Sand Erosion Performance of Gradient Ceramic Nozzles by Abrasive Air-Jets

2006 ◽  
Author(s):  
Jianxin Deng
Keyword(s):  
Wear Resistance ◽  
Abrasive Particle ◽  
Particle Impact ◽  
Erosion Wear ◽  
Apparent Increase ◽  
Air Jets ◽  
Air Jet ◽  
Sand Erosion ◽  
The Common ◽  
Compressive Residual Stresses

A SiC/(W,Ti)C ceramic nozzle with gradient structures was produced by hot pressing. The purpose is to reduce the tensile stress at the entry region of the nozzle in abrasive air-jet. The sand erosion performance of this kind gradient ceramic nozzle caused by abrasive particle impact was investigated by abrasive air-jets in comparison with the common one. Results showed that the gradient ceramic nozzles exhibited an apparent increase in erosion wear resistance over the common ceramic nozzles. The mechanism responsible was explained as the formation of compressive residual stresses in nozzle entry region in fabricating process of the gradient ceramic nozzles, which may partially counteract the tensile stresses resulting from external loadings. It is indicated that gradient structures in ceramic nozzles is an effective way to improve the erosion wear resistance of common ceramic nozzles.

Erosion Wear Resistance of CWS Laminated Ceramic Nozzles

2012 ◽  
Vol 538-541 ◽  
pp. 1915-1919
Author(s):  
Jian Xin Deng ◽  
Yang Yang Chen ◽  
You Qiang Xing
Keyword(s):  
Finite Element Method ◽  
Wear Resistance ◽  
Thermal Expansion ◽  
Wear Behavior ◽  
Erosion Wear ◽  
The Finite Element Method ◽  
Apparent Increase ◽  
Coal Water Slurry ◽  
Laminated Structures ◽  
Large Tensile Stress

In coal-water-slurry (CWS) boilers, the nozzle is eroded continuously by the abrasive action of the CWS, and there are high temperature and temperature gradient inside nozzle, which may cause large tensile stress and lead to an increased erosion wear of the nozzle. In this paper, Al2O3/(W,Ti)C+Al2O3/TiC laminated ceramics were developed to be used as nozzles in CWS boilers. The purpose is to reduce the tensile stresses at the nozzle during the CWS burning process. The value of the residual stresses, which arise from a mismatch between the coefficients of thermal expansion of the constituent phases and neighbouring layers, was calculated by means of the finite element method. The erosion wear behavior of the laminated nozzles was investigated and compared with an unstressed reference nozzle. Results showed that the laminated ceramic nozzles exhibited an apparent increase in erosion wear resistance over the unstressed reference one. It is suggested that laminated structures in ceramic nozzles is an effective way to improve their erosion wear resistance in industrial CWS boilers.

Study on Erosion Wear Mechanism of SiC/(W,Ti)C Gradient Ceramic Nozzle Material

2008 ◽  
Vol 375-376 ◽  
pp. 440-444
Author(s):  
Li Li Liu ◽  
Jian Xin Deng
Keyword(s):  
Wear Resistance ◽  
Gradient Material ◽  
Gradient Structure ◽  
Erosion Wear ◽  
Indentation Fracture ◽  
Sand Blasting ◽  
Functionally Gradient ◽  
Test Conditions ◽  
Indentation Fracture Toughness ◽  
The Common

Idea of functionally gradient material (FGM) theory was used to the design of ceramic nozzle. The purpose was to increase the erosion wear resistance at the entrance of the nozzle in dry sand blasting processes. The SiC/(W,Ti)C gradient ceramic nozzles fabricated by conventional hot pressing. The erosion behavior of the SiC/(W,Ti)C gradient ceramic nozzles were investigated in comparison with the common homologous ceramic nozzles. The experimental results have shown that the ceramic nozzles with a gradient structure have superior erosion wear resistance to that of the common homologous ceramic nozzles under the same test conditions. It was shown that the mechanical properties of the gradient ceramic nozzle materials were greatly improved in comparison with that of the common homologous nozzles. The surface Vickers hardness and indentation fracture toughness of gradient ceramic nozzle were greatly improved compared with that of the common homologous nozzles. Therefore, it is indicated that gradient structures in ceramic nozzles is an effective way to improve the erosion wear resistance of the common homologous nozzles.

Fabrication and Performance of Symmetrical Gradient Ceramic Nozzles

2012 ◽  
Vol 472-475 ◽  
pp. 1063-1068
Author(s):  
Jian Xin Deng ◽  
Yang Yang Chen ◽  
You Qiang Xing
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
Hot Pressing ◽  
Erosion Resistance ◽  
Gradient Structure ◽  
Erosion Wear ◽  
Entry And Exit ◽  
Air Jet ◽  
And Performance ◽  
Compressive Residual Stresses

A model for the design of symmetrical gradient ceramic nozzles is presented. The purpose is to form compressive residual stresses at the entry and exit of the ceramic nozzle, and to reduce the erosion wear at these areas during abrasive air-jet machining. A SiC/(W,Ti)C ceramic nozzle with symmetrical gradient structure at its entry and exit was produced by hot pressing. The residual stresses inside this layered nozzle in the fabricating process were calculated by means of the FEM. The mechanical properties at individual layers were measured, the microstructure was examined. The erosion wear of this symmetrical gradient ceramic nozzle was investigated and compared with an unstressed reference nozzle. The production of symmetrical gradient structures with compressive residual stresses within the entry and exit of the nozzle has been proved to be a suitable way to obtain ceramic nozzles with superior erosion resistance.

Twin Pulsating Jets Impingement Heat Transfer for Fuel Preheating in Automotives

2014 ◽  
Vol 663 ◽  
pp. 322-328 ◽  
Author(s):  
Ali Ahmed Gitan ◽  
Rozli Zulkifli ◽  
Kamaruzaman Sopian ◽  
Shahrir Abdullah
Keyword(s):  
Heat Transfer ◽  
Ignition Process ◽  
Pulsation Frequency ◽  
Ir Camera ◽  
Copper Target ◽  
Air Jets ◽  
Air Jet ◽  
Impingement Heat Transfer ◽  
Pulsating Jet ◽  
Pulsating Jets

The problem of environmental pollution and depletion of fossil fuel can be reduced in automotives by using an alternative bio-fuel and improve the ignition process in engine. Both solutions need to use the fuel preheating technique. This work presents the idea of fuel preheating by using exhaust impingement on the fuel tank. Heat transfer between twin pulsating hot air jets and flat copper target was investigated as an application for preheating of automotive fuel to improve ignition process in the engine. The nozzle of 20 mm was used to produce air jet of Reynolds number, Re ≃ 5500 and a temperature of 54°C. The impinged target was imposed to still air surrounding at temperature of 24°C. Pulsating frequencies of 10-50 Hz were applied on air jets by using twin pulsating jet mechanism. The effect of pulsation frequency on heat transfer was measured using IR camera and heat flux-temperature micro foil sensor. The results obtained by both of these methods showed well agreement. Also, the results revealed significant influence of flow rate difference between steady and pulsating jet cases. In addition, the highest Nusselt number, Nu ≃ 7.2, was obtained at pulsation frequency of 20 Hz.

Fluid mechanical aspects of open- and closed-toe flue organ pipe voicing

2011 ◽  
Vol 2 (2) ◽  
pp. 284-295
Author(s):  
D. Steenbrugge
Keyword(s):  
Pressure Measurements ◽  
Jet Instability ◽  
Active Involvement ◽  
Air Jets ◽  
Air Jet ◽  
Hole Area ◽  
Power Regulation ◽  
Organ Pipes ◽  
Organ Pipe ◽  
Jet Characteristics

Open- and closed-toe voicing of flue organ pipes constitute two opposite extremes of possible ways todetermine the air-jet flow rate through the flue. The latter method offers more voicing control parametersand thus more flexibility, at the expense of a necessary pressure loss at the toe hole. Another differencebetween both cases arises from different air-jet characteristics, such as velocity profile, Re number, flowmomentum or aspect ratio, the latter influencing jet instability. Furthermore, for closed-toe voicing, the flowfield in the pipe foot is modified by an axisymmetric air jet created through the highly constricted toe hole.Velocity measurements on air jets, pressure measurements in the pipe foot are presented, compared anddiscussed for both voicing methods. The ratio of flue to toe hole area is shown to be the sole pipeparameter to entirely determine the jet velocity and can be useful to quantitatively characterize flue and toehole voicing. Open-toe voicing turns out to be the more delicate and low-pressure only method becauseany modification of the flue has consequences on all aspects of the pipe operation, whereas the closed-toemethod, in connection with higher pressures and with active involvement of cut-up adjustment, allows someseparation between sound timbre and power regulation.

scholarly journals Experimental testing of exterior wall mounted mechanical ventilation exhaust air outlet devices

2021 ◽  
Vol 246 ◽  
pp. 02001
Author(s):  
Ülar Palmiste ◽  
Tauno Meier ◽  
Jarek Kurnitski ◽  
Hendrik Voll
Keyword(s):  
Mechanical Ventilation ◽  
Experimental Testing ◽  
Airflow Rate ◽  
Tracer Gas ◽  
Qualitative Comparison ◽  
Smoke Visualization ◽  
Air Jets ◽  
Air Jet ◽  
Building Wall ◽  
Face Velocity

The purpose of the study was to experimentally test the performance of four types of wall-mounted mechanical ventilation exhaust air outlet devices. A full-scale mock-up of a segment of an external wall with an exhaust air outlet was constructed. The tested exhaust air devices include a gravity louver, fixed-blade louver, louver plate, and exhaust nozzle. The performance assessment included two types of experiments over the exhaust airflow rate range of 25–94 l/s at isothermal conditions with no influencing wind: (i) the particle tracer method with smoke to visualize the exhaust air jets from the outlets, and (ii) the tracer gas method to measure the dilution of CO2 concentration in the exhaust air jet. Furthermore, the aerodynamic performance was comparatively evaluated in terms of pressure drop and exhaust air face velocity at the outlet. The qualitative comparison of airflow patterns by smoke visualization showed notable differences between the tested device types. Concentration decrease evaluation indicated that the exhaust air pollutants are more efficiently transported away from the building wall by exhaust outlets that discharge at 0–45 degrees downwards from the horizontal plane. Discharge angles 60–90 degrees downwards produced a wall-attached jet and the pollutant tracer concentration remained relatively high in the vicinity of the wall.

Taguchi approach to erosion wear optimization of WC-10Co-4Cr sprayed austenitic steel subjected to equisized slurry

2018 ◽  
Vol 70 (9) ◽  
pp. 1774-1782 ◽  
Author(s):  
Gurmeet Singh ◽  
Satish Kumar ◽  
Satbir S. Sehgal
Keyword(s):  
Particle Size ◽  
Stainless Steel ◽  
Wear Resistance ◽  
Process Parameters ◽  
Rotational Speed ◽  
Solid Concentration ◽  
Erosion Wear ◽  
Pump Impeller ◽  
Content Type ◽  
Erosion Test

Purpose This paper aims to optimize the erosion wear analysis of slurry impeller material. Stainless steel (SS-410) was used as the pump impeller material. This erosion test was established to influence the rotational speed, solid concentration, time period and particle size. Fly ash was used as the erodent material. Design/methodology/approach The erosion wear experiments were performed at different particle size, rotational speed, time duration and solid concentration (by weight). These tests were performed at four different speeds of 750, 1,000, 1,250 and 1,500 rpm, and the time durations of these experiments are 75, 120,165 and 210 min. For protective coating, high-velocity oxygen-fuel spray process was used for depositing WC-10Co-4Cr coating on stainless steel. To investigate the influence of controlled process parameters on slurry erosion wear of pump impeller material, Taguchi method was used. Findings Results show that significant improvement in erosion wear resistance has been observed by using WC-10Co-4Cr coating. The process parameters affecting the erosion wear loss were in following order: time > rpm > concentration > particle size. The means of signal-to-noise ratio of stainless steel SS410 with and without coating vary from 93.56 to 54.02 and from 86.02 to 48.18, respectively. Originality/value For the erosion wear rate of both uncoated and coated stainless steel, the most powerful influencing factor was identified as time. The erosion test reveals that the coating exhibits ductile erosion mechanism and shows better erosion wear resistance (approximately two times) compared to uncoated stainless steel.

scholarly journals Effect of Silicon Addition on High-Temperature Solid Particle Erosion-Wear Behaviour of Mullite-SiC Composite Refractories Prepared by Nitriding Reactive

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Xiaochao Li ◽  
Shusen Chen ◽  
Zhaohui Huang ◽  
Minghao Fang ◽  
Yan’gai Liu ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Solid Particle ◽  
Elevated Temperatures ◽  
Silicon Powder ◽  
Wear Behaviour ◽  
Solid Particle Erosion ◽  
Erosion Wear ◽  
Particle Erosion ◽  
Powder Addition ◽  
The Impact

Solid particle erosion-wear experiments on as-prepared mullite-SiC composite refractories by nitriding reactive sintering were performed at elevated temperatures, using sharp black SiC abrasive particles at an impact speed of 50 m/s and the impact angle of 90° in the air atmosphere. The effects of silicon powder addition and erosion temperature on the erosion-wear resistance of mullite-SiC composite refractories were studied. The test results reveal that Si powders caused nitriding reaction to formβ-sialon whiskers in the matrix of mullite-SiC composite refractories. The erosion-wear resistance of mullite-SiC composite refractories was improved with the increase of silicon powder addition and erosion temperature, and the minimum volume erosion rate was under the condition of 12% silicon added and a temperature of 1400°C. The major erosion-wear mechanisms of mullite-SiC composite refractories were brittle erosion at the erosion temperature from room temperature to 1000°C and then plastic deformation from 1200°C to 1400°C.

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