An investigation of jet engine test cell aerodynamics by means of scale model test studies with comparisons to full-scale test results

Using a methodology developed for modeling of engine test facilities and simulating turbofan engines, an investigation of large turbofan engine test cell aerodynamics was conducted by means of several scale model studies with comparisons to full-scale test results. The results of the scale model studies were used to determine recommended modifications to existing airline owned and operated test cell facilities which would improve the engine test environment and permit stable, reliable, and repeatable testing capability for the GE CF6-80C2 engine. In all cases, the full-scale test cells after modification met or exceeded the aerodynamic performance goals necessary to achieve the required stable and repeatable engine testing environment. Comparisons were made between the results of the model tests and the results obtained from the full-scale facilities after the modifications to each test cell were completed. Test cell performance parameters compared included front cell velocity, cell airflow, cell bypass ratio, inlet system total loss, cell depression, and bellmouth pressure distortion. Particular emphasis was focused on the ability of the model tests to correctly predict the amount of front cell airflow, and subsequently the cell bypass ratio, for the full-scale test cells.;The model studies conducted as a part of this work have helped bring needed changes to the considerations made in process of test cell design and have provided a solid basis for improved engine test facilities now in use by several airlines. The full-scale results and operational experiences included in this work have served to validate the model test methodology by successfully demonstrating that the implementation in full-scale of recommended modifications based on the model studies resulted in the achievement of specific test cell aerodynamic performance goals and engine parameter variation guidelines. A much improved understanding and heightened awareness of the fundamental importance of the aerodynamics of the large turbofan engine indoor testing environment have resulted in significantly improved engine test facilities now in use world-wide.