Papers by Keyword: Impact Angle

Abstract: The paper involves the subject and the chosen results of up to now solving of work package “Development of advanced surface treatment of components used in parts of turbines working under the condition of operational temperatures of steam using the HP/HVOF technology of thermal spraying” of the Competence Centre project “Centre of Research and Experimental Development of Reliable Energy Production”. The subject belongs to the field of material engineering and results of solving contribute to fulfilling the main project aim, which is a long time safeguarding of safe, reliable and financially available both classical thermal and nuclear sources of electric power, which consists in extending service life of existing and building new turbo generator blocks. The erosion wear resistance is one of the areas, which were observed. The impact of hard particles on the surface under variable impact angles was simulated in laboratory conditions using an in-house equipment. The wear resistance of selected HVOF sprayed hardmetal and super-alloy coatings was measured and the wear mechanism was evaluated. A strong influence of impact angle on both material volume loss and wear mechanism was monitored. The superior erosion wear properties of super-alloy coatings were proved, regardless the higher hardness of hardmetal coatings.

Abstract: Erosion-corrosion behavior in downhole tubulars and oilfield ground gathering transferring system is interesting in optimum design. This work is addressed to investigate erosion-corrosion behavior of hydraulic perforating equipment during fracturing. The typical fracturing fluid of 0.2% hydroxypropyl guar gum solution mixed with quartz grain was selected. The relationship between erosion-corrosion rate and flow displacement, the effect of the flow impact angle on erosion-corrosion rate is performed on a jet impingement experimental apparatus. In the experiment situation, the erosion-corrosion rate reaches highest at the impact angle of 45°. The erosion-corrosion rate increased exponentially with the increase of flow displacement. The surface morphology of specimen suffer from erosion-corrosion is analyzed by scanning electron microscopy (SEM) to characterize the erosion-corrosion damage mechanisms.

Abstract: In order to achieve the tactical mission of cooperative attack for multi-missiles, in a predetermined direction at a predetermined time, this paper studies the design of guidance law with impact angle and impact time constraints. Firstly, using the optimal control theory, the optimal guidance law is designed to control the impact angle, based the relative motion between missile and target. Then the state feedback guidance law is designed to control the arrival impact time, with the application of feedback linearization control theory. Finally, reference the design idea of two-stage guidance system, the anti-ship missile use two different guidance laws in the process of attacking the target. During the first stage, the state feedback guidance law is used to accurately control the impact time and coarsely control the impact angle. During the second stage, the optimal guidance law is used to accurately control the impact angle. And the correctness and effectiveness of the design method is verified by simulation.

Abstract: The influences of the impact angle and the corrosive agent acidity on low-chromium and nickel contained cast iron were studied in the behavior of erosion wear. The wear rule was summarized and the mechanics of the erosion wear behavior were analyzed in this thesis. Erosion wear experiments were carried on MCF-30 erosion test machine, and then the structure and surface morphology of the samples were analyzed by Scanning Electron Microscopy (SEM). The results showed that the alloy carbide (Fe, Cr)3C was generated by a kind of reticulate distribution in the matrix after oil quench at 960°C and temper at 250°C. The continuous and homogeneous distribution, just like the skeleton of the material, enhanced the wear resistance. The shape of erosion wear curve was M at different impact angles. The biggest wear rate occurred at a 60-degree impact angle. The erosion wear property was greatly affected by the strong acid, but it can be ignored when pH3.

Abstract: In order to further study the impact crushing mechanism of cement clinker, the impact experiment has been carried out at different impact angles. Impact crushing curves, acoustic emission signal and peak impact force and impact fracture morphology have been systematically studied. It is shown that each impact crushing curve includes an inertia peak and an actual impact peak. AE signal directly reflects the crack initiation and propagation during the process of impact experiment. With the increase of impact angle, the average value of peak impact force decreases. The peak impact force value reaches the minimum at 75 °. The experiment results will offer a successful alternative to the low – energy grinding of cement clinker.

Abstract: Cooling from impinging jet is nearly compulsory in steel industry processing especially in Run Out Table processing and steel tubes production because of the high heat transfer rates provided by the boiling of the subcooled water jet. As far as metallurgical phase transformations, residual stresses and deformations in the workpiece are concerned, the temperature drop during cooling must be perfectly controlled thanks to a fully understanding of the heat transfer mechanisms. In a previous study [1] the effect of surface to jet velocity ratio on heat transfer has been characterized and it has been shown that this parameter has a significant influence on shoulder of flux collapse. In order to understand the effect of more industrial quench process parameters, an innovative experimental quenching device has been designed and built. It allowed us to make heat transfer measurements at the surface of a hot nickel cylinder impinged by a subcooled water jet, according to several angles of impact and three jet directions against gravity. The results clearly highlight an effect of these two parameters on the heat transfer mechanisms at the surface of the tube. These results allow a better understanding of the origins of temperature heterogeneities inside the tube during the quench.

Abstract: The polymethymethacrylate (PMMA) plate was adopted as the test samples. The effects of impact angle, impact velocity, sand size on the erosion wear of the PMMA plates were experimentally investigated. The erosion mechanisms were also analyzed. The results showed that, the erosion volume increased nonlinearly with the increase of impact velocity, the inflection point appeared at around 13 m/s, and then the erosion volume increased rapidly. The erosion volume decreased nonlinearly as the impact angle increased. In our experiments, under the impact angle less than 60°, the smaller sand size could result in higher erosion wear. However, at 90°, the erosion volume by larger sands produced higher erosion. In fact, the erosion mechanism depends on the impact angle, at small impact angles, the main erosion mechanism is micro-cutting, and the erosion mechanism will mainly be impacting fatigue at large impact angles. At the medium impact angles, the erosion mechanism is the combination of the micro-cutting and impacting.

Abstract: Having an insight on the fluid field in AWJ machining is of important significance but the direct observation and measurement can be hardly implemented. Thus a 3D simulation of the fluid field in AWJ has been undertaken using FLUENT 6.3. The pressure and velocity distribution results on the impacted surface under different impact angle conditions are acquired and analyzed. The influence of the impact angle on the characteristics such as the symmetry of the distribution, position of the maximum value and the stagnation effect is highly concerned. In addition, an experiment under the similar conditions of the simulation is conducted and the results are compared with that of the simulation.

Abstract: In the modern warfare, the trajectory of flight vehicle was required to have the ability to be adjusted in specified shape to increasing the penetration force. This paper deals with the guidance law and data fusion system to impact a target in specified direction for precision guided munitions. A three-dimensional guidance law is designed by combining the optimal guidance law and terminal acceleration tuning methodology. A new configuration of Extended Kalman Filter (EKF) is employed to obtain the range and angle information from INS and infrared seeker to improve the survivability of guidance system in the circumstance with strong electromagnetic interference.

Abstract: Erosion wear experiments on Nickel-Chromium cast iron were tested by MCF-30 erosion test machine. The structure and surface morphology of these samples were analyzed by Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM) and XRD. The influences of the impact angle and acidity on erosion wear property were analyzed. The discipline of the erosion wear property was discussed as well. The experimental results indicate that after oil quench at 960°C and temper at 250°C, the alloy carbide (Fe, Cr)₃C which works as the wear resistance skeleton distributes uniformly in the matrix ; the shape of erosion wear curve is “M”. and the biggest wear loss is when the impact angle is 60°; the erosion wear property is affected greatly by the strong acid, but is little even can be ignored when pH≥3. The erosion wear mechanism of Nickel-Chromium cast iron is selective wear.