Session: 12-12-01: Gas Turbine Heat Transfer and heat exchanger

Paper Number: 171608

Evaluating Film Cooling Effectiveness With Vortex Generators 

        Film cooling is a widely employed technique in modern gas turbines to protect high-temperature components such as turbine blades and vanes from thermal degradation caused by exposure to hot combustion gases. As turbine inlet temperatures continue to rise to meet the demands for increased thermal efficiency and reduced emissions, effective cooling strategies become indispensable. Film cooling operates by introducing a layer of cooler air through holes in the component surface, creating a protective film that insulates the metal from the hot mainstream flow. The effectiveness of this technique, however, is limited by the complex interactions between the coolant jet and the mainstream flow, particularly the formation of counter-rotating vortex pairs (CRVP).
    
    CRVPs arise due to jet bending in the cross-flow direction, which leads to the lifting of the coolant away from the surface. This jet lift-off results in a significant reduction in cooling effectiveness and deteriorates the thermal protection of the surface. As a result, a substantial amount of coolant is wasted, and the reliability of the component is compromised. These effects are particularly pronounced at high blowing ratios, where the jet momentum dominates and further promotes separation from the surface.
    
    To overcome these challenges, the present study proposes a novel film cooling configuration that combines Anti-Vortex Holes with Micro Ramps (AVH-MR). This innovative design aims to counteract the negative impact of CRVPs by modifying the vortex dynamics near the coolant injection site. The micro ramps are strategically positioned to generate anti-counter-rotating vortex pairs (ACRVPs), which oppose the formation of traditional CRVPs and help in maintaining the coolant film close to the surface. 
    
    Comprehensive three-dimensional numerical simulations were carried out using OpenFOAM, an open-source computational fluid dynamics (CFD) platform. The simulations employed the Shear Stress Transport (SST) k-w turbulence model, which is well-suited for predicting near-wall flow behavior and turbulent mixing. The analysis considered a range of blowing ratios (B = 0.5, 1.0, and 1.5) while keeping the density ratio constant (DR = 1.0) to isolate the influence of blowing strength on cooling performance.
    
    The simulation results showed excellent correlation with existing experimental data, validating the accuracy and reliability of the numerical setup. The AVH-MR configuration demonstrated a marked improvement in cooling effectiveness compared to a conventional baseline design. Specifically, cooling effectiveness improved by up to 20\% at higher blowing ratios and by approximately 12.86\% at lower blowing ratios. This enhancement is attributed to improved lateral spreading of the coolant and better surface attachment, facilitated by the generation of ACRVPs from the micro ramps.
    
    In addition to performance improvements, the AVH-MR configuration also showed a more uniform coolant distribution and reduced peak surface temperatures. These characteristics are particularly beneficial for extending component life and reducing thermal fatigue. Furthermore, by improving coolant utilization, this design can potentially reduce the amount of air bled from the compressor for cooling, thereby increasing the overall cycle efficiency of the gas turbine.
    
    In conclusion, the AVH-MR film cooling strategy presents a promising solution to the limitations of conventional cooling methods. Its ability to mitigate CRVP-induced jet lift-off and enhance surface film coverage makes it a strong candidate for future high-performance gas turbine applications. The findings from this study offer valuable insights into advanced cooling design and provide a solid foundation for further experimental validation and optimization in real engine environments.

Presenting Author: Ilyes Belouddane University of Science and Technology of Oran Mohamed Boudiaf

Presenting Author Biography: Dr. Ilyes Belouddane is a mechanical engineer and researcher with expertise in thermal-fluid systems and computational fluid dynamics (CFD). He earned his Ph.D. in Mechanical Engineering from the University of Science and Technology of Oran - Mohamed Boudiaf (USTO-MB), Algeria. His doctoral research centered on enhancing turbine blade cooling efficiency through advanced film cooling techniques, including micro-ramps and anti-vortex hole configurations.
Dr. Belouddane has substantial experience using CFD tools such as OpenFOAM and ANSYS CFX for simulating and optimizing cooling systems in gas turbines. He currently serves as a Mechanical Technician at SONATRACH GL2/Z, where he supports the operation and maintenance of complex gas processing infrastructure.
His research interests span heat transfer enhancement, jet-in-crossflow behavior, turbine blade cooling, and the design of advanced cooling strategies for aerospace and power generation systems. Dr. Belouddane is the lead author of several technical publications and is actively pursuing academic and research positions in North America in the fields of mechanical and aerospace engineering.

Authors:

Ilyes Belouddane University of Science and Technology of Oran Mohamed Boudiaf