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Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Aeronautical Materials is the property of Editorial Board of Journal of Aeronautical Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Foundry Technology (1000-8365) is the property of Foundry Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the oil-gas two-phase flow characteristics in the bearing chamber of an aeroengine and improve the oil return effect of lubricating oil,an embedded improvement scheme was proposed for the ventilation structure of the bearing chamber.A two-phase flow solution model for the bearing chamber based on the Euler-Euler method was established,and the flow characteristics and oil return characteristics of conventional bearing chamber and embedded improvement bearing chamber under different operating conditions were analyzed.The results show that after the embedded improvement of the ventilation structure of the conventional bearing chamber,the lubricating oil is blocked by the embedded ventilation wall.Under the action of air shear force and gravity, the lubricating oil on the right side of the ventilation port moves downstream through the ventilation port,reducing the amount of lubricating oil flowing out of the ventilation port and increasing the amount of lubricating oil flowing out of the return port,thus significantly improving the return oil efficiency .As the embedding depth increases, the lubricating oil flowing out of the vent is further suppressed, the volume fraction of the lubricating oil in the chamber further increases,and the return oil efficiency is further improved.Compared with conventional bearing cavities,when the oil flow rate is 200 L/h and the rotation speed is 15 000 r/min,the embedded improvement scheme has the most significant improvement in oil return efficiency,and the oil return efficiency is increased by 16.72%, 18.80%, and 20.19% respectively for the improved schemes with embedded depths of 8 mm, 10 mm,and 12 mm. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Turbine blades are the most demanding components in aircraft engines, and their performance is related to the safety of the whole engine. Due to the complex service environment and harsh service conditions of blades, various types of damage cannot be prevented in service. Therefore, it is of great engineering and economic significance to study the service damage of blades. In this paper, the directional solidification alloy turbine blade after actual service was selected as the research object. The cross section position of 80% upper height of the blade was intercepted, and the qualitative and quantitative microstructure analysis was carried out by SEM and EDS analysis. The results show that there are two different types of γ' phases in this leaf. One kind of γ' phase has small size and regular shape, the other has large size and irregular shape. The degree of microscopic damage among different parts of the blade is characterized with the help of dimensional distribution characterization of the γ' phase of each part, combined with the analysis of hardness testing of each part of the cross-section.The results show that the service conditions of different parts are different, and the degree of microstructure damage is different. In addition, matrix crack and coating crack in some parts of blade are summarized and analyzed. [ABSTRACT FROM AUTHOR]

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The test study on temperature characteristic of an engine anti-icing sensor is carried out in the icing wind tunnel. The results of temperature characteristic changing with air total temperature，heat air flow， heat temperature as well as the droplet parameters are obtained. The experimental results show that the heat air parameters have great effect on the temperature characteristic of the sensor，and the average measuring deviation of the sensor increases as the heat air temperature and flow increase. Sensor application scenario is affected by the aircraft engine operation. In certain conditions，the average measurement deviation of the sensor fluctuates in a reasonable range. The ice formed on the sensor will affect the air flow into the sensor temperature cavity，and cause the increase of the sensor temperature deviation. This will finally lead to the decrease of the sensor performance and even failure of the sensor if the ice amount is too much. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

During the operation of the aircraft drag parachute, the aircraft engine is often not shut down. The high⁃speed engine nozzle flow will have a certain impact on the flow field of the drag parachute, thereby affecting the performance of the drag parachute. To study the influence of engine nozzle flow on the drag parachute, the fluid⁃structure coupling method is used to simulate the dynamic parachute opening process of the drag parachute under different nozzle velocities. And the effect of different nozzle velocities on the drag characteristics and stability of the drag parachute are analyzed. Research has found that the engine nozzle flow will increase the fluid velocity in front of the drag parachute, which causes the drag parachute’s opening shock peak time to move forward, the opening shock peak value increases, and the average value of the aerodynamic resistance increases. When the nozzle flow velocity is 250 m/s, the average aerodynamic resistance of the drag parachute in the full state is increased by 21%. When the nozzle flow velocity is 350 m/ s, the average aerodynamic resistance of the drag parachute is increased by 51%. When the nozzle flow velocity is 500 m/s, the average aerodynamic resistance of the drag parachute is increased by 79%. At the same time, the engine nozzle flow will make the pressure under the inner side of the parachute higher. The asymmetrical pressure distribution of the inner side makes the drag parachute swing up and down. And the greater the nozzle velocity is, the greater the swing amplitude of the drag parachute will be. The nozzle velocity will make the stability of the drag parachute worse. [ABSTRACT FROM AUTHOR]

The proportional hazard model uses multiple variables to synthesize multiple parameters to predict the remaining useful life of the system. However, because the traditional proportional hazard model is based on the assumption that multiple research samples are independent and identically distributed, that is, the basic failure rate is the same, but for aero engines, there are differences in basic failure rates due to different operating environments and uses. Studies have shown that ignoring differences between samples can lead to serious bias in the estimates. To this end, this study will introduce the concept of frailty that is used to express the non-independence between samples, and establish a more general vulnerability proportional hazard model for aircraft engines, which will be used for the first time to predict the remaining useful life of aircraft engines. The example shows that the average error of the prediction results based on the proportional hazard model with frailty is 4.6%, while the average error of the prediction results based on the traditional proportional hazard model is 6.9%, which verifies the effectiveness of the proportional hazard model with frailty in the prediction of the remaining useful life of aero engine. [ABSTRACT FROM AUTHOR]

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The turbocharging matching is researched for the problem of power reduction of two-stroke aero engines at high-altitudes. An one-dimensional simulation model of a natural aspirated two-stroke aero engine was established and experimentally verified. Based on the verified model, a turbocharger is matched,and a turbocharged engine model is established. The structure optimizing and control strategies of bypass valve in exhaust system are proposed to broaden the working range of turbocharger through the calculation and analysis of turbocharging matching at variable altitudes. A two-stroke turbocharged aero engine with 76% power recovery at 7 000 m altitude was designed,which can meet the demand of an unmanned aerial vehicle’s mission profile. [ABSTRACT FROM AUTHOR]

The cabin area of civil aircraft with multi‑turbofan engines is vulnerable to beat noise during cruise flight. In order to find the method for restraining the beating noise，the beating noise model is established by using the pipe acoustic theory. It is clear that the beating noise mainly comes from the simple tone and harmonics of fan blade passing frequency. Applying the principle of linear superposition of sound wave，the mechanism of beating noise for double‑engine/four‑engine aircraft is analyzed，and the method for restraining beat noise is to make the physical speed of all engines consistent. During studying the beating noise for four‑engine aircraft，the formulas for calculating the interference of simple tone wave with different amplitudes and similar frequencies are derived，which provide a reference for restraining the beating noise of three‑engine aircraft and other multiple‑engine aircraft. Meanwhile，In order to promote the engineering application of this technology，the method of restraining beating noise by thrust management function of Boeing 787 aircraft is studied. The control law of restraining beating noise is designed. The upper and lower limits of beating noise frequency modulation are analyzed，and the corresponding recommended values are given. When aircraft system provides the N1 synchronization correction to engine electronic controller（EEC），it should compare the target speed for engine control. And EEC control engine should use the target speed which has been added with the N1 synchronization correction. [ABSTRACT FROM AUTHOR]

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The internal flow of a lubricant vane pump in aircraft engine is simulated using the computational fluid dynamics software Star-cd to estimate the influences of inlet and outlet pressures on its internal flow. A self-compiled code is called by the subroutines of Star-cd to generate the moving mesh of vane pump, especially to capture the gap shape between vane and stator. Rayleigh cavitation model and Menders SST k-ω) model are used in the simulation. The calculated flow rates are obtained under different inlet and outlet pressures. The simulation results demonstrate that the transient flow rate at the inlet is stable, while the transient flow rate at the outlet fluctuates significantly. The calculated results also demonstrate that the flow rate increases significantly with the increase in inlet pressure. And with the increase in outlet pressure, the back flow is increased and the collapse velocity of cavitation is also increased, resulting in a small reduction in the flow flux. [ABSTRACT FROM AUTHOR]

A new Osculating Curved Cone method is developed for hypersonic vehicle degign, in which the method of streamlines tracing axisymmetric flow fields of multi-stage Shockwaves or isentropic compressing waves is used to create the waverider lower surface and inlet hp inner surface. The shape of the vehicle upper surface is governed by the inward deviation from the FCT as a function of axial location, the determination of the primitive flow variables on the upper surface is accomplished through the application of a first order scheme utilizing the axisymmetric method of characteristics, so as to fullfill an accurate yet rapid computational analysis. 2D and 3D MOC tools that can quickly design and analyze nozzle geometries are developed and the performance of SCRAMJET engine is evaluated by a ID method. A model vehicle about 3 meters long at on-design operation point Mach 6 is presented, and the results of numerical simulations and wind tunnel experiments show that rapid analysis has a moderate accuracy. The SCRAMJET engine works well and the vehicle obtains net positive thrust at design condition. [ABSTRACT FROM AUTHOR]

In the paper, a hierarchical theory based cooperation module with 3 layers, named cooperative sensing-, situation comprehending-, and global replanning-layer, is introduced to address the problem of multiple unmanned air vehicles (MUAVs) dynamic cooperation under uncertain environment. Specifically, a layer cooperative operator (LCO) is proposed for the purpose of target sensing and recognition, and window optimized potential field (WOPF) strategy is adopted for obstacle avoidance and environment adaption consideration, while layer sense engine operator (LSEO) is suggested to enhance the module's ability of global replanning and MUAVs trajectory optimization. Simulation results indicate the promising potential of our proposed module in the area of MUAVs autonomous cooperation under uncertain environment. [ABSTRACT FROM AUTHOR]

A method for designing switching control of a one-spool aircraft engine is proposed. The method can decrease switching frequencies among the models. Firstly, a Lyapunov approach is used to stabilize the nonlinear control system by choosing a suitable set of control parameters, leading to nonlinear model-based acceleration control. Then switching-based acceleration control is obtained for the two operating points. Simulation results show that the performance of the nonlinear model-based acceleration control is better than that of the switching-based control. Meanwhile, the former method uses only one nonlinear model, avoiding the model switching problem that is encountered in the switching-based method. The correctness of the proposed design method is thus validated. [ABSTRACT FROM AUTHOR]

A method of condition monitoring and on-wing life prediction for civil aviation aircraft engine is proposed in this study. The dynamic linear model is used to describe the dynamics of the condition monitoring parameters and the Bayes factors are calculated to detect the abnormal of the parameter sequences. Case study on the simulation data set shows the feasibility of the proposed method for fault detection and a timely warning can be given once a fault occurs. The dynamic linear model can be utilized to describe the process of the engine performance deterioration, and further future evolution trend can be predicted within the Bayesian framework. The advantage of the proposed method is that the dynamic linear model can incorporate sudden changes in the performance introduced by the on-line maintenance, washing and fault. The case study on a real data set shows that the proposed method for performance prognostics can give a more reasonable prediction of the engine on-wing life since it takes the real operating conditions into account. [ABSTRACT FROM AUTHOR]

Thermal barrier coatings (TBC) are crucial materials of high-temperature components in aero-engine. Its quality and performance is therefore significant for nondestructive testing (NDT). This paper systematically reviews the history and research state of NDT techniques in the field of TBC. Moreover, it mainly introduces the development direction of NDT techniques which apply to the inspection of thermal grown oxide (TGO) and residual stress in thermal barrier coating. [ABSTRACT FROM AUTHOR]

A two-dimensional model for a certain engine nacelle is simplified, and a numerical simulation for the flow and heat transfer process inside engine nacelle is carried out to illustrate the conjugated action of ventilation cooling, radiation shelter and thermal insulation on reducing skin temperature of engine nacelle. The skin temperature decreases with the increase of the ventilation air flow, but the individual action is not significant when the ventilation flowmate varies from 0. 1 kg/s to 1. 0 kg/s. Radiative heating of the engine wall to internal skin surface can be reduced effectively by setting radiation shelter, resulting in obvious reduction of skin temperature in the middle section of nacelle. The additional thermal insulation layer on the inside of engine nacelle will increase heat conduction resistance, resulting in skin temperature reduction in overall length, especially significant near trailing edge of nacelle. By using a combination of ventilation cooling, radiation shelter and thermal insulation layer, the skin temperature can be decreased close to ambient temperature. [ABSTRACT FROM AUTHOR]

Rear fuselage mounted engine is applied on ARJ21-700 aerocraft. Under some special conditions, the ice shedding from the surface may do harm to the engine. In order to research the relationship between the ice shape, shedding pose or shedding position and the probability of entering engine, MBNS3D is employed to calculate the flowfield of ARJ21-700 and variable ice shapes, and the trajectories of ice shedding from head and upper wing of craft are calculated by solvering six-degree equations. It is found that this method can calculate large amount of trajectories quickly and precisely. Finally, the rule of ice blocks being pulled into the engine is concluded, to provide surpport to the airworthy certification of ARJ21-700. [ABSTRACT FROM AUTHOR]

To reduce maintenance cost and improve performance after a shop visit, a decision-making method for civil aeroengine workscope under uncertain condition is proposed. Firstly, aeroengine overall performance restoration value for each module's maintenance level is expressed as a trapezoidal fuzzy number, and then a fuzzy chance constrained programming model on module performance restoration value distribution optimization is put forward under uncertain condition. Secondly, the chance constraint of the model is transformed into a clear equivalence class. It is found that this model and the optimization model of module performance restoration value distribution under certain condition have the same structure. Thus, the solving method of the model with certain condition is adopted to achieve the model with uncertainty condition. Finally, the proposed method is validated by a real example. The result shows that the proposed method can solve decision-making problem for aeroengine maintenance workscope under uncertainty condition; the reasonable confidence level for the chance constraint of the model is essential to the decision-making result, and could be determined according to the risk of achieving the repair objectives and maintenance cost. [ABSTRACT FROM AUTHOR]

To help shipborne aircrafts take off with the aid of the power of carrier engine the pulse stepless shafts are used as constant power stepless gearbox instead of the present used decelerator for carrier power. When shipborne aircrafts take off, the shafts transmit power to the drum set, around which the cables tow to accelerate the take off shipborne aircrafts. To improve the performance of pulse stepless shafts, point touches in overrunning clutches are converted into face touches, which can be realized by means of hydrostatic pressure lubricating technology. The take off weight can be increased greatly. Using pulse stepless shafts to replace decelerators can improve the cruise performance as well as the combat capibility and the take off expenses can be reduced. [ABSTRACT FROM AUTHOR]