Sharif Digital Repository

An extensive experimental investigation to study the effect of the reduced frequency and surface grit roughness on an airfoil oscillating in plunging motion has been conducted. The application of surface grit roughness simulates surface irregularities that occur on the wind turbine blades. Data were taken at a Reynolds number of 0.42*10* and at a range of reduced frequencies, k=0.03-0.1. Tests were conducted at plunging amplitudes of ±10cm and ±15cm and at mean angles of attack of 0°, 10° and 18°. It was found that the width of the hysteresis loop, position of the figure-8 shape, slope of the lift coefficient curve and maximum lift force have been influenced by both oscillation frequency and... 

Extensive experimental investigation was conducted to study the effect of leading-edge roughness on the state of the boundary layer of a wind turbine blade section. The application of surface grit roughness simulates surface irregularities that occur on the wind turbine blades. The measurements were done using multiple hot-film sensors and surface pressure transducers in both static and plunging oscillation of the airfoil. Frequency domain analysis was used to determine the state of the unsteady boundary layer  

A series of experiments were conducted to study the effect of leading-edge roughness on the state of the boundary layer of a wind turbine blade section using multiple hot-film sensors. The experiments involved static and dynamic tests, where airfoil motion was of plunging type oscillation. The application of surface grit roughness simulates surface irregularities that occur on the wind turbine blades. The measurements showed that increasing the angle of attack results in movement of transition locations toward the leading edge. Surface roughness moved the transition point toward the leading edge and caused early trailing edge turbulent separation, which resulted in reducing the effectiveness... 

Structural, microstructural and mechanical properties in roll bonding of AA5052 and polypropylene sheets have been evaluated in this study. The surface roughness of the AA5052 sheets, rolling temperature and the surface energy of polymer were selected as the bonding variables. The findings indicated that an increase in the surface energy of polypropylene by grafting maleic anhydride would result in higher bonding strength due to chemical interaction between the AA5052 and the maleic anhydride grafted polypropylene (PP-g-MAH). In fact, this reaction caused the formation of an interphase layer at the polymer side of the interface and the diffusion of aluminum into the PP-g-MAH layer. It was... 

Structural, microstructural and mechanical properties in roll bonding of AA5052 and polypropylene sheets have been evaluated in this study. The surface roughness of the AA5052 sheets, rolling temperature and the surface energy of polymer were selected as the bonding variables. The findings indicated that an increase in the surface energy of polypropylene by grafting maleic anhydride would result in higher bonding strength due to chemical interaction between the AA5052 and the maleic anhydride grafted polypropylene (PP-g-MAH). In fact, this reaction caused the formation of an interphase layer at the polymer side of the interface and the diffusion of aluminum into the PP-g-MAH layer. It was... 

Keratoconus (KC) is a progressive corneal disease. It is mostly characterized by corneal thinning and irregular steepening as well as formation of cone-shaped regions on the cornea. Amongst treatment modalities, implantation of Intrastromal Corneal Ring Segments (ICRSs) could decrease corneal surface irregularities. However, controversy exists over the selection of proper ICRSs. Here, the aim was to compare the effects of two sets of ICRSs. The ICRSs were identical both in cross-section and total arc length. The results showed that under normal physiological range of intraocular pressures (IOPs), the two selected ICRSs caused slightly different deformations in the same in-silico keratoconic...