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Centrifugal (radial flow) turbines are widely used in various industries, including power generation industries, so the study on them is of particular importance. The aim of this study was to investigate the thermodynamic properties of fluid flow in Trailing Edge (TE) and (LE) Leading Edge. For this purpose, first, the rotor (impeller) of the radial flow turbine was designed based on some design data such as flow rate, number of blades, rotational speed, diameter and length of the impeller, and then the designed rotor was simulated in 3D. The simulation done in the pressure based method and the turbulence model is SST and the rotational speed was 140,000(RPM). The results showed that the pressure, temperature and enthalpy in TE are less than LE and the areas close to the hub have the highest pressure. Another phenomenon observed is that in the section LE we see the separation of the flow from the blade surface, which then approaches the blade surface again and follows a relatively regular path,so the entropy in TE is greater than LE. At the end, the results of numerical solution were compared with valid data and the error rate and its reasons were discussed.

The purpose of this study was to investigate the effect of the number of spiral paths on the spray cone angle, discharge coefficient and droplet diameter in pressure-swirl atomizer with spiral paths using numerical and experimental methods. Initially, the injector was designed and manufactured based on some assumptions such as operating fluid type, pressure difference, spray cone angle and mass flow rate and then tested. Comparison of test results with design assumptions showed that mass flow rate and spray cone angle and discharge coefficient were 5%, 13.25% and 4% error, respectively. Then, numerical solution method was used for numerical investigation of the influence of geometric parameters. To simulate the two-phase flow, the fluid volume fraction model was used. The numerical solution of mass flow rate and spray cone angle and discharge coefficient showed 7.4%, 9.5% and 11.76% error, respectively. The results showed that the pressure-swirl atomizer with spiral paths has a conical shape and is hollow. Also, the total velocity and its components on the edge of the spray cone have the highest value. Investigations showed that at constant mass flow rate with increasing the torsion of spiral path, the total radial, axial and tangential velocities increased, which increased the spray cone angle and decreased the droplet diameter.

Optimum implant positioning and technique used for its alignment are vital parameters to improve clinical results. Visual cues and jigs are utilized in the recent surgical techniques, which lead to some errors in the flexion-extension axis identification. Surgeons have used computer-assisted surgery for the alignment of the hip, knee, and shoulder. However, there is a restricted application of this technology to the elbow. In this study, a technique was used to model a drill guide template to precisely place an implant in the bone. The computed tomography dataset was used to construct four different elbow bones, and an elbow implant was modeled. The surgical drill guides were designed based on the computed tomography data. The drill guide templates and constructed bones were fabricated, using a 3D printer. The accuracy of the surgical guides was validated experimentally. The results showed that the mean deviations between the achieved and planned positions of the hole at the bone apex and base of bones were less than those reported in previous studies in both medial/lateral and posterior/anterior positions. The low positioning errors observed in this study proposed that the implant’s location can be precisely aligned to its target using the introduced technique.

Loosening of an implant is the main complication after total elbow arthroplasty. The design parameters of the implant are a factor that contributes to the loosening of the implant. In this study, the correlation of loosening and geometry of the elbow implant component was investigated using the finite element method. Image processing software was used to construct elbow bones. Humeral and ulnar components were modeled with various cross-sections and flanges using modeling computer-aided design software. Modeling of all stems was based on conventional cemented fixation. Axial torsion and Anterior-posterior force were applied to the articular surface. Zero-displacement was applied to the proximal humerus and distal ulna. Bone graft was used between the flange and distal humerus bone. The stress shielding of bones and micro-motion were obtained in cement-implant-bone interfaces. Results showed that humeral and ulnar stems with modified diamond cross-section observed less micro-motion in the cement-bone-implant interfaces and as well as the least stress shielding in the distal humerus and proximal ulna compared to others. Furthermore, the modified flange, concave, transferred the least micro-motion to the bone-cement-implant interface and less stress shielding in distal humerus in comparison with trapezium and rectangular ones. This computational analysis represented a step in quantifying the role of interface micro-motion stress shielding of bone in initiating elbow implant loosening. A reduction of micro-motion and stress shielding through design modifications may improve the clinical outcomes.

Nowadays, root osseointegrated dental implants are used widely in dentistry mainly for replacement of the single missing tooth. The success rate of osseointegrated dental implants depends on different factors such as bone conditions; surgery insertion technique, loading history, and biomechanical interaction between jawbone and implant surface. In recent years, many studies have investigated design factors using finite element analysis with a concentration on major parameters such as diameter, pitch, and implant outlines in the distribution of stress in the bone-implant interface. There is still a need to understand the relationship and interaction of design factors individually with stress distribution to optimize implant structure. Therefore, the present study introduced a new dental implant and investigated the effect of design parameters on stress distribution. The finite element modeling was developed to facilitate the study with a comparison of design parameters. Boundary and loading conditions were implemented to simulate the natural situation of occlusal forces. Based on results, V-shape threads with maximum apex angle caused a high rate of micro-motion and high possibility of bone fracture. Low Von-Mises stress was associated with low bone growth stimulation. Besides, small fin threads did not integrate with cancellous bone and consequently lower stress accommodation. V-5 fin had no extraordinary performance in cancellous bone. Small surface areas of fins did not integrate with the surrounding bone and high-stress concentration occurred at the tail. These fins are recommended as threads replacement. It was concluded that the implant structure had less influence on stress distribution under horizontal loading.