Feb'19

Welcome to The IUP Journal of Mechanical Engineering

Focus

Design and development of large wind turbine blades is a challenging job due to a variety of requirements related to economic, logistic, manufacturing, and technical constraints. Among the technical requirements, shape optimization is an important part in the design of wind turbine blades. New-Age Flatback turbine blade is a recent development, and it consists of a blunt trailing edge—which generates a larger moment of inertia—and has an aerodynamic performance, a little bit better than the common profiles. The paper, “Modeling and Simulation of a 3 MW Wind Turbine Blade for Determination and Analysis of Flow Characteristics”, by Amool A Raina, Saeed Farokhi and Kyle Wetzel, presents a comprehensive 3D analysis of a rotating wind turbine to predict the aerodynamic behavior for a large rotor blade structure. The authors have subjected the blade model with length of 56 m, maximum chord section of 4.2 m and prebend of 1.2 m (added primarily for structural reasons) to understand the flow characteristics in the hub/transition region of the blade. The authors have presented a full-scale analysis of large wind turbine blades to solve the fluid dynamic problem with the help of a finite-volume, Reynolds-Averaged Navier–Stokes (RANS) solver. A comparison of the results obtained from RANS with those obtained from Blade Element Momentum (BEM)-based methods shows that RANS simulation resulted in a higher energy capture as compared to predictions obtained from BEM.

Laser-based machining methods like laser cutting, welding, cladding, engraving, surface treatment and drilling have wide applications in machining various materials. Laser engraving finds enormous applications in every industry ranging from automotive to aerospace. Due to the increasing demand for rapid prototyping and 3D printing technologies, it has become quite essential for industries to look for better techniques and design, without compromising on quality standards. In the present-day scenario, industrial equipment is becoming compact, miniaturized and smarter. The paper, “Design and Fabrication of Laser Engraving Machine”, by Rahul Mehra, Sachin Mohal and B Lonia, presents details of a low-cost rapid prototype laser engraving machine. The 3D modeling and simulation of this machine is done using CREO 2.0 software. A 15 W diode laser is used to engrave various materials. The authors have validated the machine by performing dimensional and dependency tests. Pilot experimentation has been carried out on GFRP composites. Undoubtedly, the indigenously developed machine has cost-effectiveness and better performance in comparison to currently available laser engraving machines.

Ever increasing prices of petroleum and coal have thrown challenges for efficient ways of generating energy. Heat exchanger as a device of energy utilization is widely accepted and applied to chemical process, petroleum, power, refrigeration, food processing, etc. Entransy effectiveness is a measure of the irreversibility of the heat transfer process in the heat exchanger. The term ‘entransy’ is a recently coined one, used to define the efficiencies of heat transfer processes and to optimize heat transfer processes. More dissipation of entransy implies higher degree of irreversibility in heat transfer process. The paper, “The Effect of Optimum Entransy Dissipation Number on the Performance of Heat Exchanger”, by Roopesh Tiwari and Govind Maheshwari, presents a new concept of optimum entransy dissipation number which is defined as the ratio of actual entransy dissipation to the optimum entransy dissipation. The optimum entransy dissipation number is found to decrease for both parallel flow and counter flow, with the increase in the Number of Transfer Units (NTU) for a given heat capacity rate ratio. The authors have found that the counter flow arrangement yields a better result, as compared to parallel flow arrangement. Further, based on a comparison of the variation of optimum entransy dissipation number with the variation of entransy dissipation number, the authors have concluded that optimum entransy dissipation number can be used to evaluate the heat exchanger performance.

The next paper, “Perturbation Analysis of Glassy Alloy Film Formation”, by Rahul Basu, presents a coupled set of equations describing heat and mass transfer during phase transformation, incorporating surface convective effects. A relation is found for the effect of the glass transition temperature versus the boundary layer thickness for several alloys in various groups of the periodic table. Physically, a boundary layer is found to exist between liquid and solid by foundry technologists, which is referred to as ‘mushy zone’. The author has obtained the rate of transformation between the liquid and solid phase by solving the Moving Boundary Problem (MBP).

The last paper, “Exergy Analysis of Gautami Combined Cycle Power Plant, India: A Case Study”, by Venkata Ravi Ram Pinninti, T V K Bhanuprakash, Ramamurthy Dwivedula and Rama Jonnada, presents a case of Gautami combined cycle power plant, Andhra Pradesh, India. Using theoretical thermodynamic analysis and actual real plant operational data, the loss due to exergy in different cycle components is calculated. The case also presents the influence of critical parameters like compressor discharge pressure and gas turbine inlet temperature on exergy destruction in different combined cycle components.

S V Srirama Rao
Consulting Editor

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Article   Price (₹) Buy
Modeling and Simulation of a 3 MW Wind Turbine Blade for Determination and Analysis of Flow Characteristics
50
Design and Fabrication of Laser Engraving Machine
50
The Effect of Optimum Entransy Dissipation Number on the Performance of Heat Exchanger
50
Perturbation Analysis of Glassy Alloy Film Formation
50
Exergy Analysis of Gautami Combined Cycle Power Plant, India: A Case Study
50
     
Contents : (Feb' 2019)

Modeling and Simulation of a 3 MW Wind Turbine Blade for Determination and Analysis of Flow Characteristics
Amool A Raina, Saeed Farokhi and Kyle Wetzel

The paper discusses the strategy for aerodynamic prediction and analysis of a 56 m blade using Computational Fluid Dynamics (CFD) tools. The aim of this study is to simulate the flowfield around a 3 MW wind turbine blade to study the flow physics dominated by the three-dimensional effects. This blade incorporates flatback airfoils on the inboard region of the blade used to improve aerodynamic performance in the root region. In order to reduce computation time and complexity, only one-third of the domain is modeled and a periodic boundary condition is imposed on the 120° periodic faces. A k-? SST turbulence model is used as a solver for this simulation. Several features pertaining to 3D flowfield behavior are captured and studied. A comparison is made of the results obtained from RANS with those obtained from Boundary Element Method (BEM)-based methods. The flow past the flatback regions of the blade did not separate at the sharp edges of the flatback corners, as predicted by 2D simulation due to the presence of a dominant radial flow component in the span-wise direction which caused the flow to wrap around the trailing edge of the blade without corner separation. The paper presents a comparison of the inflow angles from CFD to those predicted by BEM.


© 2018 IUP. All Rights Reserved.

Article Price : Rs.50

Design and Fabrication of Laser Engraving Machine
Rahul Mehra, Sachin Mohal and B Lonia

Laser engraving machine is used to mark various pictures and symbols on different materials. The laser engraving setup is advantageous due to its low operational cost, lightweight, portability and easy-to-learn features. The paper fabricates a low cost rapid prototype laser engraving machine. The proposed setup has been applied to Glass Fiber Reinforced Plastics (GFRP) composites, plastics, wood, cardboard, etc., to yield desired profile, contour, information and various drawings. Moreover, developed laser engraving setup has high precision and processing efficiency. Laser engraving technique involves color change of the surface due to thermal energy emerged by the laser beam. The 3D modeling and simulation of this machine is done using CREO 2.0 software. A 15 W diode laser is used to engrave the various materials. Various advanced software and hardware like Inkscape, Arduino, GRBL controllers and microcontrollers are assembled together, further leading to the execution of the final engraving. Validity of the machine has been verified by performing dimensional, dependency and co-ordinate tests. Finally, pilot experimentation has been carried out on GFRP composites.

© 2018 IUP. All Rights Reserved.

Article Price : Rs.50

The Effect of Optimum Entransy Dissipation Number on the Performance of Heat Exchanger
Roopesh Tiwari and Govind Maheshwari
The paper introduces a new concept of optimum entransy dissipation number to evaluate the heat exchanger performance. The analytical model presented is based on entransy which represents the heat transfer ability of an object. The lower the entransy dissipation, the higher the heat transfer ability of an object. The parallel flow and counter flow arrangements are analyzed. The analysis shows that the optimum entransy dissipation number, which is a non-dimensional parameter, has a decreasing trend with the increasing number of transfer units for both parallel flow and counter flow arrangement. The counter flow arrangement yields better result compared to parallel flow arrangement. The variation of optimum entransy dissipation number is compared with the variation of entransy dissipation number. The results show similar pattern; hence, the optimum entransy dissipation number can be used to characterize the heat exchanger performance.


© 2018 IUP. All Rights Reserved.

Article Price : Rs.50

Perturbation Analysis of Glassy Alloy Film Formation
Rahul Basu

A coupled set of equations describing heat and mass transfer during phase transformation is formulated incorporating surface convective effects. These equations, which are nonlinear due to the moving interface, are linearized and decoupled. The effects of the Biot, Fourier and Stefan numbers are analyzed through small parameter expansions. Solutions obtained via this artifice allow closer examination of surface effects on the boundary layer of the phase transformation. A relation is found on the effect of the glass transition temperature versus the boundary layer thickness for several alloys in various groups of the periodic table. Earlier work is analyzed in the light of the present analysis.


© 2018 IUP. All Rights Reserved.

Article Price : Rs.50

Exergy Analysis of Gautami Combined Cycle Power Plant, India: A Case Study
Venkata Ravi Ram Pinninti, T V K Bhanuprakash, Ramamurthy Dwivedula and Rama Jonnada

The continual need to optimize costs and the recent competitive pressure from renewables have seen renewed focus on improving and optimizing plant components’ efficiency. Combined cycle power plants are better from thermal efficiency point of view compared with coal-based power plants. Exergy analysis offers better alternative to energetic analysis based on simpler model of energy balance only. Identifying system energy losses is easier using exergy analysis, making it a better analytical tool. The paper presents a case study of exergy analysis of Gautami combined cycle power plant. Component level theoretical analysis is done first and applied to the operational data from the plant. The results showed that the gas turbine combustion chamber has the highest exergy loss of 33%. Impact factors like ambient temperature, pressure ratio, turbine inlet temperature and heat recovery steam boiler are also considered on the exergy losses of the power plant.


© 2018 IUP. All Rights Reserved.

Article Price : Rs.50

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