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Influences of Hole Shape on Film Cooling Characteristics with CO_2 Injection

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Chinese Journal of Aeronautics 2008年第5期21卷 393-401页

作者：李广超朱惠人樊慧明西北工业大学动量与能源学院西安710072

This article presents the data about heat transfer coefficient ratios, film cooling effectiveness and heat loads for the injection through cylindrical holes, 3-in-1 holes and fanned holes in order to characterize the film cooling performance downstream of a row of holes with 45° inclination and 3 hole spacing apart. The trip wire is placed upstream at a distance of 10 times diameter of the cooling hole from the hole center to keep mainstream fully turbulent. Both inlet and outlet of 3-in-1 holes have a 15° lateral expansion. The outlet of fanned holes has a lateral expansion. CO2 is applied for secondary injection to obtain a density ratio of 1.5. Momentum flux ratio varies from 1 to 4. The results indicate that the increased momentum flux ratio significantly increases heat transfer coefficient and slightly improve film cooling effectiveness for the injection through cylindrical holes. A weak dependence of heat transfer coefficient and film cooling effectiveness, respectively, on momentum flux ratio has been identified for the injection through 3-in-1 holes. The in- crease of the momentum flux ratio decreases heat transfer coefficient and significantly increases film cooling effectiveness for the injection through fanned holes. In terms of the film cooling performance, the fanned holes are the best while the cylindrical holes are the worst among the three hole shapes under study.

关键词： aerospace propulsion system gas turbine film cooling effectiveness heat transfer coefficient

Aerodynamic Design and Analysis of a Low-reaction Axial Compressor Stage

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Chinese Journal of Aeronautics 2008年第1期21卷 1-7页

作者：羌晓青王松涛冯国泰王仲奇哈尔滨工业大学能源科学与工程学院

There is introduced a new low-reaction, highly-loaded axial compressor design concept which is coupled with boundary layer suction method. The characteristic features of the concept are made clear through its comparison with the MIT boundary layer suction compressor. Also are pointed out the potential applications of this concept as well as its key technological problems. Based on this concept, a single-stage, low-reaction and low-speed axial compressor is constructed in association with analysis and computation of boundary layer suction on vanes with the aid of a three-dimensional numerical approach. The results attest to the effectiveness of this way to control separation in blade cascades by the boundary layer suction and the feasibility of this proposed design concept.

关键词： aerospace propulsion system low-reaction axial compressor boundary layer suction energy loss

Linear-in-Parameter Models Based on Parsimonious Genetic Programming Algorithm and Its Application to Aero-Engine Start Modeling

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Chinese Journal of Aeronautics 2006年第4期19卷 295-303页

作者：李应红尉询楷 Department of Aircraft and Power Engineering School of Engineering Air Force Engineering University

A novel Parsimonious Genetic Programming （PGP） algorithm together with a novel aero-engine optimum data-driven dynamic start process model based on PGP is proposed. In application of this method, first, the traditional Genetic Programming（GP） is used to generate the nonlinear input-output models that are represented in a binary tree structure; then, the Orthogonal Least Squares algorithm （OLS） is used to estimate the contribution of the branches of the tree （refer to basic function term that cannot be decomposed anymore according to special rule） to the accuracy of the model, which contributes to eliminate complex redundant subtrees and enhance GP＇s convergence speed; and finally, a simple, reliable and exact linear-in-parameter nonlinear model via GP evolution is obtained. The real aero-engine start process test data simulation and the comparisons with Support Vector Machines （SVM） validate that the proposed method can generate more applicable, interpretable models and achieve comparable, even superior results to SVM.

关键词： aerospace propulsion system linear-in-parameter nonlinear model Parsimonious Genetic Programming (PGP) aero-engine dynamic start model

The Application of Support Vector Machines to Gas Turbine Performance Diagnosis

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Chinese Journal of Aeronautics 2005年第1期18卷 15-19页

作者：郝英孙健国杨国庆白杰 College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Aeronautical Mechanics and Avionics Engineering College Civil Aviation University of ChinaTianjin 300300China College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Civil Aviation Administration of China Beijing 100000China

SVMs（support vector machines） is a new artificial intelligence methodology derived from Vapnik＇s statistical learning theory, which has better generalization than artificial neural network. A Csupport vector classifiers Based Fault Diagnostic Model （CBFDM） which gives the 3 most possible fault causes is constructed in this paper. Five fold cross validation is chosen as the method of model selection for CBFDM. The simulated data are generated from PW4000-94 engine influence coefficient matrix at cruise, and the results show that the diagnostic accuracy of CBFDM is over 93 % even when the standard deviation of noise is 3 times larger than the normal. This model can also be used for other diagnostic problems.

关键词： aerospace propulsion system performance diagnosis support vector machines model selection

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航空发动机高速滚珠轴承振动特性研究

风机技术 2023年第3期65卷 59-65页

作者：唐云冰章璟璇施玲玲谢小虎 Changzhou E&E Turbo-Power Co. Ltd.

Ball bearing is widely used as rotor *** is a non-negligible source of vibration in *** vibration characteristics of the highspeed ball bearing are studied in this *** kinematics theory is applied to discuss the basic characteristics of ball *** vibration factors caused by ball bearings are analyzed,and then the vibration model of ball bearings is set *** effect of the unbalance,the ball passage vibration,the radial clearance and the surface waviness are *** is found that the ball passage vibration is excited by the contact force between the balls and the *** the numbers of ball can reduce the vibration *** surface waviness which is caused due to the geometric imperfection of ball bearings is considered as one of the important vibration sources of bearing systems.

关键词： aerospace propulsion system Ball Bearing Ball PassageVibration SurfaceWaviness