Fluid-Structure Interaction Analysis of Aircraft Hydraulic Pipe with Complex Constraints Based on Discrete Time Transfer Matrix Method

Abstract

Fluid-structure interaction (FSI) is prevalent in aircraft hydraulic pipes due to high-pressure fluid pulsation, complex pipe path routing and boundary constraints, which pose a serious threat to the safety and reliability of the aircraft hydraulic system. This paper focuses on the FSI response of aircraft hydraulic pipes with complex constraints. A comprehensive fourteen-equation model for describing the FSI of pipe conveying fluid with wide pressure and Reynolds number range is proposed. The excitation models and complex boundary constraints of liquid-filled pipes are established. Moreover, based on the transfer matrix method (TMM), combined with the time discreteness and analytical integral method, a discrete time transfer matrix method (DTTMM) for solving the FSI fourteen-equation model in time domain is presented. Then, the numerical solution and experiment of an ARJ21-700 aircraft hydraulic pipe with complex constraints is carried out with four working conditions. The obtained results verify the correctness of the proposed model and solution method, and reveal the universal laws of the FSI response about aircraft hydraulic pipes, which can also provide theoretical and experimental references for modeling, solutions and verification in the FSI analysis of pipe conveying fluid.

Frequency Domain Analysis of Fluid–Structure Interaction in Aircraft Hydraulic Pipe with Complex Constraints

“…Fourteen partial differential equations that describe the pipe conveying fluid (Figure 1) were established based on the acoustic wave equation and Timoshenko beam dynamic model, which describe the fluid dynamics and axial/flexural/torsional motions of the pipe in three-dimensional space, thus basically containing two equations of fluid motion and three sets of twelve equations of pipe motion. The fundamental assumptions and applicable conditions of the governing equations refer to the published literature [1].…”

“…Considerable research regarding the FSI nonlinear dynamics characteristics of aircraft hydraulic pipes has been reported in the past years [1][2][3][4][5][6][7][8][9][10][11][12]. The precondition for analyzing these dynamic behaviors was to establish an accurate mathematical model.…”

“…Then, the fourteen-equation model was extended and widely used by many scholars [21][22][23][24] for modelling fluid pulsation, Poisson coupling, friction coupling, junction coupling, deformation of the pipe in various directions, extra mass, springs, and various complex boundary conditions. Moreover, the fourteen-equation model has been applied to the analysis of some complex engineering environments [1,4,10,23,25], and it has become the most systemic model at present. Notably, Tan et al [26] found that Timoshenko beam theory is more suitable for studying the vibration characteristics of pipes conveying high-speed fluid.…”

“…In the above-mentioned models, only semi-analytical or numerical methods can be used for solving; the representative methods are as follows: method of characteristics (MOC) [14,[27][28][29][30], finite element method (FEM) [31][32][33], MOC-FEM [34,35], and transfer matrix method (TMM) [1,4,10,21,[23][24][25][36][37][38][39]. MOC and MOC-FEM are especially used for fluid transient response analysis in the time domain, while FEM and TMM are widely used for forced vibration response in the frequency domain [1]. FEM is the most common method for analyzing complex pipe structures; however, FEM requires a better quality mesh to ensure solution precision at high frequencies [3], which will consume a lot of computing time and memory resources [36].…”

“…The application range of various types of models and simulation algorithms of fluid-filled pipe systems that considered the FSI in the frequency domain were compared and discussed. Based on the transfer matrix method, the Yanshan University research team [1,4,10,25] carried out theoretical research and experimental verification of FSI vibration of aircraft hydraulic pipes, which broadens the application range of the transfer matrix method in engineering practice. From the above review, it can be seen that TMM has been widely used in the vibration problems of pipes conveying fluid, due to its good adaptability, compared with other solution methods.…”