Department of Aeronautical Engineering (AE)

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A COMPARATIVE STUDY OF AERODYNAMIC CHARACTERISTICS OF NACA 0015 AND NACA 4415 AIRFOILS AT VARIOUS REYNOLDS NUMBER
(2023-02) MAZUMDER, MD.HASIB MAHMUD; CHOWDHURY, PAVEL; SHAHRIAR, SADIK
The shape of an airfoil is paramount to its aerodynamic characteristics. In many applications, the streamlined shape has proven to be the most effective geometry shape. Airfoils are employed in aircraft wings, tails, and other control surfaces, wind turbines, boats, and ships, among other things. The current study compares the numerical aerodynamic performance of two regularly used airfoils, NACA 0015 and NACA 4415. The study is to evaluate the performance of these airfoils in terms of lift, drag, and lift to drag ratio at various angles of attack using wind tunnel experiments and computational fluid dynamics (CFD) simulations. These two airfoils were evaluated in a subsonic wind tunnel at Reynolds numbers ranging from 1×105 to 3.5×105. The NACA 0015 and NACA 4415 were tested from 0° to 18° angle of attack with a 2° interval. The conventional Sparlat-Allamaras model is used in the computational procedure. The outcome demonstrates a similarity between experimental and CFD results. The lift and drag curves for both profiles follow the same pattern. The optimum angle of attack for both airfoils is 14 degrees. However, the experimental results show that drag is greater, particularly at higher angles of attack. Both airfoils are thick, which adds structural integrity to the blades at the expense of increased drag. Furthermore, it has been shown that symmetric airfoils offer no lift at 0° AOA, making them extremely useful in control surface applications, whereas cambered airfoils provide higher lift, which is beneficial for devices requiring more lift, such as wind turbines.
AERODYNAMIC ANALYSIS OF VARIABLE GEOMETRY RAKED WINGTIP
(2023-02) ISLAM, S M MOHAIMENUL; REZA, MD FOYZUL HAQUE; RAHMAN, MD HABIBUR
A computational and experimental analysis of a wing model with Variable Geometry Raked Wingtip (VGRWT) has been conducted to determine the aerodynamic performance advantages over an untreated wingtip. Computational fluid dynamics (CFD) simulations were performed to study the flow behaviour over the wing and the effect of changing the wingtip geometry on aerodynamic parameters such as lift, drag, and circulation. Wing models with raked wingtips at different angles of rake (250 , 300 , 400 , 500 ) and a baseline model with an untreated wingtip have been designed through Solidworks software. The designs are then imported to ANSYS (Fluent) software to carry out numerical investigation at different angles of attack (0 0 , 2 0 , 4 0 , 6 0 and 8 0 ). After that, the best-performing wing (Based on the simulation results) was fabricated and experimented with to validate the simulation results. All the simulations and experiments are conducted at a constant velocity of 20 m/s (0.0583 Mach). The results revealed that changing the geometry of the wingtip can have a profound impact on the aerodynamic performance of the aircraft. In particular, the study showed that raked wingtips could significantly enhance the lift-to-drag ratio, improving fuel efficiency and reducing emissions. The results of the CFD simulations also indicated that the angle of the rake plays a critical role in determining the aerodynamic performance of the raked wingtips. Optimizing the angle of the rake for specific flight conditions made it possible to achieve even more significant improvements in the lift-todrag ratio. Furthermore, the study found that the benefits of raked wingtips were particularly pronounced at high angles of attack and during takeoff and landing, where the improvement in lift and reduction in drag could have a substantial impact on the performance of the aircraft.
ANALYSIS OF FLOW DYNAMICS OF A NACA 2412 AIRFOIL WITH CAVITY THROUGH NUMERICAL SIMULATION AND WIND TUNNEL EXPERIMENT
(2023-02) NEWAZ, KAZI NAVID; CHOWDHURY AUNKUR, MD. SHAHRIA NEAJ; IBNE REJA TUR, MD. TAMZID
The paper presents the study of fluid flow analysis of NACA 2412 airfoil having cavities on its suction surface at different chord wise location from leading edge to trailing edge by numerical simulation and wind tunnel experiment. In this work, the behavior of a twodimensional model equipped with a span wise adjusted semicircular cavity positioned at 0.25C, 0.50C and 0.75C has been researched and compared with standard NACA 2412 airfoil. The two-dimensional airfoil models were created in SOLIDWORKS and mesh are created for numerical analysis using ANSYS Meshing, which is executed in Fluent for numerical iteration solution. The Spallart-Allmaras turbulence model has been used. From CFD-Post Coefficient of lift (Cl), Coefficient of drag (Cd) and lift to drag ratio, velocity streamline, velocity vector and coefficient of pressure along the chord length were monitored. Experimental tests have been performed on four wooden airfoil models at three different velocities. First the coefficient of lift (Cl), coefficient of drag (Cd) and lift to drag ratio readings were taken for the standard airfoil for different angles of attack varying the wind tunnel speed. Then the modified surface airfoil readings were taken at similar flow conditions. Adding cavity at 0.50C and 0.75C show higher lift coefficient values at all speeds. Drag coefficient increases with the increase of AoA and is minimum for airfoil with cavity at 0.50C. A delay of stall is seen for airfoils with cavity at 0.50C and 0.75C.
CHARACTERIZATION AND PREDICTIVE MODELING OF THERMALLY AGED GLASS FIBER REINFORCED PLASTIC COMPOSITES
(2023-07) RAHMAN, MD MIJANUR
This study investigated the characterization and predictive modeling of thermally aged Glass Fiber Reinforced Plastic (GFRP) Composites. The experimental part of the study explored the effect of fiber orientation, laser cutting and thermal aging on GFRP mechanical properties. The development of a predictive model for estimating the mechanical properties of thermally aged GFRP was explored in the computational part. GFRP composites were fabricated with woven and random glass fiber and epoxy resin hardener and subjected to mechanical and laser machining. Mechanical property testing reveals that Tensile and flexural properties are found to be superior in mechanically cut samples. Compromised surface integrity due to thermal damage in the case of laser cut samples is also noted. All results indicated that woven GFRP has superior mechanical properties than random GFRP. Woven GFRP tensile test samples were thermally aged at 50°C, 100°C, 150°C and 200°C for 30 mins, 60 mins, 90 mins and 120 mins. The samples showed a gradually increasing brown color at temperatures above 150°C. The tensile test showed that the Ultimate Tensile Strength (UTS) value had a general decreasing trend as the thermal aging temperature increased. The predictive model read the photographic image of a thermally aged sample and used the color change due to thermal aging as an identifier for the image processing algorithm. Artificial Neural Networks (ANN) estimated the thermal aging temperature and time from the image processing algorithm’s Red Green Blue (RGB) color matrix output. A regression equation was also developed which creates a mathematical relationship between the UTS values and the thermal aging variables from the experimental data. Finally, the ANN’s output was forwarded to the developed regression equation to get the estimated UTS. The predictive model’s estimated UTS showed an average accuracy of 97% compared to the experimental results. The results of the characterization of mechanical properties of thermally aged GFRP can contribute meaningful insights into the existing literature. The developed predictive model can have potential applications in aerospace line maintenance operations with the promise of cost and time savings.
CHARACTERIZATION AND PREDICTIVE MODELING OF THERMALLY AGED GLASS FIBER REINFORCED PLASTIC COMPOSITES
(DEPARTMENT OF AERONAUTICAL ENGINEERING, 2023-07) RAHMAN, MD MIJANUR
This study investigated the characterization and predictive modeling of thermally aged Glass Fiber Reinforced Plastic (GFRP) Composites. The experimental part of the study explored the effect of fiber orientation, laser cutting and thermal aging on GFRP mechanical properties. The development of a predictive model for estimating the mechanical properties of thermally aged GFRP was explored in the computational part. GFRP composites were fabricated with woven and random glass fiber and epoxy resin hardener and subjected to mechanical and laser machining. Mechanical property testing reveals that Tensile and flexural properties are found to be superior in mechanically cut samples. Compromised surface integrity due to thermal damage in the case of laser cut samples is also noted. All results indicated that woven GFRP has superior mechanical properties than random GFRP. Woven GFRP tensile test samples were thermally aged at 50°C, 100°C, 150°C and 200°C for 30 mins, 60 mins, 90 mins and 120 mins. The samples showed a gradually increasing brown color at temperatures above 150°C. The tensile test showed that the Ultimate Tensile Strength (UTS) value had a general decreasing trend as the thermal aging temperature increased. The predictive model read the photographic image of a thermally aged sample and used the color change due to thermal aging as an identifier for the image processing algorithm. Artificial Neural Networks (ANN) estimated the thermal aging temperature and time from the image processing algorithm’s Red Green Blue (RGB) color matrix output. A regression equation was also developed which creates a mathematical relationship between the UTS values and the thermal aging variables from the experimental data. Finally, the ANN’s output was forwarded to the developed regression equation to get the estimated UTS. The predictive model’s estimated UTS showed an average accuracy of 97% compared to the experimental results. The results of the characterization of mechanical properties of thermally aged GFRP can contribute meaningful insights into the existing literature. The developed predictive model can have potential applications in aerospace line maintenance operations with the promise of cost and time savings.
COMPARATIVE STUDY OF BLOWING AND SUCTION SLOT GEOMETRY OPTIMIZATION ON NACA 0015 AND NACA 2412 AIRFOIL
(2023-02) SHELA, SADIA SULTANA; FAISAL, SAMIA BINTA
Many investigations have been conducted to study the effect of boundary layer flow on the NACA airfoils. The studies are conducted to measure the lift and drag coefficients in accordance with different flow conditions. Additionally, the investigations focus on the leading edge blowing or suction and zero net mass flux synthetic jet impacts on vortex flow through airfoils. There are now suction and blowing techniques that have been investigated in several tests. These tests have shown that suction and blowing have the power to alter the pressure distribution over an airfoil surface and significantly alter lift and drag coefficients. The thesis entitled "Comparative Study of Blowing and Suction Slot Geometry Optimization on NACA 0015 and NACA 2412 Airfoil" aimed to analyze the effect of different blowing and suction slot geometries on the performance of NACA 0015 and NACA 2412 airfoils. The study used computational fluid dynamics (CFD) simulations to compare the lift and drag coefficients of the airfoils with different slot geometries. The results showed that optimization of the slot geometry can significantly improve the aerodynamic performance of the airfoils. The results of this study have important implications for the design of low-drag and high-lift airfoils for various applications, such as wind turbines and aircraft. The optimization of slot geometry is a cost-effective way to improve the aerodynamic performance of airfoils, and this research provides valuable insights for engineers and researchers in the field of fluid dynamics. The study also showed that the optimal slot geometry varied between the two airfoils and was dependent on the operating conditions. In conclusion, the thesis provides a comprehensive comparative study of the effect of blowing and suction slot geometry optimization on the performance of NACA 0015 and NACA 2412 airfoils. The study highlights the importance of slot geometry optimization for improving the aerodynamic performance of airfoils and provides valuable insights for engineers and researchers in the field of fluid dynamics.
DESIGN AND BUILD OF A SMALL FIXED WING UAV FOR SEARCH AND RESCUE APPLICATION
(2024-03) SYEED, FARHAN; HASNAYEEN, ASIF; IQBAL, MD. REDWAN; SHEIKH, MORSALIN
The entire design and development process of a small fixed-wing Unmanned Aerial Vehicle (UAV) made especially for Search and Rescue (SAR) missions is presented in this thesis. Because of its adaptability, agility, and capacity to reach difficult or isolated areas, unmanned aerial vehicle (UAV) technology has become a potentially useful instrument for improving search and rescue (SAR) operations in recent years. Nevertheless, the specialized elements required for successful SAR flights are frequently absent from current commercial UAVs such as telemetry, radio transmitters etc. The primary objective of this research is to bridge this gap by designing and building a custom UAV optimized for SAR applications. The design process involves a systematic approach encompassing aerodynamic analysis, structural design, payload integration. Furthermore, the integration of sensors, including GPS and cameras, enables the UAV to effectively detect and locate individuals or objects in challenging terrain and environmental conditions. To ensure that the planned UAV prototype performs well and is reliable for real-world applications, it is put through testing and assessment in our MIST field.
DESIGN AND DEVELOPMENT OF MFD PAGES FOR FIGHTER AIRCRAFT USING FLIGHTGEAR FLIGHT SIMULATOR DATA OUTPUT
(2024-02) TOWFIQUE, SYEDA TASNOVA; ERSHAD INAN, NAFIM; APEE, MARIA ZAMAN
Modern fighter aircraft are equipped with various sensors which provide a considerable amount of information to the aircrew. These sensors send data to various systems via the avionics data bus. This data is processed by the Display Processor and utilized by the Multi-Functional Displays or MFDs to present the information in a form that helps the pilot to easily process the information and help him to accomplish the mission. The Multi Functional Display or MFD is a type of electronic display system used in aircraft to process and present critical information. This study presents a typical Multi-Functional Display (MFD) that combines fundamental functions that can be processed and presented to the aircrew in the form of various pages to provide a precise, informative, and personalized flight display. It differs from a standard display since it can handle several applications on a single piece of hardware. The earlier aircraft cockpits were equipped with various analog instruments and gauges. However, in the present generation of aircraft, they are replaced by modern glass cockpits. Flight data and information required for an aircraft are now displayed in a single integrated screen, which is the MFD. Fighter aircraft pilots depend on MFDs to get vital information regarding the aircraft's flight condition, system health, and current mission status. MFD page design and development is a challenging process that necessitates giving careful thought to the demands of the pilot and the information that matters most to them in each particular scenario. The key functions of the MFD have been defined in various pages such as Primary Flight Display (PFD), System operation, and Navigation page. In our study, the FlightGear Flight simulator was used to provide real-time flight data for developing the MFD System. Since it is not possible to obtain the data from a real aircraft for now. Therefore, the Flightgear property tree was effectively used for the Design, Development, and for testing of the pages. As a future scope, real-time data from a drone or a UAV or even data from an actual aircraft can be used to run the MFD pages.
DEVELOPMENT AND TESTING OF A LOW POWERED COST-EFFECTIVE FREQUENCY MODULATOR FOR APPLICATIONS IN RF TRANSMISSION
(2023-02) ISHRAT JAHAN, TASNEEM; HOSSAIN, MD MUZAHID; NAHIAN, DEWAN SHEGUFTA
In this thesis the frequency modulation for different types of modulating circuits was studied and a low-powered, cost-effective modulator was developed. By changing the wave's instantaneous frequency, information is encoded in a carrier wave using frequency modulation. The technology is utilized in computing, signal processing, radio broadcasting, navigation and telecommunications. Three modulating circuits were designed and developed for the study. The performance of Triangular Modulating Circuit, Sawtooth Modulating Circuit and Sinusoidal Modulating Circuit was studied and analyzed in terms of message transmission. To validate the proposed modulating circuit, its performance was compared with MATLAB script, Simulink model and Python script. Its performance was also compared with the modulation done by existing model “EMONA Telecoms- Trainer 101” present at Electrical, Electronic and Communication Engineering lab of MIST. Results of the analysis show that if the modulation is linear, the frequency change is directly proportional to the modulating voltage's amplitude. Parameters of the modulated signal when used in MATLAB, Python and Simulink gave the same modulated signals that validates the modulation done by the proposed circuits. The proposed modulating circuits generate signal with very less noise at the desired voltage level which also matches the performance capacity of microwave VCOs. And so, it can be used effectively to develop a low cost FMCW Radar. The proposed modulating circuits can be used in telemetry, video broadcasting and recording, sound synthesis, medicine, navigation, aviation, radar, analog and digital data transmission and many other fields to a further extent
DEVELOPMENT OF AL-BASED METAL MATRIX COMPOSITES REINFORCED WITH HYBRID NANO PARTICLES AND ITS MACHINABILITY TEST
(2024-09) KABIR NAYEEM, MUHAMMED HASNAIN
Aluminum is a significant material for all type of manufacturing industries due to its wide range of alloys and composites. Despite the fact that aluminum alloys have been used in a wide range of industries due to their excellent and diverse functional characteristics, composite materials can be modified to provide specific mechanical and tribological properties. An aluminum alloy with lesser hardness and tensile strength has been strengthened dramatically by adding ceramic reinforcements. This study aims at formulate and develop hybrid particle reinforced Al-metal matrix composites using stir casting method, a novel fabrication process in our country to fabricate metal matrix composite. Also, followed by investigation of its the physical, mechanical, morphological and machinability characteristics of the developed metal matrix composites. Three unique compositions of composites have been obtained by varying the wt. % amount of carbon nanotube, alumina and silicon carbide particulate reinforcements respectively 1%, 2.5% and 2.5%. Various mechanical properties, essentially the tensile strength, flexural strength, hardness, impact resistance; and physical properties like porosity, and density were tested; and a morphological and machinability study has been carried out for investigating the performance of the newly developed composites. The study showed that there was an 128.57% increment of tensile strength, an 7.1349% increment of hardness, an 45% increment of impact resistance, and a 0.8301% reduction of density by adding the particulate reinforcements in aluminum metal matrix composite. The morphological analysis demonstrated a more homogenous dispersion of reinforcement particles in the composite, which indicated the effectiveness of the stir-casting fabrication method. From the optimized machining parameters, it was evident that higher cutting speed and feed rate can be obtained by introducing multiple particulate reinforcement in the metal matrix, which eventually increased the productivity, efficiency and product quality of the developed composites.
DEVELOPMENT OF EPOXY COMPOSITES REINFORCED WITH CARBON NANOTUBE AND NATURAL FIBER FOR COMMERCIAL APPLICATIONS
(2023-09) BHADRA, DEBANAN
The global economy has gone through significant alterations in recent years, particularly after Covid-19 epidemic, with an increasing importance on biodegradability, resource effieacy, as well as environmental responsibility. Keeping that in mind, this study focuses on developing composite materials with Epoxy resin as matrix material, natural fibers as reinforcements and Multi-Walled Carbon Nanotubes (MWCNT) as nanofiller. This present study is intended to develop natural fiber and MWCNT reinforced epoxy composites with a view to investigate their physical and mechanical properties, as well as to model the mechanical properties using Finite Element Method (FEM). However, as there are lot of different natural fibers with varying mechanical properties, this study has employed a fuzzy Multi Criteria Decision Making method to select the best natural fibers among twelve alternatives and found that the pineapple fiber and coir fiber are the top two candidates among different fibers. Therefore, this study used pineapple, coir, and sisal fiber as natural fiber reinforcements. Alkali treatment using sodium hydroxide (NaOH) was employed for surface modification of natural fibers, enhancing their compatibility with the epoxy matrix. Moreover, ultrasonication technique was used for achieving uniform dispersion of CNTs within the epoxy matrix. Different physieal properties such as, density, void contents, and water absorption, as well as some mechanical properties such as tensile strength, Young's modulus, elongation at break, flexural strength, flexural modulus, Rockwell hardness number and impact energy were measured. Fourier Transform InfraRed (FTIR) spectroscopy was earried out to observe the change of molecular structure of the composites because of the interaction among epoxy, natural fibers and MWCNT. Scanning Electron Microscopic (SEM) images were analyzed to understand the microstructure of the composites. Furthermore, Microstructure-Free Finite Element Model (MF-FEM) was applied to simulate the mechanical behavior of the composites. Findings from the study showed satisfactory improvement in most of the physical and mechanical properties with addition of MWCNT up to a certain extent. However, addition of CNT resulted in increased density and brittleness of the composites.
DEVELOPMENT OF HANDLING QUALITIES SIMULATOR USING MATLAB, SIMULINK AND FLIGHTGEAR
(2024-03) JAZUAAN, AHMED; MOHIM, MD KHAIRUL ALAM; MORSHED, RIZWAN
The Handling Qualities (HQ) Simulator is a software developed to study the Handling Qualities of a Fixed Wing aircraft based on the aerodynamic coefficients and flight conditions. This software would indicate if the aircraft would be stable, unstable or neutrally stable under these conditions. In this HQ Simulator, one can input the vital aerodynamic coefficients of a newly designed aircraft (or an existing aircraft) and the software will indicate if the aircraft is going to be stable or unstable depending on specific pilot input. HQ Simulator has two main parts, first part calculates Longitudinal handling qualities and the second part calculates Lateral & Directional handling qualities. The longitudinal handling qualities part of the simulator shows the change of angle of attack, pitch rate and pitch angle in real time and the lateral & directional handling qualities part of the simulator shows change of sideslip angle, roll rate and yaw rate in real time. Additionally, the software is designed to display a simulation of that aircraft using an open source flight simulator called FlightGear. Presently, three standard types of simulated pilot inputs can be given to the aircraft using the software, namely Doublet, Pulse and Step input. The amplitude, duration and starting time of the inputs can also be specified by the user. For this study, the aerodynamic coefficients of General Dynamics F16 Fighting Falcon are given as default in the simulator. The user can change the aircraft parameters easily. The user can also select other aircraft using a dropdown menu. To validate the results of the Handling Qualities simulator, another software was developed which takes the governing 6DOF (Six Degrees of Freedom) Longitudinal and Lateral-Directional equations of motion and calculates the modal parameters of the response. This will greatly help the user to classify the type of the aircraft and the level of flying effort required with respect to the Handling Qualities Rating (HQR) given by using Cooper Harper Scale. Designers of Auto stabilizers, Autopilots and Fly by Wire systems can use this simulator to study the effect of their systems before they are installed on the aircraft. Thereby helping in saving crucial man-hours, flight test effort and human life.
DEVELOPMENT OF MORTAR FIRING SIMULATOR FOR TRAINING AND PREDICTING THE ACCURACY OF ITS PROJECTILE
(2023-02) TASNIM, SARAF; APSHARA, NOOR-E-JAMILA
At present, one of the most vital weapons of Bangladesh Army is the mortar. For facilitating the mortar training of the troops, in this thesis paper we have reflected a method for predicting the accuracy of unguided mortar shells. The aim was to develop a process that would estimate accuracy with lesser effort avoiding the use of a large database. In this method, we have used the Zero Drag Model and Air drag model to predict the error which will facilitate in giving corrections easily. Different formulas are used to calculate the range and maximum altitude of the trajectory of the projectile. The developed program is coded in MATLAB and the results can be easily computed in less than 30 seconds for most ranges. A Graphic User Interface uses a combination of technologies and devices to provide a platform that users can interact with, for the tasks of gathering and producing information. In our paper we have used GUI is used to visualize the coded program. The program was verified by comparing it with the Firing Table of 82 MM MOR TYPE PP87 (NEW AMMO). The mortar crew will put the desired input according to the target placed on the screen. Users will be able to see the impact point and also the deviated information in terms of range and azimuth. The model is not able to take into account wind effects and varying levels of meteorological data staleness. The developed program can be used to predict accuracies for any unguided projectile given the required data. Finally the automatic firing solution generator for mortar crew will be created by developing a mortar simulator where the crew can practice firing after following the correct procedure.
EVALUATION OF STABILITY & PERFORMANCE ANALYSIS WITH MODIFICATION & OPTIMIZATION OF DESIGN OF A FIXED WING TARGET DRONE(UAV) FOR AIR DEFENSE SYSTEM
(2023-02) JEWEL, NAZMUL HASAN; NILOY, MD NAIMUL ISLAM; RAHMAN, MD SOHANUR
The objective of this study was to assess the fly worthiness of a designed target UAV. Initially, the aircraft was found to be statically longitudinally unstable, but modifications and optimizations were made to improve its stability. The semi-empirical formulas were used to calculate the moment contributions of the various components of the unmanned air vehicle, and the results were visualized through a graph displaying the overall effect of all components. A detailed SolidWorks model was created to gather the necessary information for the calculation, and the relevant geometric and aerodynamic properties for longitudinal, lateral, and directional stability were determined for both static and dynamic scenarios. The approximate model of the UAV was created using XFLR5 software, from which the necessary graphs and values were obtained. The values obtained from the semi-empirical formulas and XFLR5 were compared to validate the results. The final analysis was conducted to ensure the fly worthiness of the designed UAV. As a result, the optimized model was found statically stable where the moment coefficients were 𝐶𝑚𝛼 < 0 , 𝐶𝑛𝛽 > 0 & 𝐶𝑙𝛽 < 0 . In the dynamic stability part, all parameters were found to be stable except for the spiral mode. The performance parameters were also calculated for different altitudes and compared with XFLR5 parameters and the results were satisfactory.
EXPERIMENTAL INVESTIGATION OF ELECTROMAGNETIC BEHAVIOR OF ALUMINA REINFORCED COPPER MATRIX COMPOSITES
(2024-02) ISLAM, TARIQUL
Copper is the third highest used metal in the industry because of its excellent electrical conductivity (100% IACS) with relatively high hardness at room temperature. However, the continuous degradation of mechanical performance of pure copper with increasing temperature eventually limits its use for electronic construction, especially for high temperature applications. Moreover, due to the conventional theoretical assumption of electromagnetic properties of metallic copper, scientists hardly made attempts to reveal the potential applicability of copper for next generation technology. In this research, attempts have been made to overcome the high temperature degradation of pure copper using trace addition of nano-crystalline Al2O3 particle as well as to evaluate the corresponding electromagnetic performance of copper. 99.99% pure copper was subjected to reinforcement using 0.5%, 1%, 2% and 5% white Al2O3 particles through conventional sand stir casting technique. The little percentage of Al2O3 made significant impact on the mechanical and electromagnetic properties of copper, especially when subjected to thermal treatments. The microhardness of Cu-Al2O3 composite increased with the increase of annealing temperature up to 6000C according to Hall Petch theory. The electrical conductivity was found to be very close to that of copper observed at room-temperature condition. The diamagnetic behavior of copper was transformed to paramagnetic behavior with the trace addition of Al2O3 particles, which was further influenced significantly by the thermal treatments. Dielectric behavior of pure copper was also investigated and the result of which were justified using Jonscher’s theory of colossal permittivity. The present investigation suggested that the proper selection of composition and appropriate post thermal treatment can improve the mechanical as well as electromagnetic property of Cu-Al2O3 composite, thereby revealing the potential applicability of copper for future high-temperature/power applications.
EXPERIMENTAL STUDY OF AERODYNAMIC COEFFICIENTS, CO-EFFICIENT OF PRESSURE AND FLOW-FIELD AROUND NACA 0012 AIRFOIL
(2023-02) ISLAM, RIFAH TAMANNA; TAHMID, PRIYAM IFTIKHAR; IBNE ZAKIR, ZABIR
In this thesis, the result of experimental study of aerodynamic coefficients, CL, CD, Cm, coefficients of pressure, CP, and flowfield around NACA 0012 airfoil has been described. An open loop subsonic wind tunnel, AF100, was used to conduct the experiment for two reynolds number 10.15 104 and 15.23 104 and with different angle of attack- 0 degree, 5 degree, 10 degree, 15 degree, 20 degree. Pitot tube was used to measure the flow velocity. Again yawmeter was used to collect and calculated data of flow angularity around airfoil. The data of lift, drag and pitching moment were collected from VDAS for calculating CL, CD and Cm. Pressure coefficients Cp were calculated from the pressure readings of 20 pressure tappings around the midplane of the airfoil. The result shows that no lift is generated at 0 degree AOA, but with the increase of AOA, significant amount of lift and drag is generated. Vortex was found to occur at the trailing edge due to flow separartion. The result shows that with the increasing AOA, flow separation region is getting increased. For greater reynolds number, the phenomena is more prominent.
EXPERIMENTAL STUDY OF FLOW AROUND A ROTATING CYLINDER
(2024-03) MOON, MITHILA ISLAM; SHABNAM, HASSAN MAYESHA; MOHSINA AKHTER, SYEDA
Experimental measurements were made of the flow field surrounding both stationary and rotating cylinder at various Reynolds numbers depending on the velocity changes. The investigation concentrated on the distribution of turbulence of fluid flow and velocity at different distances behind the rotating cylinder. The following results were reached after comparing with the theoretical model using numerical simulations to investigate fluctuations in the flow field: The velocity mutation position below the wake region moves upward as the cylinder rotates counterclockwise, but the position above stays the same due to an increase in relative speed (at the same Reynolds number). Furthermore, the velocity mutation position beneath the wake region shifts somewhat downward with increasing Reynolds numbers. Based on numerical simulations, lift force is affected by a substantial upward movement of the bottom vortex position behind the cylinder following the rotational speed. Changes in the lower vortex position have an impact on the wake region's free shear layer and lift force, especially at high Reynolds numbers.
EXPERIMENTAL STUDY OF FLOW VELOCITY AND DIRECTION AROUND NACA 0012 AND NACA 0015 AIRFOIL
(2022-03) RAHMAN, MD MAHFUJUR; MAIESHA, JAHURA JANNAT; MARMA, UKYAWSAIN
In this thesis the result of experimental study of flow velocity and direction around NACA 0012 and NACA 0015 airfoil has been described. A closed loop wind tunnel was used to conduct the experiment with a constant flow velocity of 15 m/s and different Angle of Attack- 0 degree, 5 degree, 10 degree, 15 degree. Pitot tube was used to measure the upstream velocity. Again yaw meter was used to collect and calculated data of flow velocity and direction around airfoil. The reverse flow was found to occur at the trailing edge of the airfoil. The results shows that if a constant flow velocity applies at two different symmetrical airfoils of similar chord and similar AOA, the airfoil which have more thickness than other one can cause more reverse flow at trailing edge. So thin airfoils are more suitable than thick airfoils.
EXPERIMENTAL STUDY OF MEAN FLOW CHARACTERISTICS OF SWIRLING JETS
(2023-02) TASFEE, NAFISA IBNAT; HASAN, SM MEHADY; RUDRO, MD. SOYKOT TANVIN
Different characteristics and performance parameters for the exhaust of nozzle are analyzed both experimentally and analytically to observe the behavior of the free jet and swirling jet discharge into a quiescent environment. Swirl plays a significant role by escalating the dispersion of free turbulent jets. Swirling jets represent one of a few basic flow pattern that has a great practical significance in practical field. It allow the fundamental study of complex but generic dynamical processes and their interactions. They feature prominently in a variety of propulsion systems. In combustion application, their ability to create reverse flow regions near the jet nozzle has been exploited for the purpose of swirl-stabilizing the flame. Swirling jets have many other possible industrial application also. The objectives of the present research is a comparative study between the plane circular jet and swirling jet. It was carried out to assess the effect of initial condition such as Reynolds number and pitch of swirls generator on swirling jets. A circular nozzle of 60 mm diameter was used for the whole experiment. Velocity profiles were attained for two initial condition Re = 8.4e4 & Re = 1.27e5. In the measurement system a 3-hole yaw-meter of United Sensor Ltd (USA) along with sensitive incline tube manometers were used for the measurement of axial velocity and flow direction. The yaw-meter was located in different position of the jet flow by a precision height gause which was mounted on a precision traversing mechanism. The velocity profiles for six conditions (a) Free jet, (b) Free jet with extension tube, (c) Swirling jet using 5 deg. (d) Swirling jet using 15 deg.. (e) Swirling jet using 15 deg. were evaluated in this study. It was found that the Reynolds number had little effect on the velocity profile of any of the described six cases. A top hat shaped velocity profile was observed near the nozzle exit of plane jet, as the flow develops the shape changes and become more like inverted U shape. The velocity profile for the free jet with extension tube is quite similar to the free jet but the profiles were smoother. Introduction of swirl with the jet increases the mixing of jet with surrounding air. For swirling jet the velocity deterioration is quicker than free jet. The potential core of free jet was present up-to axial distance of X/D = 3.5.
EXPERIMENTAL STUDY OF THE FLOW FIELD OF AN ANNULAR JET COALESCING AT THE EXIT
(2023-03) DAS, SUDIPTO TUSHAR; KHAN, SAIKAT; KOWSHIK, ISHTIAK AHMED
An experimental investigation has been carried out to analyze the jet development and performance characteristics issuing from different configurations of annular nozzles at Re = 4e4, 8.4e4, and 1.2e5. Yaw-meter pressure measurements were carried out along the jet centerline for various vertical distances to quantify the potential core and characteristic decay of the jets. Flow visualization was performed by vector plotting to analyze jet structure at different cross-sections along the jet axis, which was used to study the behaviour of the flow development. The flow features reveal that the axisymmetric annular structure of the jet results in enhanced mixing of the jet. It is also evident from the yaw meter measurement that the jet spread is 50% and 20% lower than Re = 1.2e5 for Re = 4e4 and 8.4e4, respectively. For a particular Reynolds number, in most of the cases, the spread rate in an annular jet was decreased. Overall, the magnitude of centerline velocity in annular jets has also decreased. Furthermore, the existence of a potential core is found in free jet only.