Homender Kumar
@pec.ac.in
ASSISTANT PROFESSOR
Punjab Engineering College (Deemed to be University), Chandigarh
EDUCATION
Ph.D, M.Tech and B.Tech
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
H. S. Sunil Kumar, K. R. Jagadeesh, R. B. Anand, T. Rangaswamy, Srikanth Salyan, Jenoris Muthiya Solomon, Joshuva Arockia Dhanraj, and Joshua Stephen Chellakumar Isaac Joshua Ramesh Lalvani
Hindawi Limited
The present work focuses on the effect of flutter in prebend 100 m horizontal axis wind turbine blade (HAWT) within the stability limits. The study was carried out with an advanced beam model for idyllic structure in a DU-97-W-300 cross-sectional area. A Galerkin type of approach has been applied to derive the equations, and the analysis was performed using a standard FEA code which involves the PK method and double lattice method for calculating flutter solution and aerodynamic loads respectively. The results reveal the significance of inducing prebending to improve the stability of the blade structures, and hence, the flutter velocity has moved from 11 m/s to 23 m/s. Furthermore, the output highlights the effect of prebending on the structural stability and also the flutter limit was found to be lengthened.
Homender Kumar and A. P. Harsha
ASME International
Abstract This current study emphasized the tribological performances of COOH-functionalized multiwalled carbon nanotubes (MWCNTs) dispersed in two different grades of polyalphaolefins (i.e., PAO 4 and PAO 6). The friction and wear properties have been estimated using SRV 5 tribometer with “ball-on-disc” configuration. Prior to tribo testing, MWCNTs were characterized by X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HR-TEM), and Fourier-transform infrared spectroscopy (FTIR). The varying dose of MWCNTs (0.025–0.15 wt%) was incorporated into both PAO base oils to obtain the optimized lubrication behavior. The test results revealed that PAO 4 exhibited a reduction in friction coefficient (∼27%) and wear volume (∼88%) at a dose of 0.05 wt% and 0.025 wt% MWCNTs, respectively. However, in PAO 6, the minimum coefficient of friction and wear volume was obtained at a concentration of 0.075 wt% and 0.05 wt% of the additive. The results evidenced that PAO 6 based nanolubricants demonstrated the best frictional characteristics while attained the best anti-wear performance with PAO 4 based nanolubricants. For the better unveiling of the lubrication mechanism of MWCNTs, worn surfaces were characterized using various analytical techniques such as scanning electron microscopy (SEM), scanning probe microscope (SPM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron microscopy (XPS).
Homender Kumar and AP Harsha
SAGE Publications
This research paper addresses the optimization of various control parameters by using the Taguchi method to assess the tribological properties of PAOs based nanolubricants. The concentration of COOH-functionalized multiwalled carbon nanotubes (MWCNTs), applied load, sliding velocity and kinematic viscosity of polyalphaolefins (PAOs) were selected as process parameters or control factor. The MWCNTs at a varying concentration (0.025-0.15 wt.%) were blended separately in PAOs to formulate the nanolubricants. The tribological experimentations were performed by Taguchi’ L18 mixed orthogonal array using “ball on disc” type tribometer. The analysis of variance (ANOVA) was adopted to estimate the most prominent factors influencing the tribological performance of nanolubricants. The statistical results showed that the applied load, followed by a concentration of MWCNTs conferred the most significant impact on the frictional characteristic. In contrast, the kinematic viscosity of PAOs, followed by concentration of MWCNTs has been observed the most significant influencing factors on the antiwear properties of nanolubricants. The probabilistic rationale for the advancement in friction and wear properties were assessed through various analytical tools.
Homender Kumar and A. P. Harsha
Springer Science and Business Media LLC
Homender Kumar and A. P. Harsha
Informa UK Limited
The present work focused on the extreme pressure characteristics of different grades of polyalphaolefins (i.e., PAO 4, PAO 6, PAO 40, and PAO 100) with LaF3 nanoparticles as an additive. The LaF3 nanoparticles were synthesized by the sol-gel method and modified with oleic acid. The synthesized nanoparticles were characterized with various analytical tools, viz. X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Varying doses (0.025–0.15wt%) of synthesized nanoparticles were blended in all PAOs to prepare nanolubricants. The extreme pressure (EP) properties of nanolubricants were measured using a four-ball tester as per ASTM D2783 to find the last nonseizure load (LNSL), initial seizure load (ISL), just before weld load (JBWL), weld load (WL), and load wear index (LWI). The results revealed that the incorporation of LaF3 nanoparticles efficiently enhanced the EP properties of all PAOs. However, 0.15wt% of additive was the optimum dose in all PAOs, demonstrating the best EP behavior; that is, the highest LWI and lowest wear scar diameter (WSD) at ISL and JBWL. Numerous characterization techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and scan probe microscopy (SPM) were adopted to investigate the probabilistic rationale for the improvement in EP properties. ARTICLE HISTORY Received 11 July 2021 Accepted 2 November 2021
Homender Kumar and A. P. Harsha
ASME International
Abstract In the present investigation, the COOH-functionalized multi-walled carbon nanotubes (MWCNTs) having an outer diameter of 20–30 nm and length 1−2 μm were dispersed in four different grades of polyalphaolefins (PAOs; i.e., PAO 4, PAO 6, PAO 40, and PAO 100) at various concentrations (0.025, 0.05, 0.075, 0.10, and 0.15 wt%) to evaluate friction, anti-wear, and extreme pressure properties. The tribological test was conducted as per ASTM standard using four-ball tester. The test results showed that with the addition of MWCNTs, the friction and wear properties of PAOs had been improved significantly as compared to the base oils. It was also observed that MWCNTs exhibited excellent anti-wear properties than friction properties. The possible reasons for the improvement in friction and wear properties are discussed with the aid of various analytical tools.