing

Transient thermal response of the sweeping jet film cooling hole at transonic flow condition. (Mach number = 0.8 )

Thermal field at a Blowing Ratio (M = 1)

Thermal field at a Blowing Ratio (M = 3)

Large Eddy Simulation (LES) of Sweeping Jet Film Cooling at High Blowing Ratio

Experimental and numerical investigations were conducted to study the effects of high blowing ratios and high freestream turbulence on sweeping jet film cooling. Experiments were conducted on a nozzle guide vane suction surface in a low-speed linear cascade. Experiments were performed at blowing ratios of 0.5-3.5 and freestream turbulence of 0.6% and 14.3%. Infrared thermography was used to estimate the adiabatic cooling effectiveness. Thermal field and boundary layer measurement were conducted at a cross-plane (x/D = 12) downstream of the hole exit. Results were compared with a baseline 777-shaped hole and showed that sweeping jet hole has a better cooling performance at high blowing ratios. The Thermal field data revealed that the coolant separates from the surface at high blowing ratios for the 777-shaped hole while the coolant remains attached for the sweeping jet hole. Boundary layer measurement further confirmed that due to the sweeping action of the jet, the jet momentum of the sweeping jet hole is much lower than that of a 777-shaped hole. Thus the coolant remains closer to the wall even at high blowing ratios. Large Eddy Simulations (LES) was performed for both sweeping jet and the 777-shaped hole to evaluate the interaction between the coolant and the freestream at the near hole regions. Results showed that 777-shaped hole has a strong jetting action at high blowing ratio that originates inside the hole breakout edges thus causing the jet to blow off from the surface. In contrast, the sweeping jet hole does not show this behavior due to its internal geometry and the sweeping action of the jet.

Hossain, M.A., Ameri, A., Gregory, J., Bons, J.P., "Sweeping jet film cooling at high blowing ratio on a turbine vane," ASME Turbo Expo 2019, Pheonix, AZ; Paper number: GT2019-91696 [pdf]
Hossain, M.A., Ameri, A., Gregory, J., Bons, J.P., "Sweeping jet film cooling at high blowing ratio on a turbine vane," ASME. J. Turbomach. 2020;142(12):121010 -11. doi:10.1115/1.4047396

Sweeping Jet Film Cooling on a Turbine Vane

The cooling performance of sweeping jet film cooling was studied on a turbine vane suction surface in a low-speed linear cascade wind tunnel. The sweeping jet holes consist of fluidic oscillators with an aspect ratio (AR) of unity and a hole spacing of P/D = 6. Infrared (IR) thermography was used to estimate the adiabatic film effectiveness at several blowing ratios and two different freestream turbulence levels (Tu = 0.3% and 6.1%). Convective heat transfer coefficient was measured by a transient IR technique, and the net heat flux benefit was calculated. The total pressure loss due to sweeping jet film cooling was characterized by traversing a total pressure probe at the exit plane of the cascade. Tests were performed with a baseline shaped hole (777- shaped hole) for comparison. The sweeping jet hole showed higher adiabatic film effectiveness than the 777-shaped hole in the near hole region. Although the unsteady sweeping action of the jet augments heat transfer, the net positive cooling benefit is higher for sweeping jet holes compared to 777 hole at particular flow conditions. The total pressure loss measurement showed a 12% increase in total pressure loss at a blowing ratio of M = 1.5 for the sweeping jet hole while 777-shaped hole showed a 8% total pressure loss increase at the corresponding blowing ratio.

Hossain, M.A., Agricola, L.M., Ameri, A., Gregory, J., Bons, J.P., "Sweeping jet film cooling on a turbine vane," ASME Turbo Expo 2018, GT2018-77099 [pdf]
Hossain, M.A., Agricola, L.M., Ameri, A., Gregory, J., Bons, J.P., "Sweeping jet film cooling on a turbine vane," ASME. J. Turbomach. 2019;141(3):031007-031007-11. doi:10.1115/1.4042070 [pfd]

Innovative double-wall pin-fin-jet for internal Cooling

Impingement cooling and pin-fin cooling are the two most widely used internal cooling techniques in modern gas turbine engines. The impinging jets are the most effective due to its high rate of heat transfer at the impinging region. But the induced cross-flow negatively affects the impingement heat transfer. In contrast, pin-fins are used in the blade cooling channels to enhance turbulent mixing and augment the local heat transfer. However, the added pin-fins introduce additional pressure loss that ultimately affects the overall thermal performance of the system. To mitigate these challenges, we propose a double-wall cooling concept, including impinging jet and partial length pin-fins for the advanced gas turbine cooling. The impinging jet will be used for internal cooling, and the added pin-fins will reduce the induced cross-flow and augment the local heat transfer internally. Besides, the partial length pin-fin will recover some of the pressure loss. The development of additive manufacturing will open the design space in such a way that we would be able to integrate such a compact design for the next generation gas turbine engine.

Hossain, M.A., Asar, M.E., Ameri, A., Bons, J.P., Conjugate Heat Transfer Study of Innovative Pin-Fin Cooling Configurations.," AIAA Scitech 2020 Forum, AIAA2020-0634 [pdf]

Leading-Edge Impingement Cooling (Sweeping jet)

A low-speed linear cascade was used to investigate sweeping jet impingement cooling in a nozzle guide vane leading edge at an engine-relevant Biot number. Sweeping and steady jets were studied at varying mass flow rates and freestream turbulence intensities. Infrared thermography and a thermal inertia technique were used to determine the overall cooling effectiveness and internal heat transfer coefficients of the impingement cooling configurations. The circular jet array provided higher overall effectiveness values at both freestream turbulence intensities. The sweeping jet array provided a broader heat transfer profile due to the spreading of the jet. Pressure drop was measured for each jet geometry, and the circular jet was found to have less pressure drop than the sweeping jet at a given mass flow rate.

Agricola, L.M., Hossain, M.A., Agricola, L.M., Ameri, A., Gregory, J., Bons, J.P., Turbine Vane Leading Edge Impingement Cooling with a Sweeping Jet.," ASME Turbo Expo 2018, GT2018-77073 [pdf]

https://sites.google.com/site/arifosu/research/LE_module_schematic.PNG

Sweeping Jet Film Cooling

A companion experimental and numerical study was conducted of the performance of a row of 5 sweeping jet (SJ) film cooling holes consisting of conventional curved fluidic oscillators with an aspect ratio (AR) of unity and a hole spacing of P/D = 8.5. Adiabatic film effectiveness ( ), thermal field ( ), convective heat transfer coefficient (h) and discharge coefficient (CD) were measured at two different freestream turbulence levels (Tu = 0.4% and 10.1%) and four blowing ratios (M = 0.98, 1.97, 2.94 and 3.96) at a density ratio (DR) of 1.04 and hole Reynolds number of ReD = 2800. Adiabatic film effectiveness and thermal field data were also acquired for a baseline 777-shaped hole. The sweeping jet film cooling hole showed significant improvement in cooling effectiveness in the lateral direction due to the sweeping action of the fluidic oscillator. An unsteady RANS simulation was performed to evaluate the flow field at the exit of the hole. Time resolved flow fields revealed two alternating streamwise vortices at all blowing ratios. The sense of rotation of these alternating vortices is opposite to the traditional counter rotating vortex pair (CRVP) found in a ‘jet in crossflow’and serves to spread the film coolant laterally.

Hossain, M.A., Prenter, R., Lundgreen, L.M., Ameri, A., Gregory, J., Bons, J.P., " Experimental and numerical investigation of sweeping jet film cooling," GT2017-64479
Hossain, M.A., Prenter, R., Lundgreen, R., Ameri, A., Gregory, J., Bons, J.P., 2017, " Experimental and numerical investigation of sweeping jet film cooling," Journal of Turbomachinery, 140(3), p. 031009 [pdf]

Effect of Rotation on Sweeping Jet

Numerical investigations were performed to evaluate the effects of rotation on a fluidic actuator flowfield. Both internal and external flow fields were investigated. A conventional wall attachment type fluidic oscillator with a throat aspect ratio of unity was considered. The rotation was applied at two axes of rotation. The first configuration (on-axis) considers the axis of rotation identical to the axis of the oscillator. The axis of rotation for the second configuration (off-axis) is offset (100D) from the axis of the oscillator. Three rotational speeds ( 5000, 10000 and 15000rpm) were considered. The corresponding rotation numbers (Ro) are 0.013, 0.026 and 0.039. Unsteady RANS calculations were performed to evaluate both time-accurate and time-averaged internal and external flow fields. Numerical results were validated by comparing the external flowfield of a stationary case with the experimental data and showed good agreement. The oscillation frequency drops with rotational speed due to a drop in averaged velocity inside the feedback channel. The time-accurate streamwise velocity and streamlines are presented that show the effect of rotation for both cases. The internal flow fields change slightly with rotation. However, a significant change in the external flow field was observed. For on-axis rotation, an out-of-plane motion induced by the Coriolis force was observed. For off-axis rotation, the local pressure gradient in the radial direction causes an asymmetric jet trajectory in the streamwise and spanwise direction.

Hossain, M.A., Ameri, A., Gregory, J., Bons, J.P., "Effects of Rotation on a Fluidic Actuator", AIAA Scitech 2019 Forum, AIAA SciTech Forum, AIAA 2019-0885. [pdf]

https://sites.google.com/site/arifosu/research/iso_view_2.png

Sweeping Jet Impingement cooling on Turbine Leading edge (Matched Bi-approach)

Experiments were conducted in a low-speed wind tunnel to investigate sweeping jet impingement cooling in a faired cylinder leading edge model at an engine-relevant Biot number (Bi). Both sweeping and steady jets were studied at varying mass flow rates, jet-to-wall spacing (H/D), jet pitch (P/D), and freestream turbulence. The effect of varying aspect ratio (AR) of the sweeping jet geometries was also studied. Infrared thermography (IR) was used to determine the overall cooling effectiveness. The overall cooling effectiveness decreases as H/D increases for the steady jet. However, the sweeping jet shows non-monotonic performance compared to the steady jet. At H/D = 5, the sweeping action is dominant and the overall cooling effectiveness improves significantly at this jet-to-wall spacing compared to the steady jet case. A high overall cooling effectiveness is observed for sweeping jets with an aspect ratio (AR) of unity. Due to a weak oscillation, the lower aspect ratio (AR = 0.5) fluidic oscillator tends to have a poor cooling performance compared to the high aspect ratio (AR = 1) oscillator. A high overall cooling effectiveness is observed for sweeping jets with a jet spacing of P/D = 4. Since the high jet pitch (P/D = 6) corresponds to a largely spaced oscillator, the interactions between the adjacent jets are less dominating thus reduce the cooling performance. Overall cooling performance tends to deteriorate with increases freestream turbulence. The pressure drop for a sweeping jet is smaller than the steady jet at the corresponding mass flow rates.

Hossain, M.A., Agricola, L.M., Ameri, A., Gregory, J., Bons, J.P., "Sweeping jet impingement cooling on a simulated turbine vane leading edge," 2018, Global power and propulsion conference, Montreal, Canada. Paper number: GPPS2018-0148.
Hossain, M.A., Agricola, L.M., Ameri, A., Gregory, J., Bons, J.P.,"Sweeping jet impingement cooling on a simulated turbine vane leading edge,"GPPS2018-0148, Global power and propulsion journal, 2:402-414. [pdf]

Curvature Effect on Sweeping Jet Impingement

A numerical investigation is conducted to evaluate the effect of curvature on sweeping jet impingement heat transfer performance. A conventional fluidic oscillator with an aspect ratio of unity is used to produce the sweeping jet. Three configurations differing in the radius of curvature of the impingement surface are studied for both steady and sweeping jets at three jet-to-wall spacing (H/D = 3, 5 and 8). The radius of curvature is normalized by throat hydraulic diameter (Dh). The first case (case A) has a flat impingement surface where the radius of curvature is infinity. The next two cases have moderate and high surface curvature with radius of curvatures of 20Dh (case B) and 10Dh (case C) respectively. Unsteady RANS simulations were performed to evaluate the external flow field and heat transfer performance. Numerical results are validated by both oscillation frequency and local Nusselt number distributions obtained from experimental measurement, and show good agreement. Time averaged and time resolved flow fields and heat transfer results are presented. Results shows heat transfer augments with surface curvature for steady jet. However, the sweeping jet does not show a monotonic behavior with surface curvature. The most effective Nu-distribution is found in moderate curvature (case B), where the radius of curvature is 20Dh as the jet remains normal to the impingement wall during oscillation.

Hossain, M.A., Agricola, L.M., Ameri, A., Gregory, J., Bons, J.P., "Effects of Curvature on the Performance of Sweeping Jet Impingement Heat Transfer," 56th AIAA Aerospace Sciences Meeting, 2018, Florida. [pdf]

Flat Plate (R = infinity)

Moderate curvature (R = 20D)

High curvature (R = 10D)

Fan Angle effect on Sweeping Jet Impingement Cooling

Numerical investigations were performed to evaluate the effects of sweeping jet exit fan angle on the impingement heat transfer performance. A conventional wall attachment type fluidic oscillator with an aspect ratio (AR) of unity was used to generate the sweeping jet. Eight different exit fan angles ( ) were studied at three jet-to-wall spacings (H/D=3, 5, 8) and three coolant massflow rates ( 50, 75, 100 slpm). Unsteady RANS simulations were performed to evaluate the external flow field and heat transfer performance. Numerical flow field and heat transfer results were validated by comparing the oscillation frequency and surface Nusselt number (Nu) distribution to experimental measurements. Time-averaged flow field and heat transfer results are presented for different exit angle configurations. A new cooling uniformity index ( ) is defined to evaluate the heat transfer uniformity for the sweeping jet. Results show a significant effect of exit fan angle on local surface Nu distribution for an impinging sweeping jet. The sweeping action of the jet augments local turbulence in the jet shear layer and heats up the core flow as it interacts with the target wall, resulting in a drop in local Nu compared to a steady jet. Time-averaged flow field results showed separated flow at large exit fan angles. Numerical calculations were performed to estimate the discharge coefficient of the sweeping jet at different exit angles.

Hossain, M.A., Agricola, L.M., Ameri, A., Gregory, J., Bons, J.P., "Effects of Exit Fan Angle on the Heat Transfer Performance of Sweeping Jet Impingement," 2018 International Energy Conversion Engineering Conference, AIAA Propulsion and Energy Forum, Cincinnati, Ohio. (AIAA 2018-4886). [pdf]

Crossflow Interaction of Oscillating jet

Numerical investigations were conducted to evaluate the interaction of an oscillating jet with a crossflow. A conventional curved fluidic oscillator with an aspect ratio of unity is used. The flow interaction is investigated at three different inclination angles to the crossflow free stream direction and at three blowing ratios, An Unsteady Reynolds Averaged Navier-Stokes (URANS) model was used to evaluate the flowfield. Models were validated by comparing key flow features and oscillating frequency reported in the literature. Time averaged and time resolved flow fields are presented. Two alternating streamwise vortices are observed at all blowing ratios. The sense of rotation of these alternating vortices is opposite to the traditional counter rotating vortex pair (CRVP) found for a steady jet in crossflow.

Hossain, M.A., Prenter, R., Lundgreen, R.K., Agricola, L.M., Ameri, A., Gregory, J., Bons, J.P., 2017, " Investigation of crossflow interaction of an oscillating jet," 55th AIAA Aerospace Sciences Meeting, AIAA 2017-1690. [pdf]

Roughness effect on Fluidic Oscillator

An experimental investigation is conducted to evaluate the effects of roughness on the performance of a fluidic oscillator. A conventional curved fluidic oscillator with an aspect ratio of one is used for this study. Two different sandpapers (Ra= 25.28µm, 46.54µm) are used to create an artificial roughness on the walls of the fluidic oscillator. Several roughness and blockage configurations have been studied including rough top and bottom walls, rough feedback channels and rough main mixing channel. Oscillation frequency is measured with a microphone at several mass flow rates. The spreading angle of the jet is measured by a constant temperature anemometry (CTA) hotwire. Schlieren imaging technique is used to observe the external flow field of both smooth and rough oscillators.It has been observed that added roughness on the top and bottom walls of the device decreases the overall cavity depth resulting in an augmentation of effective aspect ratio, which increases the oscillation frequency of the jet. However, added roughness at the main mixing channel has a detrimental effect on the performance of the device. After a certain mass flow, the jet stops oscillating due to increased blockage at the main mixing channel. Very little effect on the oscillation frequency has been observed for the rough feedback channel. Unsteady RANS calculations are performed for two blockage configurations to understand the internal and external flowfield caused by the blockage.

Hossain, M.A., Prenter, R., Lundgreen, R.K., Agricola, L.M., Ameri, A., Gregory, J., Bons, J.P., 2017, " Effect of roughness on the performance on fluidic oscillator," 55th AIAA Aerospace Sciences Meeting, AIAA 2017-0770. [pdf]

Fluidic Oscillator Flow field

Development of 3D printing technology has enabled the implementation of innovative cooling architecture inside a turbine blade. The fluidic oscillator is such a promising device which can be used for both unsteady impingement and sweeping film cooling application. The general working principle of such a device is quite simple and involves no moving parts. When a jet enters into the cavity from a pressurized plenum via the power nozzle, two opposite vortices begin to form on both sides of the power jet. As the intensity of the vortices increase, one vortex becomes dominant. This causes the power stream to deflect against the opposite wall and attached to the side wall due to the Coanda effect. This allows a portion of the fluid to enter into the feedback loop which flows back to the control port and causes the power stream to detach from the side wall. The power stream then switches to the opposite wall and the same process repeats, resulting in an oscillatory fluid motion at the throat. A full-scale 3D CFD analysis is being performed in order to predict the internal flow and external flow field of the fluidic device. The commercial solver FLUENT is being used for the numerical calculation.

Flow control of a Transonic LPT blade

An experimental investigation is conducted to evaluate the effects of freestream turbulence on separation control with steady vortex-generator jets (VGJs) on a highly loaded transonic low-pressure turbine (LPT) cascade. A compressible LPT profile is tested in a high-speed linear cascade facility that exhibits shock induced separation at Mach number of 0.8. A span wise row of discrete vortex-generator jets is implemented at 60% chord on the suction surface for an active flow control. Baseline transonic conditions are obtained at an inlet Mach number of 0.43 and Reynolds number of 850,000 based upon axial chord of 60mm. Isentropic Mach number distribution and wake total pressure loss are estimated for baseline performance at different operating conditions. Comparisons are made between baseline results and previously published results in the same facility. Square mesh grids of three different blockage ratios are introduced upstream of the flow in order to vary the freestream turbulence (FST) intensity. The present study investigates the effectiveness of VGJs at different freestream turbulence level. It has been observed that higher FST reduces the effectiveness of VGJs. This is due to a rapid transition from a laminar to turbulent boundary layer on the blade suction surface. In addition, higher blowing ratio (B = jet velocity/freestream velocity) exhibits rapid dissipation of the spanwise vortices and results in an overall reduction of effectiveness of VGJs.

Sacco, C., Hossain, M.A., Bons, J.P., “The effect of freestream turbulence on Steady VGJ Flow Control on a Highly Loaded Transonic LPT Cascade,” AIAA Aviation 2016, Washington, DC, USA. Paper number: AIAA-2016-4089. doi: 10.2514/6.2016-4089

Flow Measurement of a Pulsed Jet

To determine the air pressure on the cornea, the spatial and temporal profiles of the air puff were measured by hot wire anemometry in the xy and xz planes. A photocell sensor was installed at the outlet of the nozzle to synchronize measured velocity data and the pressure signal produced by the Corvis ST. Hot wire calibration was done with a 1.5mm orifice in order to replicate the actual flow condition in the subsequent experiments. Data were acquired at a sampling rate of 20kHz, from 0 to 16mm from the nozzle in 2mm increments in the axial direction and in .75mm increments up to 3mm on each side of the centerline, for a total of 81 individual points with 40 individual puffs for each data point. The characterization of the air puff demonstrated that the velocity time history at a single location remained consistent for all 40 puffs that were measured, and the flow was also verified to be axisymmetric. This velocity was converted to a dynamic pressure using the ambient density. (click the image for animation)

Roberts CJ, Mahmoud AM, Bons J, Hossain A, Elsheikh A, Vinciguerra R, Vinciguerra P, Ambrósio R., 2016, “A New Stiffness Parameter in Air Puff Induced Corneal Deformation Analysis”. Invest Ophth Vis Sci. 2016; 57: ARVO (Association for Research in Vision and Ophthalmology)
Roberts C, Mahmoud A, Bons J, Hossain A, Elsheikh A, Vinciguerra R, Vinciguerra P, Ambrósio R., “Introduction of Two Novel Stiffness Parameters and Interpretation of Air Puff–Induced Biomechanical Deformation Parameters With a Dynamic Scheimpflug Analyzer,” J Refract Surg. 2017; 33: 266-273. doi: 10.3928/1081597X-20161221-03

Design of a High-Intensity Turbulent Combustor

The work is focused on design and development of a combustion system for flow in compressible, turbulent, and premixed conditions. An air-methane mixture has been selected as the fuel for this study where the system is composed of three main subsystems: the air handling and preparation, instrumentation and controls, and the combustor. A backward-facing step flame stabilization method and optical accessibility features for flow diagnostics were the main drivers for the combustor design, which was sized for compressible flow (M > 0.3), and a maximum operating pressure of 6 bar. A grid, or perforated plate, of different hole diameters and blockage ratios is used as the turbulence generator for the experiment. Optical access to the chamber is provided via the use of quartz windows on three sides of the combustion chamber. In order to increase the inlet temperature of the air, a heating section was designed to use commercially available in-line heaters. Finally, a LabVIEW software interface has been selected as the control mechanism for the experimental setup.Preliminary understanding of the flow field inside the combustor was achieved through the use of Detached Eddy Simulation (DES) analyses for fluid flow. Finite Element Analysis (FEA) is done in order to verify the structural integrity of the combustor at rated conditions. Preliminary validation is done by 10kHz time resolved Particle Image Velocimetry (TR-PIV) technique. Turbulent intensity and vorticity are calculated by DES simulation and PIV results are compared with CFD and presented.

Arturo Acosta, M. A. Hossain, Marco Quiroz, Ahsan Choudhuri, Design of A High Turbulence Intensity Combustion System ,50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibition, Cleveland, Ohio. doi: 10.2514/6.2014-3874
Hossain, M.A., Love, N.D., Choudhuri, A., 2017 “Design of A High Turbulence Intensity Combustion System”, Journal of Mechanical Engineering Science, JMES-17-1014, DOI: 10.1177/0954406218757565

NOx Emission of Syngas Combustion

Integrated Gasification Combined Cycle (IGCC) is a gasification process that is used to produce syngas from variety of fossil fuels, including coal, biomass, organic waste, and refinery residual. It contains variable composition of CO and H2. Because of its wide fuel flexibility, the syngas is considered as most effective fuel particularly for power generation purposes. These types of high hydrogen content fuel faces a great difficulty to lower the NOx emission due to its high flame speed, low ignition energy can cause flashback. This paper is focused on the syngas combustion along with the NOx emissions for different equivalence ratios for a multi-tube injector inside a gas turbine combustion chamber. This paper describes the numerical study of the emissions of nitrogen oxides (NOx) for perfectly premixed combustion using CFD combustion modeling. In this study CO+H2 is mixed with air in lean equivalence ratio. The CFD Eddy Dissipation model is used to study the perfectly premixed combustion. Commercial software ANSYS Fluent has been used for CFD analysis. The Eddy Dissipation model is best for turbulent flows when the chemical reaction rate is fast relative to the transport processes in the flow. There is no kinetic control of the reaction process. The Eddy Dissipation model is sufficient enough for the combustion process if air and fuel is available in a control volume.Hossain, S.,

Hossain, M.A., “Numerical Investigation of Perfectly Premixed Combustion and the Effect of NOx Emission for Syngas in a Gas Turbine Combustor,” ASME 2015 Power conference, San Diego, California, USA. Paper number: POWER2015-49388, doi:10.1115/POWER2015-49388

Shock Propagation (NREL Phase VI airfoil)

The work is focused on numeric analysis of compressible flow around National Renewable Energy Laboratory (NREL) phase VI wind turbine blade airfoil S809. Although wind turbine airfoils are low Reynolds number airfoils, a reasonable investigation of compressible flow under extreme condition might be helpful. A subsonic flow (mach no. 𝑀 = 0.8) has been considered for thisanalysis and the impacts of this flow under seven different angles of attack have been determined.The results show that shock takes place just after the mid span at the top surface and just before the mid span at the bottom surface at zero angle of attack. Slowly the shock waves translate their positions as angle of attack increases. A relative translation of the shock waves in upper and lower face of the airfoil are presented. Variation of Turbulent viscosity ratio and surface Y+ have also been determined. A k-𝜔 SST turbulent model is considered and the commercial CFD code ANSYS FLUENT is used to find the pressure coefficient (Cp) as well as the lift (CL) and drag coefficients (CD). A graphical comparison of shock propagation has been shown with different angle of attack. Flow separation and stream function are also determined.

M. A. Hossain, Ziaul Huque, and Raghava R. Kammalapati, Propagation of Shock on NREL Phase VI Wind Turbine Airfoil under Compressible Flow, Journal of Renewable Energy, vol. 2013, Article ID 653103, 2013. doi:10.1155/2013/653103
M. A. Hossain, Ziaul Huque, Raghava R. Kammalapati, Shubarna Khan, Numeric Investigation of Compressible Flow Over NREL Phase VI Airfoil, International Journal of Engineering Research and Technology (IJERT), ISSN: 2278-0181,Vol 2 Issue 2, 2013

Fluid-Structure Interaction on a Wind Turbine Blade

The work is focused on numeric modeling of aerodynamic load developed on a wind turbine blade and its effects on aeroelastic characteristics of a wind turbine blade. In order to do that proper turbulent model along with appropriate assumptions need to be determined. Geometry is modeled with actual blade data for both twist and tapper. Blade tip is not considered during the modeling. Validation is done by NREL phase VI wind turbine blade data as well as other published data. Finally the aerodynamic load obtained from the CFD simulation is transferred to perform the structural analysis. It has been found that the load distribution along the blade span is not linear. It varies with the span length and it also varies along the chord of the blade airfoil. Due to this varying load the stresses developed in the blade is dissimilar which dictates the skin thickness of the blade and the shape of the spur inside the blade. It has also been observed that the aerodynamic characteristics such as lift coefficient (CL) and pressure coefficient (CP) changes with the deflection of the blade which affects the power output of the wind turbine.M. A. Hossain, Sarzina Hossain, Shakerur Ridwan, 'Numeric Investigation of Fluid Solid Interaction and performance analysis of pre-bent Wind Turbine Blade, 'Proceeding of ASME 2014 International Mechanical Congress and Exposition IMECE 2014, Paper number: IMECE 2014-37394.doi:10.1115/IMECE2014-37396

M A. Hossain, Ziaul Huque, Raghava R. Kammalapati , 'Numeric Investigation of Fluid-Solid Interaction on Wind Turbine Blade, Proc. ASME 56383; Volume 9: Mechanics of Solids, Structures and Fluid, V009T10A004, November 15, 2013, Paper number: IMECE 2013-65647, doi:10.1115/IMECE2013-65647

Porous Medium Heat Transfer (Numerical Analysis)

This work deals with numerical investigation of porous medium heat transfer for square tube cross flow heat exchanger. The simulation is done for 2D turbulent flow. In order to resolve the flow field, Reynolds Average Navier-stokes (RANS) model is used. Standard k-epsilon model is considered among different RANS model in order to resolve the mean velocity field, pressure drop and temperature distribution. Both average velocity, temperature distribution and pressure drop are calculated for three different cases having three different porosity (ϕ), permeability (K) and inertial coefficient (β). The results of three different cases are compared and presented. First the mesh independence test is done by different mesh size. ANSYS Fluent is used for the simulation. A pressured based solver is used with SIMPLE solution scheme, in order to find different flow variables. Finally the Nusselt number (Nu) and surface heat transfer coefficient (h) are determined and presented.

M. A. Hossain, Sarzina Hossain, 'Numerical Investigation of Porous Medium Heat Transfer, 'Proceeding of ASME 2014 International Mechanical Congress and Exposition IMECE 2014, Paper number: IMECE 2014-37387. doi:10.1115/IMECE2014-37387

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