Damage-Mitigating Control of a Reusable Rocket Engine

This article presents a control concept for damage prediction and damage mitigation in reusable rocket engines for enhancement of structural durability. The key idea here is to achieve high performance without overstraining the mechanical structures so that 1) the functional lives of critical components are increased, resulting in enhanced safety, operational reliability, and availability; and 2) the plant (i.e., the rocket engine) can be inexpensively maintained, and safely and efficiently driven under different operating conditions. To thiseffect, dynamics of fatigue damage have been modeled in the continuous-time setting instead of the conventional cycle-based approach, and an optimal control policy is formulated by constraining the accumulated damage and its time derivative. Efficacy of the proposed damage mitigation concept is evaluated for life extension of the turbine blades of a bipropellant rocket engine via simulation experiments. The simulation results demonstrate the potential of increasing the structural durability of reusable rocket engines with no significant loss of performance.