Papers Posted on - Jun / 2020


Author Name Apurba Kumar Roy
PDF Download PDF
DOI http://dx.doi.org/10.11127/ijammc 2020.06.01
Paper Title Cooling of Rotating Turbine Blades – A Novel Approach
Abstract
Gas turbines are required to function at a higher temperature for better thermal efficiency hence cooling of rotating blades of gas turbines is very essential for longevity and more efficient operations. In order to achieve the same film cooling was employed injecting cold air into the bulk fluid boundary layer. The cool air spreads over the blade material surface and isolates the surface from getting excessive heated. Although a volume of work has been already done on the same but under static condition but in practice since the blade would be rotating with certain speed hence it was required to study the cooling effectiveness under dynamic situation. Simulation study was done providing a rotation at two different rpm and it was observed that with backward injection of cooling air, cooling effectiveness, corelated in terms of area covered was much better than the forward one. It also indicated that the effectiveness decreases with increase in rpm as the time available for heat transfer gets reduced. The work provides a complete picture with all parameters considered.
Keywords
Gas Turbines, Rotating Blades, Film Cooling, Bulk Fluid Boundary Layer, Forward Injection of Cooling Air, Backward Injection of Cooling Air, Cooling Effectiveness, Film Hole Configuration, Surface Curvature, Shaped Holes, Orientation of Cooling Holes, Blowing Ratio, Density Ratio, Rotation of The Blades.
Author Name Apurba Kumar Roy
PDF Download PDF
DOI http://dx.doi.org/10.11127/ijammc 2020.06.02
Paper Title Performance Evaluation of a Low Head Hydraulic Air Compressor: A Prospective Source of Renewable and Green Energy
Abstract
Hydraulic Air Compressor is a device that utilizes the energy of falling water, with entrained air bubbles, onto a downcomer pipe to compress the air within it. This concept to harness hydropower to compress air and its use dates back to the Iron Age. It was discarded after the evolution of fossil fuel due to its bulkiness. The concept has revived again after the global cry for non-conventional renewable source of energy. In this work an experimental setup was made to study the hydrodynamic characteristics of downward air-water two-phase flow through the downcomer pipe of the Hydraulic Air Compressor. It was observed that the results were quite comparable to the theoretical predicted values and Hydraulic Air compressor apart from has many useful interesting applications can also be used as an alternative air compression system.
Keywords
Air Bubble, Air Entrainment, Conductivity Probe, Cone, Downcomer Pipe, Hydraulic Air Compressor, Nozzle, Separator.
Author Name Sudhir Kumar Kashyap
PDF Download PDF
DOI http://dx.doi.org/10.11127/ijammc 2020.06.03
Paper Title Failure Analysis Of FRP Composite Bonded Socket Joint
Abstract
Pipes and pipe joints are the backbone of many engineering applications such as oil and gas industries, mining applications, aerospace industries, structures, automotive industries etc. Adhesively bonded laminated Fiber Reinforced Polymer ( FRP) composite pipe joints have many advantages over conventional pipe joints (e.g. welded), as adhesive joints are less corrosive and this type of joint provide more uniform load transfer. In the present work finite element simulation of functionally modified adhesive bonded FRP composite socket joint has been carried out. The grading is given along bond-length for bonded socket joint of laminated Fiber Reinforced Polymer composite pipes. The loading condition is axial tensile at one free end and other end is constrained (fixed in all directions). The geometries and boundary conditions are taken from [1]. Different kinds of failures in the socket joint such as cohesion failure in the adhesive mid layer, adhesion failure in the tube-adhesive interface and adhesion failure in socket-adhesive interface have been analyzed using different failure criteria as Tsai-Wu failure criteria for adhesion failure and parabolic yield criteria for cohesion failure. Failure indices of the socket joint has been determined and critical region of the joint has been found at the edges and near the middle of the bonded tubular socket joint. Different functional grading has been applied and failure index profiles for different modulus functions have been drawn to compare these profiles obtained with failure index for isotropic adhesive to determine an appropriate function for modulus grading which reduces the stress concentrations effectively and increases the strength and life of the bonded tubular joint. Quadratic (parabolic), Biquadratic and Cosine functions are applied to compensate the stress pinnacle or stress singularities. The stress peaks at edges and near the middle of the socket joint are found to be more than the other portion of the socket joint. Flexible adhesives having lowest values of elastic modulus at edges and near the middle of the joint are used to reduce the stress peaks, and highest values of elastic modulus are the regions where stress values are less we used stiffer adhesive.
Keywords
FGM adhesive, Bonded joint, Cohesion failure, FEM, FRP composite.