Foreign Object Damage to Fan Rotor Blades of Aeroengine Part I: Experimental Study of Bird Impact

AbstractThe conditions of experiment for bird impact to blades have been improved. The experiment of bird impact to the fan rotor blades of an aeroengine is carried out. Through analyzing the transient state response of blades impacted by bird and the change of blade profile before and after the impact, the anti-bird impact performance of blades in the first fan rotor is verified. The basis of anti-foreign object damage design for the fan rotor blades of an aeroengine is provided

Foreign Object Damage to Fan Rotor Blades of Aeroengine Part II: Numerical Simulation of Bird Impact

AbstractBird impact is one of the most dangerous threats to flight safety. The consequences of bird impact can be severe and, therefore, the aircraft components have to be certified for a proven level of bird impact resistance before being put into service. The fan rotor blades of aeroengine are the components being easily impacted by birds. It is necessary to ensure that the fan rotor blades should have adequate resistance against the bird impact, to reduce the flying accidents caused by bird impacts. Using the contacting-impacting algorithm, the numerical simulation is carried out to simulate bird impact. A three-blade computational model is set up for the fan rotor blade having shrouds. The transient response curves of the points corresponding to measured points in experiments, displacements and equivalent stresses on the blades are obtained during the simulation. From the comparison of the transient response curves obtained from numerical simulation with that obtained from experiments, it can be found that the variations in measured points and the corresponding points of simulation are basically the same. The deforming process, the maximum displacements and the maximum equivalent stresses on blades are analyzed. The numerical simulation verifies and complements the experiment results

Microstructure and properties of a deformation-processed Cu-Cr-Ag in situ composite by directional solidification

Cu-7Cr-0.07Ag alloys were prepared by casting and directional solidification, from which deformation-processed in situ composites were prepared by thermo-mechanical processing. The microstructure, mechanical properties, and electrical properties were investigated using optical microscopy, scanning electronic microscopy, tensile testing, and a micro-ohmmeter. The second-phase Cr grains of the directional solidification Cu-7Cr-0.07Ag in situ composite were parallel to the drawing direction and were finer, which led to a higher tensile strength and a better combination of properties

Experimental Study on Dynamic Compression Mechanical Properties of Aluminum Honeycomb Structures

In this paper, dynamic compression tests are developed to investigate the dynamic compression mechanical properties of the aluminum honeycomb structures at different strain rates, especially at the high strain rates. The difficulties at the high strain rates exist due to the large deformation, the low wave resistance and the size effect of the honeycomb structures. The Split Hopkinson Pressure Bar (SPHB) test method is carried out and special measures such as the adoption of waveform shaper, the size optimization of the impact bar and the specimen, and employment of the semiconductor strain gauge, etc. are taken to overcome the difficulties. It is discovered that the dynamic compression mechanical properties possess a stress hardening effect at a high strain rate from 1.3 × 103 s−1 to 2.0 × 103 s−1, but then a stress softening effect at a high strain rate of 4.6 × 103 s−1. It is also discovered that the yield strength and the average plateau stress at the strain rate of 2.0 × 103 s−1 is higher than that at the strain rate of 1.3 × 103 s−1. However, the yield strength and the average plateau stress at the strain rate of 4.6 × 103 s−1 is lower than that at the strain rate of 2.0 × 103 s−1 and 1.3 × 103 s−1, but higher than that at a quasi-static state. This indicates that the aluminum honeycomb structure is sensitive to the strain rate. Additionally, the damage mode of the aluminum honeycomb structure is plastic buckling, collapse and folding of the cell wall, which is carried out using dynamic compression tests. The folding length of the cell wall at a higher strain rate is found to be longer than that at a lower strain rate. The test results can also be used as the stress–strain curves of the honeycomb constitutive model at the high strain rates to carry out the numerical simulation of high-speed impact

Research on Repetition Counting Method Based on Complex Action Label String

Smart factories have real-time demands for the statistics of productivity to meet the needs of quick reaction capabilities. To solve this problem, a counting method based on our decomposition strategy of actions was proposed for complex actions. Our method needs to decompose complex actions into several essential actions and define a label string for each complex action according to the sequence of the essential actions. While counting, we firstly employ an online action recognition algorithm to transform video frames into label numbers, which will be stored in a result queue. Then, the label strings are searched for their results in queue. If the search succeeds, a complex action will be considered to have occurred. Meanwhile, the corresponding counter should be updated to accomplish counting. The comparison test results in a video dataset of workers’ repetitive movements in package printing production lines and illustrate that our method has a lower counting errors, MAE (mean absolute error) less than 5% as well as an OBOA (off-by-one accuracy) more than 90%. Moreover, to enhance the adaptability of the action recognition model to deal with the change of action duration, we propose an adaptive parameter module based on the Kalman filter, which improves counting performances to a certain extent. The conclusions are that our method can achieve high counting performance, and the adaptive parameter module can further improve performances

A Dense Mapping Algorithm Based on Spatiotemporal Consistency

Dense mapping is an important part of mobile robot navigation and environmental understanding. Aiming to address the problem that Dense Surfel Mapping relies on the input of a common-view relationship, we propose a local map extraction strategy based on spatiotemporal consistency. The local map is extracted through the inter-frame pose observability and temporal continuity. To reduce the blurring of map fusion caused by the different viewing angles, a normal constraint is added to the map fusion and weight initialization. To achieve continuous and stable time efficiency, we dynamically adjust the parameters of superpixel extraction. The experimental results on the ICL-NUIM and KITTI datasets show that the partial reconstruction accuracy is improved by approximately 27–43%. In addition, the system achieves a greater than 15 Hz real-time performance using only CPU computation, which is improved by approximately 13%

Fundamentals of Petroleum Residue Cracking Gasification for Coproduction of Oil and Syngas

Vacuum residue (VR) was stepwise converted via catalytic cracking for liquid and coke gasification for hydrogen-rich syngas in a fluidized bed reactor. Silica sand and spent equilibrium FCC (E FCC) catalyst were used as the catalysts for VR cracking. The liquid yield was about 89 wt % at 568 degrees C using silica sand as catalyst and the conversion ratio of heavy fractions was only 55%. About 60 wt % VR was converted into gas and coke over the E-FCC catalyst at 480 degrees C, showing that the catalyst had too strong acidity for VR cracking. The E-FCC catalyst was thus modified (aged) with both hydrothermal treatment and impregnation of alkali and alkaline-earth metals (K and Mg) to weaken its acidity and facilitate the liquid oil production. The aged FCC (A-FCC) catalyst exhibited appropriate cracking activity to allow both the expected liquid yield of about 80 wt % and heavy fraction conversion ratio of up to 98 wt %. Steam gasification of the deposited coke on the surface of the A-FCC catalyst resulted in the production of syngas containing CO and H-2 content to be about 45 and 42 vol %, respectively

Fuel

The so-called petroleum residue cracking gasification (RCG) process intends to convert the heavy oil first into cracked liquid by catalytic cracking and then into syngas via catalytic gasification of the cracking-formed coke. A bifunctional catalyst (BFC) was synthesized in this article and tested for the petroleum residue cracking gasification in a laboratory-scale fluidized bed reactor through comparison with the performance over an FCC catalyst. Low liquid yield of vacuum residue (VR) cracking was obtained with fresh BFC and FCC catalysts because of their strong acidity and thus activity. Hydrothermal treatment was thus performed to weaken the acidity of both the catalysts. This resulted in liquid yields of about 80 wt.% at 500 degrees C for cracking the same VR. The spent BFC and FCC catalysts were both in situ regenerated via steam gasification of the formed coke in the same fluidized bed reactor. This generated simultaneously syngas which contained CO and H-2 of up to 80 vol.%, and the realized carbon conversion was over 95% at 800 degrees C for both the catalysts. However, the regeneration time for BFC was greatly shorter than that for the FCC catalyst. This shows the much better activity of BFC for coke gasification in comparison with FCC that has almost no activity for catalyzing coke gasification. In fact, the BFC contained much more active alkaline metal sites than the FCC to ensure its catalytic activity for gasification. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.The so-called petroleum residue cracking gasification (RCG) process intends to convert the heavy oil first into cracked liquid by catalytic cracking and then into syngas via catalytic gasification of the cracking-formed coke. A bifunctional catalyst (BFC) was synthesized in this article and tested for the petroleum residue cracking gasification in a laboratory-scale fluidized bed reactor through comparison with the performance over an FCC catalyst. Low liquid yield of vacuum residue (VR) cracking was obtained with fresh BFC and FCC catalysts because of their strong acidity and thus activity. Hydrothermal treatment was thus performed to weaken the acidity of both the catalysts. This resulted in liquid yields of about 80 wt.% at 500 degrees C for cracking the same VR. The spent BFC and FCC catalysts were both in situ regenerated via steam gasification of the formed coke in the same fluidized bed reactor. This generated simultaneously syngas which contained CO and H-2 of up to 80 vol.%, and the realized carbon conversion was over 95% at 800 degrees C for both the catalysts. However, the regeneration time for BFC was greatly shorter than that for the FCC catalyst. This shows the much better activity of BFC for coke gasification in comparison with FCC that has almost no activity for catalyzing coke gasification. In fact, the BFC contained much more active alkaline metal sites than the FCC to ensure its catalytic activity for gasification. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved