Damage-mitigating control of a reusable rocket engine

Abstract

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 this effect, 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.

Intelligent Life-Extending Controls for Aircraft Engines

“…The concept of life-extending-control (LEC) was originally proposed and demonstrated in simulation for rocket engines in the early 90s [1][2][3][4][5]. The lifeextending-control research for aircraft engines was initiated by NASA in the late 90s [6,7].…”

Life prediction of thermally highly loaded components: modelling the damage process of a rocket combustion chamber hot wall

“…2a) consisting of the m-phase (13)(14)(15)(16)(17)(18)6%wt Zr [18]) and very fine, silver-rich particles with a size of some nanometres are present. In addition, a Widmannstätten like structure is found all over the grains (see Fig.…”

“…As reference, a main stage thrust chamber is chosen that underwent a series of firing tests and was available for destructive metallographic analyses. The simulation methodology applied here is adapted from the work of Armstrong [9] and carried further on in the following aspects: (1) In all aforementioned theoretical works on this topic [1,9,12] and also in more recent contributions [13,14] the choice of the material model was not justified by phenomenological investigations of the behaviour of the applied alloy. In the present work a series of dedicated experiments on specimen level are performed to conclude which material behaviour phenomena are required to be taken into account.…”

“…(2) Due to the high time consumption, 2D finite elements were applied in [1,9,12]. In [13,14] the hot wall was modelled by a sandwich-beam. In the present work, the proposed model is implemented in the 3D finite element framework, so the simulation method can be applied on arbitrary geometry.…”

Damage-mitigating control: an interdisciplinary thrust between controls and material science

“…The concept and configuration of damage-mitigating control ( D M C ) have been introduced in recent papers by Lorcnzo and Merrill (1991b) and Ray et al (1993aRay et al ( , 1993bRay et al ( , 1994 wherc the objective is to achieve high performance without overstraining the mechanical structures in complex dynamic systems. The major benefit of DMC is extension of the functional lives of critical plant components accompanied by enhanced safcty, operational reliability, maintainability and availability.…”