Department of Aeronautical Engineering (AE)

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PREDICTION OF ICE ACCRETION AND CFD ANALYSIS OF NACA 2412 AIRFOIL FOR EVALUATION OF AERODYNAMIC PERFORMANCE DEGRADATION
(DEPARTMENT OF AERONAUTICAL ENGINEERING, 2019-08) FERDOUS, MAHBUBA
High altitude flights possess significant icing hazard in certain type of atmospheric conditions. This ice accretion on aircraft wing leading edges and engine nacelle pose threat to the flight safety. From early days of beginning of high altitude flights, numerous studies have been undertaken to determine the effects of icing on aircraft performance. Bangladesh is now moving at galloping pace in the aviation industry, and is expected to take leap of high altitude flight designs in near term period. This could be accomplished if several technologies are developed in-house prior to design and development of high altitude flights. One such requirement is the development of code for prediction of ice accretion and subsequently to design the anti-icing system. With this long term goal in mind, the present research focuses on understanding of the analytical approaches to predict ice accretion physics on aircraft wing cross section. Using the existing ice accretion thermodynamic and other conservation laws presented in open literature, a computer code was developed to predict the ice accretion over the airfoil. The code developed was validated against the experimental ice shapes from the open literatures. Using the developed code, the ice accretion prediction is undertaken on a specific airfoil i.e. NACA 2412, a most common airfoil cross section for moderately high altitude flights. The aerodynamic performance of the predicted ice accretion was analyzed using the Computational Fluid Dynamic (CFD) technique. The aerodynamic study was undertaken for three different icing conditions and it suggests that the ice accreted airfoil possesses lower lift than the base airfoil. It is also observed that the increase in the drag for ice accreted airfoil is significant as compared to base airfoil. Results of the study show that, most critical and worst icing occurs in presence of altocumulus clouds forming mixed ice on the airfoil leading edges. Such icing conditions result in reduction in lift coefficient and increase in drag coefficient approximately by 90% and 800% respectively compared to the base airfoil. These observations are in consonance with the published literature available in open domain. The current research is considered as the stepping stone for subsequent development and improvement of icing codes as well as design of anti-icing systems.
STUDY OF MULTISPECIES NANO-PARTICLES TO ENHANCE THERMO-HYDRAULIC PERFORMANCE IN MICROCHANNELS
(DEPARTMENT OF AERONAUTICAL ENGINEERING, 2019-08) RASHID, MOHSINA
Nanofluid is the colloidal suspension of nano-sized solid particles of metals or metal oxides in base fluids such as water, ethylene glycol etc. When liquid is mixed with nanoparticles, it exhibits substantially higher thermal conductivity than those of the corresponding base fluids. The augmented thermal conductivity of nanofluids over the base fluids is considered one of the driving factors for enhanced heat transfer performance of nano-fluids. The forced convection heat transfer of nanofluid is investigated by numerous researchers over the last few years. Recently, multispecies nanofluids have been defined as a new class of nanofluids with possible applications in almost all fields of heat transfer. The idea of using multispecies nano-fluids is expected to improve the heat transfer characteristics of individual nanofluids and to beneficially combine different properties from metal oxides, metals etc. The present research work is undertaken using the Computational Fluid Dynamics (CFD) to analysis and assess the high performing nanofluid for micro-channel applications. The study considers three metal oxide, two metal nano particles and their combinations in the base fluid i.e. desalinated water. The study is conducted for different Reynolds numbers and heat capacity. The performance of the nano-fluids is assessed based on the convective heat transfer coefficient, Nusselt number and pumping power requirement based on total pressure loss. The extensive numerical analysis suggests that MgO-Water nano-fluid possesses excellent heat transfer performance over other combinations considered. Study also reveals that the metal oxides possess better cooling performance in terms of convective heat transfer coefficient as compared to metal nanofluids. Among multispecies nanofluids of Ag-MgO-Water, Al2O3-Cu-Water and CuO-Cu-Water, the Al2O3-Cu-Water nano fluid performed better providing highest Nusselt number which is approximately 6% over and above that provided by pure water. Utilizing the data generated by parametric study for different nano-fluids, two combinations nanofluids are utilized for design of a compact heat exchanger with three different heat capacities i.e. 1 kW, 50kW and 100 kW. The hydraulic performance of this heat exchanger was compared in terms of pumping power requirements and it revealed that pumping power requirement increases nearly exponentially for higher 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.
SHAPE OPTIMIZATION OF GURNEY FLAP ON AIRFOIL
(2022-03) CHOWDHURY, AFSARA ZAHIN; MORSHED BHUIYAN, H.M. MONJUR; RAHMAN, MAHATHIR
Gurney Flap is known as a special type of high lift device that can help to change the performance output of an airfoil very beautifully. The first and foremost advantage of using Gurney Flaps is that these flaps are used so that most importantly lift force can be increased along with a moderate decrease of drag force under certain lift conditions for a given lift coefficient. Initially Gurney Flap was applied only to Automobiles, especially in race cars. Recently this flap is being tried to be applied to airfoils, wind turbines, rotorcrafts too, which is in research process. Gurney Flaps have been widely studied and applied in airfoil dynamic as well as static stall control, ground effects, flutter control, flapping airfoil control and rotor blade load control. Many researches from different countries have been conducted on the mechanisms of Gurney flaps using numerical simulations and wind tunnel tests. Our main concern of this thesis is to observe and understand the effect of this Gurney flap on airfoil and analyze its effectiveness. Overall 65-70 research papers have been scrutinized for our research to understand the basic concept of this flap and its applications. Different angles of Gurney flap with the chord have been experimented in this research to determine its effect on airfoils Lift, Drag, Pitching moment for both laminar and turbulent flow. Experimental approach using Wind tunnel have been followed for subsonic flows in this case.
STUDY AND DEVELOPMENT OF MOVING TARGET LOCATION AND RANGE ACQUIRING SYSTEM ALONG WITH GUI TO INCORPORATE IN A PROTOTYPE LOW-COST ACTIVE PHASED ARRAY RADAR.
(2022-03) AKASH, MD. ZAHIRUL ISLAM; IQBAL, S.M. SHAHRIAR
Radar is a detection device that employs radio waves to assess an object's distance, angle, or velocity. A Radar system comprises a transmitter that generates electromagnetic waves in the radio or microwave frequency range, a transmitting antenna, a receiving antenna, and a receiver and processor that determines the object's attributes. The object reflects radio waves from the transmitter, which return to the receiver and provide information on the object's location and speed. A phased array Radar usually means an electronically scanned array Radar, a computer-controlled array of antennas that creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas. The proposed research will provide the necessary knowledge of the cost-effective phased array Radar transmission system’s moving target location and range acquiring progress, including examining all the major subsystems via antenna principles and operation and software algorithms and simulations for search detection. The thesis was carried out to extract raw data from Infineon Technology’s Radar demo board Position2go based on the BGT24MTR12 transceiver and XMC4700 32-bit ARM® Cortex®-M4 MCU series. Using the built-in GUI of the Position2go module, raw data extraction was impossible. The system firmware was only compatible with a built-in GUI. Upon extracting the MATLAB code of the Position2go module, the IQ domain raw data could be extracted and plotted to visualise the graphical representation. From the graphical representation of IQ raw data, it was found that the graphical curve varies with the distance, angle & shape and as well as with the Approaching and Departing of the target. So with the help of this IQ raw data processed into the frequency domain and applying FFT, the distance could be measured, and by using phased FFT, the velocity could be achieved of the target, and also this raw data varies with the Departing and Approaching of the target and as well as with azimuth change. These possibilities can be distinctively identified and analysed through the graphical representation where different curve comparisons exist. The comparison ultimately leads towards the information given by the built-in GUI. And by doing extensive research on these IQ raw data of different possibilities of the target, a further developed private made GUI can be designed with the future development of this low-cost Position2go Radar module.
FLOW CHARACTERISTICS AND HEAT TRANSFER CHARACTERISTICS OVER NACA 4415 AIRFOIL
(2023-02) ALAM, FAIAZ UL; BAYZED, MD.FAYSAL MAHAMUD; ISLAM, MD.REDOANUL
NACA 4415 is the most common four-digit unsymmetrical aerodynamic shape. There are various applications of this airfoil in our day-to-day life and the aerodynamic sector, mostly in the design of fighter aircraft. The flow characteristics and heat transfer characteristics of the NACA 4415 airfoil are investigated by flow simulation and heat transfer using the computational method with the help of CFD in Ansys workbench and experimental analysis as the airfoil approaches the upper surface of the wind tunnel. The experiments were performed at Reynold’s Number of 2.5* 105 and different height ratios with various angles of attack. The specific Reynold’s Number was chosen to ensure that the flow generated is of turbulent type. The results that were obtained from the experiment are shown in terms of pressure coefficient, drag coefficient, and Nusselt’s Number for the different height ratios and different angle of attack. This work is one part of the extensive and general investigation that is being carried out. The results of the experiment are found in the above terms as the height ratio decreases and the negative pressure coefficient decreases. In the case of the heat transfer computation, we have seen that Nusselt’s number decreases as the decrease of height ratio.
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.
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.
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
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.
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.
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.
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.
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.
VOICE (GENDER) DETECTION FROM SUPERVISED LEARNING ALGORITHM USING MFCC IN BENGALI LANGUAGE
(2023-02) Rabsha, Halima Akther; Ferdous, Jannatul; Shanto, Md Mohiuddin
Gender detection from human behavior is a complex problem for digital technology studies. A collection of methods has been used to identify pertinent elements that can be used to create a model from a training set to classify gender from a voice signal. In this study, the Mel Frequency Cepstral Coefficient was used to distinguish between male and female voices in Bengali. 120 data of different voices were taken in wave (.wav) format and the audio length was five seconds for each data. For digitalized data, feature extraction was done by MFCC. After that, Singular Value Decomposition (SVD) was done to decompose the data into a single row with 14 coefficients. The extracted features are then used to train a supervised learning algorithm, such as a Support Vector Machine (SVM), with 86.7% accuracy for our train data set, to classify the gender of the speaker. The App Designer tool, Matlab GUI provides a userfriendly interface for users to input speech signals and display the predicted gender. The results show that the proposed model achieves high accuracy in gender detection on the test data set, real-life data has an accuracy of 83.33% for male voice prediction, and recorded data has an accuracy of 90%. Real-life statistics on women are 80% accurate, while recorded data are 86.67% accurate.
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.
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.
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.
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.