scholarly journals Theoretical dependence of the strength of a plasma coating taking into account the mutual thermal effect of the sprayed particles

Author(s):  
В.П. Бушланов

Перспективным способом восстановления изношенных деталей является газоплазменное напыление, позволяющее получать заданные эксплуатационные свойства поверхности. В статье теоретически вычислена вероятность взаимодействия напыляемых частиц в период их тепловой активности, зависящая от единственного параметра равного произведению числа напыленных частиц и квадрата отношения радиуса диска частицы на подложке к радиусу пятна напыления. Получено аналитическое выражение прочности плазменного покрытия на отрыв от параметров процесса напыления с учетом взаимного теплового влияния напыляемых частиц от единственного безразмерного параметра. Безразмерный параметр равен отношению произведения времени термической активности частиц, массового расхода, коэффициента прилипания, квадрата радиуса диска частицы на подложке к произведению массы частицы и квадрата радиуса пятна напыления. Gas-plasma spraying is a promising method for the restoration of worn-out parts, which makes it possible to obtain the performance properties of the surface. In the article the probability of interaction of the sprayed particles during the period of their thermal activity is theoretically calculated, depending on a single parameter equal to the product of the number of sprayed particles and the square the ratio of the radius of the disk of the particle on the substrate to the radius of the deposition spot. An analytical expression is obtained for the separation strength of a plasma coating from the parameters of the spraying process, taking into account the mutual thermal effect of the sprayed particles from a single dimensionless parameter. The dimensionless parameter is equal to the ratio of the product of the time of thermal activity of particles, mass flow rate, adhesion coefficient, square of the radius of the disk of the particle on the substrate to the product of the mass of the particle and the square of the radius of the spray spot.

2018 ◽  
Vol 22 (1 Part A) ◽  
pp. 247-262 ◽  
Author(s):  
Hong-Bing Ding ◽  
Chao Wang ◽  
Gang Wang

2020 ◽  
Vol 13 (3) ◽  
pp. 206-221
Author(s):  
Vijayan Gopalsamy ◽  
Karunakaran Rajasekaran ◽  
Logesh Kamaraj ◽  
Siva Sivasaravanan ◽  
Metin Kok

Background: Aqueous-alumina nanofluid was prepared using magnetic stirrer and ultrasonication process. Then, the prepared nanofluid was subjected to flow through the unshielded receiver of the parabolic trough solar collector to investigate the performance of the nanofluid and the effects of the dimensionless parameter were determined. Methods: The experimental work has been divided into two sections. First, the nanofluid was prepared and tested for its morphology, dimensions, and sedimentation using X-Ray Diffraction and Raman shift method. Then, the nanofluids of various concentrations from 0 to 4.0% are used as heat transfer fluid in unshielded type collector. Finally, the effect of the dimensionless parameter on the performance was determined. Results: For the whole test period, depending upon the bulk mean temperature, the dimensionless parameters such as Re and Nu varied from 1098 to 4552 & 19.30 to 46.40 for air and 2150 to 7551 & 11.11 to 48.54 for nanofluid. The enhancement of thermal efficiency found for 0% and 4.0% nanoparticle concentrations was 32.84% for the mass flow rate of 0.02 kg/s and 13.26% for the mass flow rate of 0.06 kg/s. Conclusion: Re and Nu of air depend on air velocity and ambient temperature. Re increased with the mass flow rate and decreased with concentration. Heat loss occurred by convection mode of heat transfer. Heat transfer coefficient and global efficiency increased with increased mass flow rate and volume fraction. The thermal efficiency of both 0% and 4.0% concentrations became equal for increased mass flow rate. It has been proven that at high mass flow rates, the time available to absorb the heat energy from the receiver is insufficient.


Author(s):  
V.N. Petrov ◽  
◽  
V.F. Sopin ◽  
L.A. Akhmetzyanova ◽  
Ya.S. Petrova ◽  
...  

Author(s):  
Roberto Bruno Bossio ◽  
Vincenzo Naso ◽  
Marian Cichy ◽  
Boleslaw Pleszewski
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