Fault diagnostics and prognostics for large segmented SRMs

Abstract

We report progress in development of the fault diagnostic and prognostic (FD&P) system for large segmented solid rocket motors (SRMs). The model includes the following main components: (i) 1D dynamical model of internal ballistics of SRMs; (ii) surface regression model for the propellant taking into account erosive burning; (iii) model of the propellant geometry; (iv) model of the nozzle ablation; (v) model of a hole burning through in the SRM steel case. The model is verified by comparison of the spatially resolved time traces of the flow parameters obtained in simulations with the results of the simulations obtained using high-fidelity 2D FLUENT model (developed by the third party). To develop FD&P system of a case breach fault for a large segmented rocket we notice [1] that the stationary zero-dimensional approximation for the nozzle stagnation pressure is surprisingly accurate even when stagnation pressure varies significantly in time during burning tail-off. This was also found to be true for the case breach fault [2]. These results allow us to use the FD&P developed in our earlier research [3]-[6] by substituting head stagnation pressure with nozzle stagnation pressure. The axial corrections to the value of the side thrust due to the mass addition are taken into account by solving a system of ODEs in spatial dimension. 1

Mathematical and Critical Physics Analysis of Engineering Problems: Old-New Way of Doing Things

“…The internal ballistics of the SRMs in the presence of the fault can be conveniently described by the following set of stochastic partial differential equations representing conservation laws for mass momentum, and energy of the gas 27,[27][28][29][30][31][32][33]…”

“…Combining the equations of gas dynamics with the dynamics of propellant regression, nozzle ablation, and case breach fault the performance model of the large segmented SRM in the presence of faults can be summarized [29][30][31][32][33] in the set of Eqs. (15) with the conservative variables U and function f (U) given by Eq.…”

“…The heat flow terms due to radiation QR, convection Qc, and burning of the metal surface in the hot gas flow through the hole are given [29][30][31][32]…”

“…To model case breach fault in a large segmented SRM first we have to introduce a parameterization of the fault. It can be shown [29][30][31][32][33] that the fault dynamics is described entirely by the dynamics of the area of the hole A h (t). The actual dynamics of the fault area can be complicated 34 due to e.g.…”

“…FD&P for the Case Breach Fault To infer fault parameters the following quasi-stationary solution [29][30][31][32][33] Notice1 -31 that burning area A b (R(t)) and nozzle throat area A t (t) are determined by measured nozzle stagnation gas pressure p ns . The accuracy of the relation (18) is further improved by introducing the effective burning area A be (R(t)) in the nominal regime.…”