Sourabh Kumar

Design and Analysis of Wind Turbine Blades: Winglet, Tubercle, and Slotted

Energy is the heart of today’s civilization and the demand seems to be increasing with our growing population. Alternative energy solutions are the future of energy, whereas the fossil-based fuels are finite and deemed to become extinct. The design of the wind turbine blade is the main governing factor that affects power generation from the wind turbine. Different airfoils, angle of twist and blade dimensions are the parameters that control the efficiency of the wind turbine. This study is aimed at investigating the aerodynamic performance of the wind turbine blade. In the present paper, we discuss innovative blade designs using the NACA 4412 airfoil, comparing them with a straight swept blade. The wake region was measured in the lab with a straight blade. All the results with different designs of blades were compared for their performance. A complete three-dimensional computational analysis was carried out to compare the power generation in each case for different wind speeds. It was found from the numerical analysis that the slotted blade yielded the most power generation among the other blade designs.Copyright

Wind Turbine Blade Design and Analysis With Tubercle Technology

The objective of this project is to construct a CAD model for tubercle wind turbine. Once the model is developed a complete CFD analysis of the flow pattern around the wind turbine will be carried out. The main objective of the study is to analyze and compare the performance of the tubercle wind turbine with the usual wind turbine. The power developed by both the turbine blades can be compared to support the use of tubercle. The tubercles are very effective for increasing the lift without stalling. The main objective of this project is to study the aerodynamic advantages of tubercle turbine blade. The effort will be to compare the obtained results with the straight blade of the same airfoil. This will provide insight into the advantages of using the tubercle blade. This technology being new the study is done numerically to study the overall effect of the tubercle.Copyright

Experimental and Numerical Evaluation of Geometric Modifications in Gas Turbine Blade Cooling Channel

Cooling channels are essential components of the modern gas turbine engines. Enhanced cooling techniques are allowing for increase in firing temperatures and thereby improving power and efficiency. Air bled from the compressor is passed through serpentine passages within the blade to take away the heat and keep the blade under operating temperatures. Heat transfer in the channel can be improved by increasing the turbulence in the coolant flow. U-Bends in the serpentine channels cause secondary flow and Coriolis effects. Apart from this, the channel walls are impregnated with turbulators such as ribs, pins and dimples. These turbulators cause flow disturbance near the wall improving the heat transfer. Designing the cooling system requires detailed understanding of the flow patterns in the channel. Numerical techniques help understand the flow in detail providing 3-dimensional velocity profiles and other parameters. Experimental data helps validate the numerical models and improves the reliability of the numerical results. In this research, experiments were performed to determine the Nusselt number distribution in a cooling channel and numerical simulations were performed to compare and predict the heat transfer in other channels.

Modelling of energy usage for the refining of ethanol from corn

A mathematical model is developed and presented for calculating the energy usage and costs for the dry milling corn-ethanol production process. The model is formulated into a spreadsheet to facilitate the study of the process. While considering the whole process, the model focuses on the primary energy-consuming cooking and distillation processes. This model is a feed-backwards model, which means process input requirements are calculated based on user-entered values for total annual plant production and various process parameters. Based on these input requirements, the total energy usage and the cost and amount of fuel used during the process are calculated. The accuracy of the model was verified through comparisons between modelling results and published data. This model can be used as a source for investigating other potential energy sources, such as the incorporation of solar energy and wind energy, for use in the ethanol production process.

Numerical Comparison of Heat Transfer and Pressure Drop in Gas Turbine Blade Cooling Channels With Dimples and Rib-Turbulators

In order to enhance the performance of a gas turbine and to maintain the blade material within operating temperature range, cooling channels are made within the blade materials that extract the heat. The walls of these cooling channels are usually enhanced with some sort of turbulence generators — ribs and dimples being the most common. While both the geometries provide improvement in enhancing the heat transfer, dimples usually have a lower pressure drop. It is essential to improve the heat transfer rate with a minimal pressure loss. In this study, the heat transfer and pressure loss are determined numerically and combined to show the effect of both in channels with ribs and dimples on one wall of the channel. Similar geometric and boundary conditions are used for both the turbulators. Reynolds numbers of 12,500 and 28,500, based on the hydraulic diameter are used for the study. The Reynolds-Stress Model was used for all the computations as a turbulence model by employing Fluent.Copyright

Experimental Analysis of the Heat Transfer Variations Within an Internal Passage of a Typical Gas Turbine Blade Using Varied Internal Geometries

This paper describes the experimental analysis of the heat transfer rate within an internal passage of a typical gas turbine blade using varied internal geometries. This method of alteration, using rib turbulator’s within the serpentine cooling passages of a hollow turbine blade, has proven to drastically cool turbine blades more significantly than a smooth channel alone. Our emphasis is to determine which rib geometry will yield the highest heat transfer rate, which was examined in the form of a comparison between theoretical to experimental Nusselt numbers. For testing purposes, an enclosed 2 in. × 2 in. square Plexiglas channel was constructed to model an internal cooling passage within a turbine blade. Silicon heat strips, wrapped in copper foil, were placed on the bottom surface of the channel to ensure even heat distribution throughout. To measure internal surface temperatures, thermocouples were placed on the surface of heat plate as well as in the opening of the channel throughout. The four different rib geometries which were individually wrapped in copper foil were then placed on top of the heating element. To compare the rib geometry results with a control, a test was run with no ribs. To simulate turbulent air flow through the channel, a blower supplied velocities of 23.88 m/s and 27.86 m/s. These velocities yielded a Reynolds number ranging between 70,000 and 90,000. Final results were found in the form of the experimental Nusselt number divided by the theoretical Nusselt number, a standard when comparing surface heat transfer rates. The 60 degree staggered arrow geometry pointing away from the inlet and outlet (geometry 4) proved to create the highest heat transfer rate through the way it produced turbulent air flow. The average Nusselt number of this design was found to be 718.2 and 868.3 for 23.88 and 27.86 m/s respectively. From the calculated data it was found that higher Nusselt numbers were more prone to occur in higher air velocities.Copyright

Numerical Simulation of Two Pass Gas Turbine Blade Internal Cooling Channels With 90 Degree Varying Height Ribs

Improvement in thermal efficiency of gas turbine can be obtained by operating it at high inlet temperatures. In addition to improving the performance, the cons of high inlet temperature is high thermal stresses on the turbine blades. To improve life and performance of the blade, improved cooling technologies are desired. The main objective of this paper is to perform computational analysis of the ribs with varying height and compare this with 90 degree ribbed channel and smooth channels. The numerical analysis is carried out using ANSYS-Fluent, a flow modeling simulation software. The flow is assumed to be steady state and flow turbulence is modeled using the k-e with Standard Wall Functions. Local heat transfer and friction loss in a square duct roughened with 90 degree ribs with varying height is investigated for different Reynolds number. The pitch of the rib is considered to be 10 times the height of rib which is 0.0635 m. The square cross section of the channel is .0508x .0508 m2. The pitch of rib to rib height ratio varies from 10 to 20 at the center of the channel. There is a rib considered at the turn section as well. The numerical simulation produced higher heat transfer for the varying height ribs as compared to 90 degree ribbed channel and smooth channel.Copyright

Determination of Torque-Strain Relationship in an Impact Wrench

The impact wrench driver is used to deliver increasing torque with time. In most applications, the torque required needs to be at a predetermined level. The present method of achieving this is based on the skill of operator. The operator ball parks the torque and later measures with a torque wrench, making any necessary adjustments. To achieve a more accurate torque adjustment, it is desired to have a torque read out on the impact wrench. This can also be used to shut off the device when the desired torque is produced. This is achieved by measuring the strain in the stationary planetary gear inside the driving mechanism of the impact wrench. After conducting a series of experiments, the relation between the torque and strain is determined and this relation is used for torque readout. Torsional strain gauge is placed on the gear body. The strain is measured at various torques to formulate relation between the two. To provide a constant torque a friction plate mechanism is used in the experimental setup.

Computational Study of Heat Transfer Distribution in a Square Channel with Rib Turbulators and Bleed Holes

The objective of this study is to clearly understand the flow and the heat transfer mechanisms in a gas turbine cooling system by performing a computational analysis of the turbulent heat transfer of an internal ribbed channel. To test the performance, a square duct with rectangular turbulence promoting ribs oriented at 60o inverted V ribs and placed at regular intervals on one of the walls with bleeding holes has been simulated. The normalized Nusselt number obtained from simulation are validated against experiments. The Reynolds number is set at 12,500 for both simulation and experiment. The three-dimensional turbulent flows and heat transfer are numerically studied by using a turbulence model, nonlinear low-Reynolds number k-ω model. In k-ω ω ω ω model the cubic terms are included to represent the effects of extra strain-rates such as streamline curvature and threedimensionality on turbulence normal and shear stresses. The finite volume difference method incorporated with the higher-order bounded interpolation scheme has been employed in the present study. The outcome of this study helps determine the best suitable turbulence model for future studies.