Blocker-less Engine Thrust Reverser (BETR)

In this study, a systematic parametric optimization of the blockerless engine thrust reverser (BETR) was performed using analytical and computational analysis. The effectiveness of an alternative blocking mechanism for the fan flowing the form of a high momentum fluid injection was thoroughly investigated. Trajectory based computational analysis was performed for the actual BETR system on a sub-scale model similar to that used in the experimental studies. The design parameters tested in this study were the injection location X, injection angle θ, and injection slot thickness t. Similarly, the operational parameters studied were the cascade opening S and fan flow rate Wf. It was shown that the injection location and injection angle play a vital role in determining the optimum injection requirements for cascade flow saturation. It was observed that the axial locations corresponding to X∕H 0.0 required the lowest injection percentages. Similarly, core injections directed upstream showed significant performance improvement. For smaller injection angles, it was observed that the jet deflected toward the neighboring wall due to jet–wall interaction. This phenomenon allowed deeper penetration of the jet stream into the cross-flow. Injection slot thickness governs the momentum of the jet entering the cross-flow, and thus smaller thickness leads to better performance. However, if the injection slot thickness is reduced up to the point of choking, the performance characteristics do not change any further. The cascade slot opening determines the clearance angle required by the jet trajectory in order to clear the trans cowl. For smaller openings, this angle is higher, and thus higher injection rates are required for cascade flow saturation and vice versa. Lastly, it was observed that the fan flow rate had no significant impact on the performance. The results of this computational study are in accordance with the experimental results of Tindell et al.