2002 Vol. 28, No. 1

Display Method:
Effects of Roughness Ribs on Flow Patterns of Simplified Aircraft Model
WANG Jin-jun, XUE Qi-zhi, WANG Hai-wen, LI Yan
2002, 28(1): 1-3.
Abstract:
The dye-injection flow visualization technique has been used to study the flow patterns of a simplified aircraft model, the effects of side roughness ribs and "O" type with side roughness ribs on the flow patterns have been observed in details. The experimental results indicated that the range of the angle of attack influenced by the Reynolds number in the pitching moment curves is related to the angle of attack at which the nose vortex begins to beat the canopy until it mixes in the front of the canopy. In this water tunnel experiments, the results obtained at 20cm/s for the roughness height 0.8mm can be used to explained the scatter of the pitching moment curves obtained in the wind tunnel measurements.
Improved Solvable Condition for H Control Problem via State Feedback
ZENG Jian-ping, CHENG Peng, ZHANG Li-jun
2002, 28(1): 4-7.
Abstract:
Simplified solvable condition for H control problem via state feedback is considered. The solvability of H control problem via state feedback is considered to be equivalent to that of a class of linear matrix inequality (LMI). It can reduce the variable dimension by deleting redundancy matrix variables for the class of LMI, and a dimension-reduced LMI is obtained then. Moreover, the feasible solution set to the former LMI can be reconstructed via that of the latter. On the above basis, an improved solvable condition for H control problem via state feedback is deduced. The H controller set can be constructed by the feasible solution to the simplified solvable condition, and it also has more plentiful free parameters. Finally, two simple examples are given to show the validity of this approach.
Nonisothermal Adsorption Model for Molecular Sieve Oxygen Concentrator(MSOC)
YANG Feng, LIN Gui-ping, ZHAO Jing-quan
2002, 28(1): 8-11.
Abstract:
The operating principle of the OnBoard Oxygen Generating System (OBOGS) and the basic theory of enriching oxygen with Pressure Swing Adsorption (PSA) are briefly introduced. A nonisothermal adsorption model to simulate the dynamic PSA process has been established with consideration of the factors of mass transfer, heat transfer as well as pressure variation in the column. In the model, linear driving force for adsorption rate and mixed Langmuir isothermal theory for calculating equilibrium amount adsorbed are adopted. The adsorption process of adsorption bed is simulated and the result is analyzed.
Design and Implementation of Certain SelfAdapted Telemetry Frame Synchronizer
KUANG Wei, ZHANG Xiao-lin, TAN Shuang
2002, 28(1): 12-16.
Abstract:
This self-adapted telemetry frame synchronizer is designed for certain UAV , which telemetry-data frame-format is altering with different working modes. This frame synchronizer is controlled by software, so its parameters can be adjusted on real time to adapt various frame-formats. After that , EPROM is applied to achieve correlation-detect, and FPGA to form peripheral circuit. Through elaborate design, it can work on 4Mbps. Based on performance analysis, the parameters of the synchronizer are optimized to meet the needs. Recent test-fly approve that it can work steadily and measure all design targets.
Scheme of Secure Telemetry Data Transmitting System Using in Certain UAV System
KUANG Wei, ZHANG Xiao-lin, HU Yi
2002, 28(1): 17-20.
Abstract:
The scheme of secure telemetry data transmitting system using in certain UAV system is discussed here. This encryption not only has strong security, but also can be easy realized, with few error-spreading and no message-spreading. Thinking of the error correction coding technique in this telemetry data transmitting system, the encryption technique and coding technique are tie in one by reasonable way, so both can behave in best performance. This scheme is very suitable for telemetry data format. Recent test-fly approves this scheme work well and reliably.
Modelling and Fuzzy VariableStructure Control of Agile Missile
DONG Chao-yang, SHI Xiao-rong, ZHANG Ming-lian
2002, 28(1): 21-24.
Abstract:
Advanced agile missiles possess maneuverability, agility and accurate guidance performance by adopting thruster vector control or reaction control system thruster. System dynamics and modelling of the advanced agile missiles is investigated, a variable-structure model-following control approach for the agile missile with reaction control system thruster is presented, real-time logic switching control law is used. In order to overcome the chattering problem existing in most variable-structure control systems, simple fuzzy control laws are introduced in the variable-structure control system, which proved to be effective in not only chattering problem subduction bust also the system robustness enhanced. Numerical simulation results are given to illustrate the effectiveness.
Optimized Design of Environmental Control System for Aircraft Avionics Pods
YU Jian-zu, YU Lei
2002, 28(1): 25-29.
Abstract:
The status of development of the technology of environmental control system(ECS) for avionics pods was introduced, a new type re-cool reverse boot-strap ram air circle cooling scheme of ECS for pods was brought forward. The optimum design mathematical models of typical ECS for pods were created, and the optimum method was discussed. Four types of ECS presently used in military aircraft pods were considered. The sine method combined with simplex method was applied to seek optimal technologic scheme and parameters for these systems. Finally the contrasts and analysis of the results of the system scheme and parameter optimization were made. The results showed that the new pod ECS had less fuel penalty and higher Coefficient of Performance(COP).
Fatigue Life Corrective Factor of Wing-Main-Beam under Corrosive Condition
LI Yu-hai, LIU Wen-ting, JIANG Dong-bin, JIANG Jun
2002, 28(1): 30-33.
Abstract:
Accelerated corrosion tests of simulator specimens of the wing main beam of a kind of fighter plane are carried out for different times which correspond to different years of the plan on grounding, before fatigue test are carried out under load spectrum. By analysis of test data, the curve of grounding corrosion influence factor (C) versus grounding years (T) is obtained. On the basis of load spectrum fatigue test of simulator specimens in various mediums that composed sky part environmental spectrum, sky corrosion fatigue influence factor (K) is determined by the percent weighted composite method. Synthesizing C-T curve and K, fatigue life correction factors of the wing-main-beam under corrosion condition are determined, which correspond to various non-corrosion life and flight hours per year. The results are valuable for evaluation fatigue life of wing-main-beam under corrosion condition.
Study and Implementation of Software Reliability Prediction Method
CONG Min, LU Min-yan, BAI Yun-feng
2002, 28(1): 34-38.
Abstract:
Software-reliability evaluation can estimate and predict reliabilities of software . For the purpose of solving the problems in software prediction process, a practical software-reliability prediction method is proposed to give better software reliability predictions. In this method, a model is selected by analyzing and improving models' prediction quality. U plot, Y  plot and logarithm PLR plot are used to analyze models' prediction quality,recalibration method and combination method are used to improve it. A software-reliability analysis tool based on this method is then developed. With this tool one can do predictions using several kinds of raw software reliability models, analyze prediction quality and improve prediction quality of raw models.
Dynamic Characteristics Analysis of Rotor System Whole Transfer Coefficient Method
HONG Jie, HAN Ji-bin, ZHU Zi-gen
2002, 28(1): 39-42.
Abstract:
Whole Transfer Coefficient Method (WTCM), which was investigated and presented on the basis of Transfer Coefficient Method (TCM), is a new method of dynamic characteristics analysis of rotor system. In dynamic characteristics analysis of coupled multi-rotor system, it has many advantages, good enough calculation accuracy for practical use, fewer memories and less computation time. The critical speeds and modes of coupled dual-rotor system are calculated by WTCM. The results show that the computing speed and stability of numerical value are greatly improved compared with other Transfer Matrix Methods (TMM).
MATLAB Simulation Model of Environmental Control System
SONG Jun-xiao, YUAN Xiu
2002, 28(1): 43-46.
Abstract:
MATLAB is applied to the dynamic simulation of the environmental control system (ECS) of military aircraft. Modeling method of cooling and controlling parts is introduced respectively based on MATLAB. A toolbox for the simulation of the environment control system is then developed. An example of the simulation is given to compare with experimented result. It is found that, with the aforementioned toolbox, the environment control system of aircraft can be simulated quite efficiently at an excellent precision.
On Scatter Factors of Fatigue Life Obeying Different Distributions
HE Xiao-fan, LIU Wen-ting
2002, 28(1): 47-49.
Abstract:
The fatigue life of civil aircraft structures obeys two-parameter Weibull distribution,its scatter factor is significantly different from that obeys logarithm-normal distribution .To analyze the difference and relation of these two scatter factors,the scatter factor formulas of fatigue life which obeys two-parameter Weibull distribution are presented for theoretical calculation and fatigue testing and the values of scatter factors for different materials are given. Comparison efforts between scatter factors obeying these two distributions are conducted theoretically and numerically. The result provides the important technological approach in determining the fatigue scatter factor of the civil aircraft structures.
Differential GPS Reference Station Design Based on OEM
DING Sheng-xi, ZHANG Qi-shan
2002, 28(1): 50-53.
Abstract:
The DGPS positioning model is introduced and the RTCM SC-104 message content is described. The design scheme of the DGPS reference station based on cheap GPS-OEM is proposed. This kind of DGPS reference station is composed of GPS-OEM and microprocessor. The general GPS receiver only can receive the RTCM SC-104 differential correction message, so the binary correction message output by GPS-OEM must be encoded into the RTCM SC-104 standard format. The DGPS positioning experiment was made. The experiment result proves that the positioning precise of the DGPS system constructed by this DGPS reference station can reach to 1~5 meters. Therefore, this DGPS system is economical and practicable.
On Manipulability Based Fault Tolerant Measure of Redundant Robot
LI Jian, LI Jian-feng, WU Zhen, ZHANG Qi-xian
2002, 28(1): 54-57.
Abstract:
When a redundant manipulator suffers a joint failure, its dexterity will be significantly affected. A joint failure may result in a singular configuration even if the manipulator operates in a relatively dexterous configuration, as a result, the manipulator can't perform arbitrary end effector motions. Fault-tolerance of redundant manipulator is examined in this work. Considering the condition that one joint is failed, manipulability is explored to evaluate the fault-tolerant property and new measure is proposed. This measure is characterized by little computation and can be implemented online. Finally, simulation result illustrates the validity of the proposed measure.
Research on Wedge Type Torsional Vibrator
CHEN Zhi-tong, ZHANG De-yuan
2002, 28(1): 58-62.
Abstract:
To solve the big bulk, high cost and short life span problem of current vibration tapping and reaming system , and to promote application of the high performance vibration tapping and reaming technology, they proposed a wedge type torsional vibrator, which is of much smaller pressure angle, more compact,and which is symmetry in construction and easy to be fabricated. They obtained its output movement constraint equations, its cam curves' equations and synthesis methodology. They also gave an example to prove the validity of the equations. The vibrator can be widely applied to vibration tapping and reaming process .
Analysis of Stress Intensity Factor of Interfacial Crack in TBC
YANG Xiao-guang, LIU Liu
2002, 28(1): 63-65.
Abstract:
The local collocation technique was used to evaluate the stress intensity factor of the interfacial crack. Combined with finite element method, it is used to compute the stress intensity factor of the interfacial crack between the ceramic coating and bond coating of thermal barrier coating under tensile load and thermal load. The stress intensity factor of the interfacial crack is complex, it includes the magnitude and phase angle, so the method to determine the K factor is different from traditional methods that are used to determine the K factors of homogeneous material. Finally, the results are discussed.
Identifying Human Pilot Model in TwoAxis Control Task
QU Xiang-ju, TAN Wen-qian
2002, 28(1): 66-69.
Abstract:
A simplified methodology is described for identifying human pilot describing function in a two-axis control task. A real time simulation is carried out on simulator, in which pilot tracts the command velocity and pitch angle of aircraft by controlling the stick and throttle respectively. Coherence functions between the two-axis show a weak coupling in this task. This suggests it is possible to treat the two-axis control system as two single axes respectively for the pilot model identification for the longitudinal control task. The feasibility and rationality of simplified methodology is demonstrated in both theory and simulation experiment for the control task.
Fast Route Planning Algorithm for Vehicle Location and Navigation Systems
PENG Fei, LIU Zhong-kan, ZHANG Qi-shan
2002, 28(1): 70-73.
Abstract:
Route planning is widely recognized to be a critical issue in the field of vehicle navigation. By examining fast route planning algorithms used in vehicle location and navigation systems,a high-efficient implementation method of shortest-path searching algorithm was proposed in this paper,which is realized by utilizing radix heap structure,heuristic searching algorithm,and hierarchical searching method based on multiple layer map structure synthetically. Simulation results showed that,by introducing this algorithm,the time consumption of route planning can be reduced significantly.
Approximate Function Based Mathematical Modeling in Material Corrosion
DENG Yang-chen, LI Zheng-neng, ZHANG Yi-ning, CHENG Ji-wei
2002, 28(1): 74-77.
Abstract:
The approximate function was led to mathematical modeling in material corrosion. By the characteristic of corrosion data, the divisional mathematical modeling concept was proposed. And it was compared with three models, which were gray model, dynamic data & bi-directional difference model and power function model respectively. The results told us that approximate function model owned not only strong adaptation but applied foreground in engineering as well, besides the highest accuracy over the other three models. From the models posed in this article, we suggested that 'critical point in material corrosion' should exist to some extent.
Simulation of Direct Torque Control System of Induction Motors Using MATLAB
GUO Hong, WANG Guang
2002, 28(1): 78-81.
Abstract:
A simulation method of direct torque control system of induction motor is presented, based on MATLAB. After discussing the configuration and working style of the direct torque control system, a simulation method, which is able to analyze the characteristic of the whole system, is proposed, based on the simulation environment and various blocksets provided by MATLAB. This includes realizing the simulation of the power system using the Power System Blockset, realizing various complex control methods using user-defined S-FUNCTION, and building the model of the direct torque control system in the SIMULINK environment using blocks provided by SIMULINK. An example of simulation is given at the end of this paper, which proves the validity, feasibility and facility of the proposed method.
Dynamic Design of Structures Based on Kind of Inverse Generalized Eigenvalue Problem for Matrices
LI Shu, SUN Zhong-kai, ZHANG Fang, XIANG Jin-wu
2002, 28(1): 82-85.
Abstract:
The stiffness matrix and mass matrix are considered as nonlinear functions of certain parameters such as the areas of cross section of the members. In this paper, a method of structural design of dynamic model is presented and the solving criterion is also given. A first, the problem is treated as a kind of inverse generalized eigenvalue problem for matrices dependent on parameters. Then, according to the characteristic of the inverse generalized eigenvalue problem, the calculation for the global matrices can be transformed into calculation for the specified local matrices. The derivatives of eigenvalues and eigenvectors are solved by a mathematical algorithm. Computing efficiency is improved greatly. The numerical example shows the benefit of the presented methodology.
Independent Initial Alignment of Marine Strapdown Inertial Navigation System in Moorage
ZHOU Li, CUI Zhong
2002, 28(1): 86-89.
Abstract:
A method of independent initial alignment of a marine strapdown inertial navigation system in moorage is studied to arm at the problems which are brought by a base swinging with large angles and centripetal-acceleration disturbance on the base. Parameter identification is used to pick-up the several coefficients in attitude error expressions in order to identify gyro bias and attitude error. Moreover, an idea that compensates in real time acceleration disturbance on a swing base is addressed. Finally, simulation calculations are given to show the validity of the method.
High Speed and Accurate "E-T" Translation Method for Transient Aerodynamic Heating Control System
WU Da, HE Xiao, GAO Zhen
2002, 28(1): 90-93.
Abstract:
To simulate the transient aerodynamic heating condition of high speed flight vehicle, the high speed and accurate computer transient control system must be used to realize the high speed nonlinear dynamic controlling in the heating process of aerodynamic simulation experiment. To reach this aim, a very important problem of high speed and accurate E-T translation of sensor must be solved. A high speed and accurate E-T translation method of sensor for transient aerodynamic heating control system of high speed flight vehicle is proposed. This method possesses many advantages, such as, easy to calculation, with high translating speed and high accurate calibration. Using this method, the transient nonlinear dynamic controlling in the aerodynamic heating process of high speed flight vehicle and under high speed variable temperature field has been realized.
Iterative Method for Hypersonic Non Equilibrium Flows
WANG Hao, WU Song-ping, LU Ye
2002, 28(1): 94-97.
Abstract:
An iterative method based on the implicit TVD schemes of Harten-Yee's type is presented for the full Navier-Stokes equations with chemical source terms. Only the inviscid part of the implicit scheme is updated in every iteration, it makes the iterative algorithm convenient and economical.Numerical tests upon two-dimensional hypersonic non-equilibrium flows with five neutral air species have been taken with the present iterative algorithm. the results are compared with the conventional non-iterative ones. It is shown that the iterative algorithm accelerates the efficiency of computations. Moreover, the algorithm becomes more efficient with the increase of incoming Mach number.
Investigation on Distribution and Variable Rule for Corrosion Depth of Aluminum Alloy Specimen
LI Yu-hai, HE Xiao-fan, CHEN Qun-zhi, LIU Wen-ting
2002, 28(1): 98-101.
Abstract:
Based on the experiment for LY12CZ aluminum alloy stimulator specimen under the typical service atmosphere and accelerated simulator environment in laboratory,which is usually used in making aircraft skin structures,the viewpoint of corrosion damage can be described by the corrosion depth is clarified and the corrosion depth is measured.The distribution function of the corrosion depth is given,the dispersity of the corrosion depth and relationship between the corrosion depth and the corrosion time are studied.And the corrosion equivalent relationship under these two environments is determined by contrasting the corrosion depth.
Equivalent Kt Method for Evaluating Fatigue Properties of Titanium Alloy Welding Specimens
WANG Xiang-ming, LIU Wen-ting, WANG Zhong-bo
2002, 28(1): 102-104.
Abstract:
With regard to the Titanium alloy welding structures generally used in advanced aircraft structures,an equivalent theoretical stress concentration coefficient Kt (Kte) was introduced to describe the fatigue property of welding specimen. On the basis of the fatigue properties of Titanium alloy specimens,a technological approach used to determine Kte is established through fatigue testing for the Titanium alloy welding specimen under a spectrum load. The detailed process determining Kte and some useful results are given by taking the TC4 titanium alloy oxy-arc welding specimen for example.
Structural Function Failure Probability Control Method for Service Life Estimation
LIU Xiao-dong, LIU Wen-ting
2002, 28(1): 105-108.
Abstract:
Notions of probability of structural function failure, probability of function failure for one aircraft and probability of function failure for a fleet are presented. Based on the binomial distribution, a calculating model of structural function failure probability for a durability critical component, one aircraft and a fleet is established. It accounts for structural maintenance procedure after a certain service time. An analytical method capable of determining the repair maintenance time and estimating the service life for aircraft structures is developed based on the function failure probability control. A practical aircraft structural service life estimation, as an example, to demonstrate the application of the methodology is given.
Accelerated Corrosion Environmental Spectrums for Testing Surface Coatings of Critical Areas of Flight Aircraft Structures
LIU Wen, LI Yu, CHEN Qun, HE Xiao
2002, 28(1): 109-112.
Abstract:
An accelerated corrosion environmental spectrum was introduced to test the surface coatings of the critical areas of flight aircraft structures. The spectrum is composed of hot-humid environment、ultraviolet radiation、thermal impingement、low temperature fatigue and salt spray. One single cycle of the spectrum was supposed to be equal to one-year experience in ground environment. In combination with the actual environment of marine and hot-humid area in China, concrete conditions for hot-humid and thermal impingement tests were developed. The proportions of neutral and acidic salt sprays, the ultraviolet radiation time and the method of determining low temperature fatigue stress levels were established. The programming of the accelerated environmental spectrum was conducted by combining the corrosion critical areas of  flight aircraft. The equivalent relations that single cycle represents one year in marine and hot-humid areas were verified by comparing the corrosion degrees between the accelerated corrosion environmental spectrum and ground environmental spectrum.
Research on Life Reliability of Fatigue Crack Propagation
LUO Yi, HUANG Pei-yan, LIU Wen-ting
2002, 28(1): 113-115.
Abstract:
By analyzing stochastic of effects on the fatigue crack propagation life, a few models on life reliability of fatigue crack propagation in common use were compared. On the base, a kind of reliability model, so called the reliability model of fatigue crack propagation life corresponding to fracture toughness, was proposed in this paper. The model is based on the distributions of fatigue crack propagation life & fracture toughness, which were generally accepted as Weibull distribution or logarithmic normal distribution. The paradox about the distribution of crack size was avoided, especially for three dimensional cracks, two-directional crack sizes were included in the maximum stress strength factor in front of the crack. It was suitable to the probabilistic damage tolerance evaluation of structures including all kinds of cracks or faults.
Prediction of Surface Fatigue Crack Growth Lives of Structures under Bending Loads at Elevated Temperature
HUANG Pei-yan, LUO Yi, FEI Bin-jun
2002, 28(1): 116-118.
Abstract:
Based on an empirical J-integral equation proposed earlier, surface fatigue crack growth rates along crack length and depth directions including the J-integral were developed. Using these expressions, the crack growth lives of a SUS304 steel at 550℃ under bending loads are predicted. The fatigue crack growth experiment was carried out in the same condition. The results showed that the predicted curves of crack length and crack depth vs number of cycles agree well with the experimental data. It proved that the method described were available.
Fuel Measurement with Attitude Error Correction by Using CAD Technique
YUAN Mei, WU Hao, ZHANG Jian
2002, 28(1): 119-121.
Abstract:
In order to measure aircraft fuel in any attitude, a real-time fuel measuring method based on CAD technique is presented. First, adopting 3D solid modeling technique, the model of fuel tank of some aircraft is established. The measurement principle with attitude error correction and the structure of the practical test system are then introduced clearly. Using the output data of fuel sensor and information of aircraft attitude, the real-time measurement and attitudeerror correction of aircraft fuel have been done. The experiment results illustrate that this method is very useful because of fast and accurate calculation.
Development of Scanning Frame System for Compact Antenna Test Range Measurements
HU Chun-hua, FAN Rui, CHEN Wu-yi
2002, 28(1): 122-124.
Abstract:
Compact antenna test range (CATR) is a system which simulate the far-field electromagnetic environment in a smaller microwave dark room to measure and research diversiform antennas. Its ultimate performance criterion must be gauged with scanning frame. Based on the principal of compact antenna test range scanning measurements to meet the requirements of planeness, straightness, positioning accuracy and automation, a scanning frame system for compact antenna test range measurements was developed. With its high precision straight line slide guide and planeness minute adjustment, the system can supply all the requirements associated with compact antenna test range measurements.