Session: 15-01 Jet Impingement

Paper Number: 81749

81749 - Assessment of Computational Fluid Dynamic Modeling of Multi-Jet Impingement Cooling and Validation With the Experiments 

The impingement jet cooling is extensively used in gas turbine engines and is characterized by complex aero-thermodynamic phenomena. Consequently, an accurate prediction of the heat transfer is required to determine the optimized amount of coolant. The current study involves numerical and experimental investigations of circular in-line jets impinging on a heated flat plate. The generic configuration is characterized by 9 jets, each with a diameter of D=0.0152 m. The jets are influenced by a self-generating cross-flow and are positioned at a nozzle-to-plate distance (H/D) of 5 and a jet pitch (p/D) of 5. The steady Reynolds-Averaged Navier-Stokes (RANS) simulations are performed for turbulent jet Reynolds numbers with the DLR in-house CFD code TRACE. The Menter SST model is applied for turbulence modeling and the turbulent scalar fluxes are modeled based on the Reynolds analogy for a constant turbulent Prandtl number.

To gain a closer insight into the impingement jet physics, high-resolution near-wall velocity and thermal fields are obtained through Large Eddy Simulations (LES) and experiments. The focus is laid on the comparison of RANS results with the LES data and the measurement data from Particle Image Velocimetry (PIV), Temperature Sensitive Paint (TSP), and Pressure Sensitive Paint (PSP). The results exhibit a qualitative similarity amongst the simulations and the experiments. The flow in the critical regions such as a sudden change of the cross-sectional area, the shear layers, the jet-to-jet collisions, and the jet stagnation regions is considered to evaluate and quantify the heat transfer and velocity field prediction errors. Furthermore, correlations of the Nusselt number from the literature are used to validate the simulation results. Recommendations are provided to obtain satisfactory results from RANS simulations with optimized computational power requirements.

The heat transfer phenomenon for different thermal boundary conditions on the heated plate is analyzed. The variation of velocity profiles in the pipes due to inlet filleting and its effect on heat transfer is studied. The turbulence modeling is modified by the usage of Langtry and Menter two-equation transition model and the Kato-Launder production limiter. As a result, the prediction of the Nusselt number in the jet stagnation regions is enhanced. Additionally, the modification of convective heat transfer due to the conduction in the solid is studied by performing a Conjugate Heat Transfer (CHT) simulation. The CHT simulation revealed a strong two-way coupling of heat transfer in the solid and the fluid domains.

Presenting Author: Sadiya Tabassum German Aerospace Center (DLR)

Presenting Author Biography: Since 2020: Research Associate at the German Aerospace Center (DLR)<br/>Topic: Turbine Blade Cooling, Secondary Air System and CFD.<br/><br/>2017-2019: Master of Science in Aerospace Engineering, Aachen, Germany<br/>Thesis: Flow simulation around isolated two-wheel main landing gear<br/><br/>2012-2016: Bachelor of Technology in Aeronautical Engineering, Hyderabad, India<br/>Thesis: Fluid-Structural coupling of a hypersonic vehicle structure

Authors:

Sadiya Tabassum German Aerospace Center (DLR)
Robin Georg Anthony Brakmann German Aerospace Center (DLR)
Michael Hilfer German Aerospace Center (DLR)
Marcel Matha German Aerospace Center (DLR)
Christian Morsbach German Aerospace Center (DLR)
Michael Markus Manfred Schroll German Aerospace Center (DLR)
Christian Willert German Aerospace Center (DLR)