Papers by Author: Zhu Feng Yue

Abstract: Anti-lightning strike protection for composite structures is catching great attention to design optimum lightning protection solution. Based on lightning direct effect, optimizations of flame spraying aluminum thickness and composite laminate plies were conducted by combining electrical-thermal analysis procedure and corresponding optimization programs. Optimized thickness was acquired for flame spraying aluminum layer. Meanwhile, non-uniform thick plies and optimized stacking angles were given for anti-lightning strike composite laminate. Comparisons were conducted to investigate changes of lightning direct effects on composite laminates fore and after optimization. Synergetic protections of flame spraying aluminum and laminate plies design were listed. The conclusions can be used as suggestions for lightning strike protection of advanced aircraft.

Abstract: This paper studies the aerodynamic and heat transfer influence of tip structures for cooling turbine blade. Four blades with different tip features are discussed, and coupling aerodynamic and heat transfer method is used to accomplish the simulation. The results show that squealer tip can greatly reduce the heat transfer between tip surface and high temperature gas, and also it reduces tip leakage, to some extent. That’s because it exists obviously eddy near the tip surface. Tip injection holes can cool the tip surface effectively, and it will greatly reduce the temperature of tip surface. However, injection holes improve tip leakage slightly.

Abstract: A numerical based study was conducted to further understanding of turbine tip leakage and flow mechanisms for squealer tip blade. Three blade geometry models with different tips are established. They are squealer tip blade, squealer tip with injection holes blade, squealer tip with injection and film cooling holes blade, separately. Coupled aerodynamic and heat transfer numerical simulation method is used to study blade tip flow and heat transfer based the whole blade computational model. The results show that tip coolant injection will perform a positive effect for the resisting tip leakage, and it will reduce the temperature of blade tip surface and squealer rim, greatly. Film cooling near tip can cool blade squealer rim effectively, but it brings extra total pressure loss.

Abstract: This paper presents the study of the influences of cooling holes on the creep life behavior in the modeling specimen of single crystal cooling turbine blade at high temperature. Thin-walled cylindrical specimens with holes are tested to model the air-cooled turbine blade. Specimens without holes are also studied to make comparisons. Experimental results show that at 900°C, the creep lives of specimens with holes are longer than those of specimens without holes. Scanning Electron Microscopy (SEM) analyses reveal that creep deformations occur firstly around the cooling holes and finally rupture at the region with low stress and strain. Finite element analyses are used to study the creep damage development by a K-R damage model which has been implemented into the Abaqus user subroutine (UMAT). Simulation results show that stress concentration and redistribution occur around the cooling holes during the creep development. It is also shown that the maximum strain and stress are around the cooling holes which are the initial rupture region in the experiments.

Abstract: a Design Concept of Piecewise Variable Wall Thickness of Radome Is Proposed to Simulate the Radome which Has Variable Wall. the Paper Calculates the Far Field of a Medium-Size Radome in the Case of Piecewise Variable Thickness by Three Methods as Follows: Method of Moment (MOM), Multilevel Fast Multipole Method (MLFMM) and Physical Optics& the Method of Moments (PO/MOM) Respectively. after Comparing the Results, we Find that the PO/MOM Method Have the Superiority in Simulation of Radome’s Electromagnetic because it’s More Accuracy and Less Memory Consuming than the other Two Methods. Also it Proves the Feasibility of the Design Concept of Piecewise Variable Thickness for Radome.

Abstract: A reliability-based multidisciplinary design optimization (RBMDO) frame work for Centrifugal compressor was presented. Multidisciplinary feasible method was used to decouple the multidisciplinary analysis and the fourth moment method for reliability analysis was recommended systematically. Based on the approximation, the RBMDO framework was finished. The case study shows that optimization efforts could improve obviously the performance of centrifugal compressor under the requirements of reliability. This framework could make the design reach the best performance with a good reliability. It indicates that the proposed optimization method is available and feasible for the engineering application.

Abstract: Based on the microstructure change and damage characteristics of single crystal, a two-state-variable crystallographic creep damage constitutive model has been developed to investigate crack growth behaviors of single crystal compact tension specimen at 760 for two crack orientations: (001)[100] and (011)[100]. Numerical simulation results show the crack-tip stress fields are dependent on crack crystallographic orientation. Observations performed on the real single crystal specimens reveals that the macroscopic crack growth path appears as zigzag wave. The creep deformation at crack tip takes place in specific slip plane, and the deflection angles of crack initiation direction from the crack plane are 45º or 135 º and 53.7ºor 127.3º in the crack orientations (001)[100] and (011)[100]. A good agreement between experimental observations and numerical results is found.

Abstract: For the single crystal (SC) Ni-based superalloys, it is difficult to avoid orientation variation along airfoil stacking line of the SC turbine blade. At the mean time, the loading of turbine blade is uncertainly during the working. In this work, the creep life of the SC turbine blade is determined by the finite element analysis (FEA) based on the crystal slip theory. The orientation variations are measured based larger numbers commercial turbine blade made of SC superalloys. Furthermore, Monte-Carlo method and the forth moment method are presented to analysis the reliability for creep life of SC turbine blade under random crystal orientations and random loads based on the FEA method. The basic variables sensitivity are comprehensively analyzed by the forth moment method.

Abstract: The stress distribution of adhesively-bonded single lap joints under tensile shear loading is analyzed using 2-dimensional elastic-plastic finite element method (FEM). Special attentions have been put on the influence of void in adhesive on the stress distribution of adhesively-bonded joints. The results show that the stress concentration of the void is less than that of the end part of the joints when adhesive layer’s deformation was in the range of elastic. Moreover, the influence of the void on the stress distribution becomes less when the void moving from the end-part to the middle. The stress concentration becomes larger and the stress distribution of adhesive’s mid-thickness region becomes flatter when adhesive layer has biggish plastic deformation. Finite element results show an agreement with the theoretical results.

Abstract: This paper presents an uncertainty propagation analysis method using the Convex Model Theory (CM) for turbine cooling blade multidisciplinary design. Convex Model is used to describe the design variables’ uncertainty, and it’s propagation equation is derived. Monte-Carlo(MC) method and Convex Model Theory (CM) are all employed to calculate target variable’s variation. Result shows that CM method is more time-saving than MC method. First order second moment method is employed to calculate the reliability of target variable’s variation to evaluate the difference of the results of the two methods. As the actual probability density function of design variables is unknown, so reliability analysis considers different probability density functions. Response surface method is used to construct the approximation of the multidisciplinary analysis. Reliability analysis result shows that CM method keeps the same accuracy with MC method.