One-Piece Flow Blade Tuning Process

Abstract

Blade tuning is one of the key tasks of the modern aircraft engine design. Generally, a couple of vibration modes of a blade need to be tuned by changing the distribution of its mass and/or stiffness to avoid the resonance at some specified rotating speed. The widely used traditional method for blade tuning is a loop-based process. It requires a number of design iterations between the aero engineer and the structure engineer. It usually takes a few weeks or up to a few months, depending on the experiences of the engineers, to reach an acceptable new design. The uncertainties caused by the non-convergence associated with the loop-based iteration process have led to serious issues for both project management and quality control. To avoid the problem, this paper presents a robust one-piece flow process based on the principle of the set-based concurrent engineering and applying the concept of Lean & DFSS. Following the concept of Lean & DFSS process, the one-piece flow blade tuning starts with defining key parameters and objectives. These parameters consist of a set of design variables relevant to both structure and aero disciplines. The variation range of each parameter is predefined by the manufacture feasibility and the past design experiences. Based on the principles of DOE, only a definite number of FEA models are developed and analyzed. From these analysis results, important parameters are selected and a family of response functions of those concerned objectives is formulated. The achievable ranges of the objectives are well determined accordingly. Guided by these functions, the structure and aero engineers are then able to evaluate instantly any new design from the various combinations of the above-mentioned design parameters. A robust design can be obtained from the given sensitivity of the variance of those design parameters. This methodology can be applied to blade and vane tuning for fans, compressors and turbines alike. In this paper an example of the application of this process is presented for a hollow fan blade tuning, which is accomplished within a week as planned. The methodology can be standardized and used in many other related engineering design processes as well.