The aerodynamic and thermal behaviour of multiperforated zones in combustors is essential to the development of future combustion chambers. Detailed databases are therefore essentialcrucial for the validations of RANS/LES solvers, but also regarding the derivation of heat transfer correlations used in 0D/1D in-house codes developed by engine manufacturers.  
To the best of our knowledge, there is not study in the literature currently presenting a combined fluid dynamics/heat transfer detailed database of the flow encountered around a multiperforated plate for anisothermal conditions and a 90° compound injection. In the framework of FP7 EU SOPRANO Program, the test-rig used in a previous study was modified to be compatible with anisothermal conditions. The injection has been modified to integrate a heating system to generate a moderate temperature gradient of about 20 K between the secondary flow (injection) and main flow. A honeycomb and insulating material have been integrated in the secondary channel to generate a well-controlled inlet condition. All instrumentation for the acquisition of flow conditions (mass flow rate, temperature, pressure) has been calibrated and connected to a dedicated acquisition system. The aerodynamic field is acquired by a PIV 2D-3C (Particle Image Velocimetry) system. It is installed around the test-rig with a displacement system to be able to make detailed analysis of the flow along the 12:1 scale multiperforated plate. The flow temperature is acquired by a DANTEC cold-wire thermometry system, by exploring several planes along the first rows of holes. The surface heat transfer coefficient is derived based on surface temperature distribution acquisitions. Those temperature distributions are obtained via infrared thermography measurements with a FLIR SC7600 camera. The extra heating required to generate a heat transfer through the plate is provided by an electrical conductive paint on the cool surface. Several heating power levels are tested, which allows to evaluate the convective heat transfer coefficient and reference temperature through a linear regression. Measurements are conducted on both sides of the plate, which also gives access to those quantities on the injection side.  
From a numerical point of view, the configuration is studied using the unstructured ONERA in-house CEDRE solver. Turbulence is modelled using the classical Menter k-w SST model, and two calculations (one adiabatic, one isothermal) are carried out to estimate the appropriate data. A systematic comparison is presented between the experimental and numerical database.  
PIV maps are presented in the directions normal to the flow as well as normal to the wall. This allows to follow the main cold freestream and the hot jets issued from the holes. The analysis of this database shows a flowfield and heat transfer strongly varying with the axial location. No asymptotic behaviour is obtained for the heat transfer coefficient. PIV/CFD results confirm the 3D character of the flow. The compound injection creates a massive lateral movement of the flow, which combines with the main freestream component, and interacts with the side walls of the test rig. Even if this flow differs from the one encountered in combustion chambers, which are most often tubular, most regions offer a clear view of the interaction between the jets and mainstream, for a 90° side injection. The flows issued from the various holes interact to create a protection film in a complex pattern, revealed by the convective heat transfer coefficient map. In regions where the mainstream is diminished by the lateral movement, this heat transfer decreases. The agreement between experimental and CFD results is judged satisfactory.  

 


A Combined Experimental and Numerical Characterization of the Flowfield and Heat Transfer Around a Multiperforated Plate With Compound Angle Injection

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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