Shravan Koundinya Vutukuru | Riga Technical university (original) (raw)

Papers by Shravan Koundinya Vutukuru

Lecture notes in mechanical engineering, 2021

Latvian Journal of Physics and Technical Sciences, Mar 30, 2021

An approximate method for analysis and synthesis of moving rigid bodies (prisms) in the airflow w... more An approximate method for analysis and synthesis of moving rigid bodies (prisms) in the airflow without using numerical methods of space-time programming techniques is described by applying a fluid (air)-rigid solid body interaction concept for engineering applications through a straightforward mathematical model. The interaction of rigid body (prism) and air is encountered in different cases: moving body (prism) in the air; stationary bodies (prism) in the airflow; moving body (prism) in the airflow. The complicated task of rigid body (prism) and air interaction is simplified by using superposition principles, i.e., by taking into account the upstream and downstream rigid body (prism) and air interaction phenomenon, which has been found to be different under varying speeds. Numerical results obtained for various forms of prisms are shown for constant air-speed, where the steady state Reynoldsaveraged Navier-Stokes (RANS) equation is solved by using k-ε realizable turbulence model. A detailed explanation to support the proposed approximate method is given by using numerical results obtained in ANSYS computations. All equations are formed based on laws of classical mechanics; the interaction of viscous forces is neglected in forming the mathematical model. Numerical results for different model prisms are compared and the theoretical results discussed in detail. The mathematical model in the present paper is applicable only to bodies that undergo a rectilinear translation motion. In the final part of the present paper, the proposed method is used in the synthesis and optimization task of energy extraction by considering the motion of a variable parameter prism in the airflow.

21st International Scientific Conference Engineering for Rural Development Proceedings

The interaction of the lateral surface of an axially cylindrical prism with the fluid flow is stu... more The interaction of the lateral surface of an axially cylindrical prism with the fluid flow is studied. The prism moves in a translational motion (without rotation) in a fixed fluid, such as air. The effectiveness of such a reduced interaction analysis is important in reducing vehicle drag as well as increasing the speed of technical sports vehicles. Accordingly, the task of increasing the interaction forces involves extracting energy from the fluid. In the mathematical problem, the force of resistance of the prism to fluid movement, its minimum or maximum value, is chosen as the optimization criterion. The interaction between the prism and the fluid is described in an unconventional way, without using the concepts of drag and lift forces, but using the relationships of classical mechanics. For this purpose, the interaction of the prism with the fluid is divided into two zones: the pressure zone (in front of the prism) and the suction zone (at the back of the prism). Interactions with changes in the amount of motion of a fluid in a differential form are obtained. The relationships found are integrated in the simplest cases: for example, when the surfaces of a prism are broken planes. Two dominant forms of the prism are considered: the surfaces are only convex or the surfaces are only concave. Parametric optimization problems are solved numerically with a computer. As a result, optimal shapes are obtained for the minimum criterion and the maximum criterion. The main result of the research is the application of a new theory of fluid mechanics, which allows analytical or numerical solving of analysis, optimization and synthesis problems with the obtained formulas, without the use of space time programming, which would need to change the object shape, flow rate and direction in almost every integration step.

The goal of the study was exploring the possibility of energy harvesting from the vibration of th... more The goal of the study was exploring the possibility of energy harvesting from the vibration of the body in the air focusing on the example of the flat plate. Theory suggests that at certain conditions and excitation parameters vibrations of the system increase so that energy can be produced. Additional energy can be extracted from flutter motion – an aeroelastic instability that results in self-excited oscillation. The flutter is usually considered as the negative side effect that engineers try to eliminate, but in this study, we look for ways how to benefit from it. The flat plate is fixed in a flexible suspension and is affected by the air flow. The suspension is designed in such a way that the plate does not rotate but moves in a translational motion. First, the air flow was set up in different ways to study the response of the plate. Using computer modelling in MathCAD software, the movement of the object in the air flow was analysed. Some areas of the system at specific excitat...

The paper is devoted to the analysis of a non-stationary rigid body interaction in a fluid flow. ... more The paper is devoted to the analysis of a non-stationary rigid body interaction in a fluid flow. Initially, an approximate method for determining the forces due to fluid interaction with the rigid body is offered. For this purpose, the plane movement of a mechanical system with an infinite DOF (degrees of freedom) is reduced to 5 DOF motion: 3 DOF for the body and 2 DOF for the areas of compression and vacuum in fluid flow. Differential equations of non-stationary motion are formed by the laws of classical mechanics. The use of an approximate method has been quantified by computer modelling. The average difference in results was found to be small (< 5%). The analysis of the fluid (air) interaction is carried out for a rigid body of two simple geometries flat plate and diamond. The results obtained are used to refine the parameters of the proposed approximate method that is addressed in the present study for fluid interaction with the non-stationary rigid body. Theoretical results...

Šķidruma plūsmas un ķermeņa un šķidruma mijiedarbības pētījumiem ir sena vēsture, taču interesant... more Šķidruma plūsmas un ķermeņa un šķidruma mijiedarbības pētījumiem ir sena vēsture, taču interesanti ir tas, ka joprojām nav izpētītas nestacionāras ķermeņa kustības un nestacionāras šķidruma mijiedarbības parādības. Risinājums ir ļoti sarežģīts, jo pastāv milzīga vienādojumu sistēma, kas sastāv no visiem telpiskā uzdevuma elementiem, kas ir savienoti kopā starp visiem telpas un laika posmiem. Turklāt, apsverot telpiskos aspektus parciālo diferenciālo vienādojumu sistēmas risināšanai, virkne sarežģījumu rodas no risinājuma metodes veida (galīgas starpības, galīgi tilpumi, galīgi elementi) un arī no mezglu veidošanas metodēm (kustīgas, strukturētas vai nestrukturētas). Lai gan ir pieejami mūsdienīgi komerciāli šķidruma un struktūras mijiedarbības modeļi, tie aprobežojas ar vienkāršiem ķermeņiem un prasa biežas tīkla maiņas metodes, kas ir laikietilpīgas un dārgas skaitļošanas procesos. Promocijas darbā īpaši pievērsta uzmanība tikai cieta ķermeņa un šķidruma (gaisa) mijiedarbībai, un n...

19th International Scientific Conference Engineering for Rural Development Proceedings, 2020

In engineering, for many practical applications fluid-body interactions are commonly encountered ... more In engineering, for many practical applications fluid-body interactions are commonly encountered and thereby these interactions have to be extensively studied. Though this body-fluid interaction is studied in the past, the concept of interaction analysis, form optimization relating to axis symmetry geometries till date mostly need to be further explored. The present work is devoted to the analysis of fluid (air) to body (prism) interaction, form (or shape) optimization taking into account various criteria and energy extraction from air flow by using an axial symmetric body (circular disc shaped geometry with alternate perforated quadrants) with plane symmetry (cylinders) is considered. A simplified mathematical model for engineering calculations is proposed. The model is based on the concept of pressure (compression) and suction zones, when a body is subjected to fluid (air) flow. Initially, all calculations are performed for the geometry under study in constant dimensions. Further, for better efficiency of the overall system, the system parameters are changed in constant continuous steps by a detailed analysis of the fluid-body interaction response surface. The mathematical model has the following assumptions: the fluid (air) flow is laminar, non-compressible (density constant) and the fluid (air) viscous is ignored. All the results obtained are discussed in graphs and explained. Three-dimensional fluid flow simulations are performed in ANSYS, steady state RANS is solved using Kε realizable turbulence model, the interaction force (Drag) is obtained for the geometry under study. Finally, the results relating to form (or shape) optimization and the application of the concept are widely discussed.

19th International Scientific Conference Engineering for Rural Development Proceedings, 2020

The impact of granules which are of various form, size and densities against a vibrating prism is... more The impact of granules which are of various form, size and densities against a vibrating prism is analyzed. The analysis is performed in a two-dimensional plane (2D), assuming that the prism perpendicular to the plane is symmetric with the given constant height. In the description of the interactions, classical mechanics are used to describe the impact of granules or granule flow against a moving obstacle (vibrating prism). The air viscosity is not taken into account and thereby the present work offers simplified analytical solutions for engineer calculations through a straight forward mathematical model. In the interaction of granules with the obstacle, the impulse restitution coefficient is applied in the normal direction. The no-slip rule or the dry friction coefficient for slip, respectively, is applied to the interaction in the tangential direction. The analysis uses the superposition principle for individual airflow and for each granule fraction. As a result, for a continuous environment, it is possible to divide the interaction by the center of mass of several layers in the region of motion. The results obtained show the distribution of fractional flows, taking into account that there is a suction zone just behind the prism. Despite the complicated interactions of the components of the environmental fractions, the developed analytical method allows analytical prediction and calculation of the separation motions. The equipment for the experiments is 3D printed, and the experiments were performed to measure the flow speed of the medium using a bottom open cone container.

World Journal of Engineering and Technology, 2018

Computations and Experiments were performed to get an understanding of the flow field around a re... more Computations and Experiments were performed to get an understanding of the flow field around a rectangular supersonic air intake with pointed cowl [90˚] at different back pressures for Mach 2.2. The effect of Cowl shape on the ramp surface pressure distribution is discussed and compared with existing V-Notch [90˚] intake model at free exit condition. It was found that using pointed cowl [90˚] intake model, a better pressure recovery was achieved compared to the V-Notch [90˚] intake model at Mach 2.2. Both Pointed and V-Notch intake models showed good starting characteristics. For change in back pressure, the occurence of normal shock, flow separation zone and flow reversal were observed. All experiments are performed only for the Pointed cowl [90˚] intake model. All the 3-D computations were performed by using software available at B.I.T, Mesra, Ranchi.

Transport and Aerospace Engineering, 2017

Experiments and computational studies were carried out to get an understanding of the flow field ... more Experiments and computational studies were carried out to get an understanding of the flow field around a rectangular supersonic intake with pointed cowl shape. Experiments include quantitative pressure measurements and flow visualization studies by using schlieren techniques. The effects of the presence of various cowl shapes on ramp surface have been obtained computationally at Mach 2.0. The experiments were carried out only for the pointed cowl. Schlieren Photographs were taken. Three-Dimensional simulations were made by using FLUENT at supersonic speed. The details of the experiments and computations are discussed.

Vibroengineering PROCEDIA, 2019

Fluid, non-stationary rigid body interaction is a commonly occurring phenomenon seen in many engi... more Fluid, non-stationary rigid body interaction is a commonly occurring phenomenon seen in many engineering practices. The article offers a new method using laws of classical mechanics for obtaining simplified analytical relations in analysis and optimisation tasks without using space time programming methods. In the proposed method the fluid space around the rigid body prisms is divided into two zones, pressure and suction (vacuum). The method is extensively discussed which is further extended for calculation of interaction forces and coefficients for non-stationary perforated plate with total area of perforations maintained at half the area of the complete flat plate. Experiments were performed for perforated plate in an Arm-field wind tunnel at constant speed of 10 m/s. The present work offers analysis and synthesis of specific engineering task of energy extraction from fluid in a unique way by making use of external fluid flow over a perforated plate. The fluid is assumed continuou...

Agronomy research, 2020

Autonomous under-water vehicles (AUV) performing a commanded task require to utilize on-board ene... more Autonomous under-water vehicles (AUV) performing a commanded task require to utilize on-board energy sources. At the time when on-board power source runs low during operation, the vehicle (AUV) is forced to abort the mission and to return to a charging station. The present work proposes the technique of an energy recovery from surrounding medium. This effect is studied for dual action actuator movement that obtains energy from fluid. It is realized that a flapping or vibrating actuator can be used for energy extraction phenomenon apart from the non-traditional propulsive technique. In the present work a simple dual flapping actuator that can switch between simple flat plate and perforated plate at extreme end positions (angles) by using an efficient mechatronic mechanism that would help in overcoming viscous forces of the operating medium is extensively studied. The main objective of the present article is to develop a new approach for energy gain and recharge power pack of on-board...

The aim of the paper is to analyze and optimize the operational safety and efficiency of wind ene... more The aim of the paper is to analyze and optimize the operational safety and efficiency of wind energy conversion equipment. A wind energy conversion device equipped with one oscillating flat blade has been developed and studied. In this device, lateral surface of the blade is firmly attached to the crank, which is kinematically connected with the generator’s slider moving inside the electric coil. As a result, electrical energy is produced in the linear generator. The considered electromechanical device is described by the second order differential equation. In this equation, the interaction of wind flow and relative motion of the blade is described by the approximate relationships of classical mechanics. Operation of the system due to the action of air flow is simulated with computer program Mathcad. Possibilities to obtain energy with generators of different characteristics, the operation of which is regulated by mechatronic control, have been studied. The effect of a constant wind...

The work is dedicated to the authors’ latest research on the interaction of moving inflexible obj... more The work is dedicated to the authors’ latest research on the interaction of moving inflexible objects when subjected to non-constant velocity fluid flow (air, water) without the use of work-intensive space-time programming methods. In the first part of the study, the differential equation of the plane pendulum motion is derived using the novel approach of fluid-rigid body interaction phenomenon, in this equation, the moment caused by the fluid interaction is simplified by ignoring the flow viscosity. This makes it possible to obtain the usual second-order differential equation of pendulum motion, which contains components of relative velocity in a simplified way, instead of the partial differential equations in a continuous mathematical space. The application of the obtained equation is further used in solving specific tasks of engineering importance. The first task analyzes the pendulum swing motion in a still airflow. Here, the equation described above is numerically integrated an...

Engineering for Rural Development

Fluid rigid body interaction is commonly occurring phenomenon and this phenomenon is of high impo... more Fluid rigid body interaction is commonly occurring phenomenon and this phenomenon is of high importance in many engineering applications. The main objective of the present paper is to analyse vibrations due to fluid-rigid body interactions by inclining the frontal area of flat plate to flow. As understood from the existing research, the main challenge is the understanding of non-stationary fluid body interactions. Interaction analysis, optimization and synthesis tasks include space-time programming methods and approximate analytical methods. This article discusses an approximate analytical method in which the object's interaction with fluid flow is divided into two parts in the fluid body interaction space. The first part is the frontal pressure side that arise as a result of change of momentum in the system that can be conveniently represented in a differential form. The second part includes the idea of describing the interaction behind the plate as a certain thin (vacuum) side was accepted. This thin vacuum side also depends on the frontal area flow interaction. The use and precision of the approximate analytical method was verified by experiments in the wind tunnel. The method was used for good analysing of varying frontal area (until flattening) of flat plate in fluid flow. The main parameters for motion excitation are the changes in plate-flow interaction area, velocity and angle of inclination of the flat square plate to the fluid flow. Experiments were performed at 10 m•s-1 keeping in view the wind speeds that were observed in the past in Riga, Latvia.

Fluid-rigid body interaction is an age-old phenomenon, but interestingly, a good approximated sol... more Fluid-rigid body interaction is an age-old phenomenon, but interestingly, a good approximated solution for the phenomenon pertaining to non-stationary body-fluid interaction is still non-existent. The solution is much more complicated due to huge system of simultaneous partial differential equations that are framed from multi-degrees of freedom, all elements in the spatial domain coupled together between all time steps. Additionally, when considering the spatial aspects of solving the system of partial differential equations, there arise a range of complexities from the type of solution technique (finite-differences, finite-volume, finite-element) and also from meshing techniques (moving, structured or unstructured). Even though advanced commercial fluid-structure interaction solvers are available, they are limited to simple objects and require frequent remeshing techniques that are time consuming and computationally expensive. The promotion work specifically focuses solely on rigid...

Lecture notes in mechanical engineering, 2021

Latvian Journal of Physics and Technical Sciences, Mar 30, 2021

21st International Scientific Conference Engineering for Rural Development Proceedings

19th International Scientific Conference Engineering for Rural Development Proceedings, 2020

World Journal of Engineering and Technology, 2018

Transport and Aerospace Engineering, 2017

Vibroengineering PROCEDIA, 2019

Agronomy research, 2020

Engineering for Rural Development