Chuanzhi Sun, Danyang Chen, Chengtian Li, Yongmeng Liu, Zewei Liu, Ming Hu and Jiubin Tan
This paper aims to provide a precision assembly method to improve the aircraft engine quality of initial unbalance with the purpose of founding the process for mass eccentricity…
Abstract
Purpose
This paper aims to provide a precision assembly method to improve the aircraft engine quality of initial unbalance with the purpose of founding the process for mass eccentricity propagation and demonstration of assembly process. The proposed method can be used for assembly guidance, tolerance allocation and so on, especially for the assembly with a large number of rotors and the assembly requirements of initial unbalance and coaxiality in high precision.
Design/methodology/approach
This paper proposes a constrained optimization-build method to minimize initial unbalance of aircraft engine assembly, which takes amount of unbalance and concentricity of each rotor into account. A constrained nonlinear programming model is extracted by choosing the initial unbalance as the objective function, and choosing the coaxiality and assembly orientations as the nonlinear constraints. The initial unbalance is reduced stage-by-stage by controlling the assembly angle of each rotor.
Findings
The validity and accuracy of the proposed method is verified by the multistage rotors assembly through experiments run with the measuring instruments. Compared with the direct-build method, the initial unbalance of final assembly using proposed method is reduced by 22.2% in four rotors assembly.
Originality/value
Different from the geometric eccentricity propagation control methods to reduce the initial unbalance indirectly, this paper establishes mass eccentric propagation model in multistage rotors assembly of aircraft engine for the first time. It provides a new idea to establish the relationship between the amount of unbalance of each rotor and the initial unbalance of multistage rotors.
Details
Keywords
This paper aims to explore the effectiveness and mechanism of a droplet-laden flow in a microfluidic system.
Abstract
Purpose
This paper aims to explore the effectiveness and mechanism of a droplet-laden flow in a microfluidic system.
Design/methodology/approach
Numerical approach based on the volume of fluid method is implemented for modelling the forced heat transport in a droplet-laden flow in a microchannel.
Findings
The heat transfer effectiveness of droplet-laden flow is found to be obviously superior to that of a single-phase flow because of the circulation stream between the droplets. In addition, the effectiveness will be further increased when an elongated droplet is being laden because the circulation streams within and between the droplets are more pronounced. The elongated droplet size affects the heat transfer characteristics signified by Nusselt number, and there exists an optimum value at a fixed parameter.
Originality/value
This paper attempts to clarify the influence on the heat transfer performance when droplet with various shape and size being laden. This work is done by none before. This research work applies a solid foundation for designing a cooling system in microelectromechanical system.