bluuebunny/crossref_metadata_2025 huggingface dataset:
Multifunctional Structure Calibration by Optimal Measurement Using Hybrid Approach for Response Monitoring
Authors: C.N. Sathyanarayana  , S. Raja
Published: December 2023

Multifunctional structure calibration by optimal measurement using hybrid approach is developed for the conventional strain gauges for response monitoring. In the hybrid calibration approach, we have used the finite element analysis and experimental modal technique to quantify the measured output of distributed sensors. Smart materials such as piezoelectric (PZT and PVDF) in thin film form are widely appreciated for distributed sensing application in composite structures. The light weight composite structures can be made multi-functional by incorporating the piezoelectric materials to have non-structural functionalities such as sensing, actuation, energy harvesting and health monitoring. In the present study, in addition to load carrying and damping, which are the essential structural functions, the composite plate is made to have self sensing capability with four distributed strain gauges and PZT patches respectively. Further, it has been shown that using a single strain measurement, the finite element strains can be updated at different assumed strain gauge locations in order to calibrate the PZT patch sensors placed nearby to output engineering strains.
Parametric Trend Study During Stability Analysis of a Tethered Aerostat
Authors: Rakesh Kumar  , Shashank Srivastava  , A.K. Ghosh  , Balraj Gupta  , Ajit Kumar
Published: December 2023

The paper presents the longitudinal and lateral stability analysis of an aerostat tethered in a steady wind. The parametric trend study showing the effect of variation of different parameters on longitudinal stability boundaries of an aerostat has also been presented. In contrast with the conventional airplane, the equations of motion for the tethered aerostat included buoyancy forces, apparent mass terms and static forces resulting from the tether cable. The analysis consisted of mathematical modeling and its use to compute the stability characteristics for the longitudinal and lateral cases followed by the parametric trend study carried out by varying the dimensional, aerodynamic and other parameters of the aerostat for the longitudinal case. Graphical results show that the aerostat is stable for longitudinal as well as lateral case. The parametric trend study presented, thereafter, suggested that the judicious and feasible choice of various aerostat parameters could be utilized to design a new aerostat that can remain stable for wide range of wind velocities.
Life Analysis of TBC on an Aero Engine Combustor Based On In-Service Failures Data
Authors: R. Raghupathy  , R.K. Mishra  , R.D. Misal
Published: December 2023

TBC (Thermal Barrier Coatings) mostly find application in the combustion sections of aircraft turbine engines. With the demand for fuel economy and increased power, combustion temperatures are approaching the design limits of the metal alloys from which hot end components are made. Modern TBCs are required to not only limit heat transfer through the coating but to also protect engine components from oxidation and hot corrosion. When a TBC fails, it exposes the underlying substrate to very high gas temperatures and the life of the component gets reduce drastically. With a failed TBC, a component can even fail within its prescribed service life. This is an airworthiness issue. So it is essential to estimate the TBC life accurate possibly to ensure airworthiness of the aircraft at any given time. Premature failure are observed in the TBC applied over combustion section of a turboprop engine. The engine is 800 shp class and it powers a commuter aircraft. The objective of this paper is to find out mean life of the coating by life data analysis. The data has been fitted to Weibull distribution. The Weibull parameters have been discussed which highlights the dominating cause for TBC failure and hence suggestion for life improvement of TBC system has also been made. The need for TBC system redesign has been emphasized. In addition to this, it also presents a comparison between different users/ operators.
Ionospheric Effect on Global Navigation Satellite System Performance - A Review
Authors: Sujan Kumar Saraswati
Published: December 2023

Satellite-based Communication, Navigation, Surveillance and Air Traffic Management (CNS/ATM) systems have been adopted by the international aviation community to meet the challenges of continuously rising global air traffic. Global Navigation Satellite System (GNSS) has been prescribed for the provision of navigation services to the air traffic. Performance of GNSS depends upon many factors including refraction and scintillation effects of ionosphere on the satellite signals. Severity of this effect depends largely upon the geographical location of the navigation receiver, the time of the day, the month of the year and the year on the 11-year solar cycle. This paper studies ionosphere mechanism and discusses its effect on the performance of GNSS. The paper also predicts the performance during solar cycle maximum expected in 2013-2014 [Jensen, Anna B.O., Mitchell, Cathryn 2011]. It touches upon the preparations going on to face the adverse effects of increased solar activity during the cycle maximum and recommends coordination/cooperation between various relevant organizations/institutions in the processes of data collection and development of a model.
Effect of Flare Angle and Natural Ventilation on The Aerodynamic Characteristics of a Typical Re-Entry Body At Subsonic and Transonic Mach Numbers
Authors: G.K. Suryanarayana
Published: December 2023

Aerodynamic force and moment measurements were carried out on models of a typical re-entry body, featuring a blunt nose, conical body and flare, to assess the effect of flare angle on the overall aerodynamic characteristics. In one of the configurations, the junction between the cone and the flare was vented out to the base of the model to assess the effect of ventilation on the aerodynamic characteristics. It was expected that the stability characteristics would improve, by virtue of improved contribution from the flare to the normal force of the configuration. However, measurements did not show the expected trends. Instead, there was a remarkable reduction in the axial force with ventilation, by as much as 25% all across the Mach number and angle of attack range. Base pressure measurements indicated that in the low Mach number range pressure rise occured. However, in the high transonic Mach number range, even though the force measurements showed drag reduction, there was no significant rise in base pressure. Ventilation showed delay in transonic drag rise. It is therefore suggested that the overall pressure field is modified by ventilation, which results in drag reduction of the configuration.
Growth Opportunities for Composites 2011-2023
Authors: Walker A.M. , Hogg P.
Published: December 2023

Our world will consume 43,000 tonnes per year of carbon fibre in 2010. Published forecasts for Carbon Fibre vary, predicted global demand, in 2020 ranges between 240,000-340,000 tonnes per year. These figures are always revised upwards, never downwards as new business is identified. India’s markets demand should equate to 37,000 tonnes per year in 2020.

Most Carbon Fibre is manufactured from PAN - an expensive and wasteful process. As fibre demand rises prices need to fall. Our ‘eco revolutionary’ world needs a sustainable source of high quality Carbon Fibre.

This paper will explore demand, capacities, alternative precursors and novel fibre spinning technologies.
Approaches and Methods of Evaluation for Composite Materials: Current Trends and the future
Authors: Murthy C.R.L.
Published: December 2023

Critical structures and components utilised in applications such as Aerospace, need special attention in terms of evaluation and establishment of integrity, in particular, in view of the requirements of utmost safety, quality and reliability of performance. Consequently, evolutionary approaches have been imminent and have been taking place since the time of implementation of non invasive methods in their primitive forms utilizing physical principles. However, the approach had taken a totally different direction since the introduction and utilization of newer materials such as composites for primary structural components in aerospace, automotive and several other applications. But, while in practice, the utility and the applicability of the conventional methods and procedures are severely constrained by several factors such as the type of loading, operational environment and more than any other a number of uncertainties associated with real life structures. One simple example is the variation in the mechanical properties of a material. Hence, the approaches that have been followed and are being considered from time to time needed a thorough understanding and development which has been the basis for the evolution of NDT to NDE and currently to SHM. In fact, though SHM is the most recent method of evaluation complementing the existing approaches, it still does not take care of the uncertainties. Thus, some of the recent work oriented towards solving this problem is presented in this paper.
Present Status on Internal Wind Tunnel Balance Technology
Authors: Hufnagel Klaus
Published: December 2023

No abstract
Moisture Absorption, Desorption and Reabsorption Effects on Mechanical Properties of Glass-Epoxy Composites
Authors: Srihari Shylaja , Revathi A. , Vivek Rao R. , Shettigar Satyajith , Bhat Venkatesh , Sriravara Sriram
Published: December 2023

The glass-epoxy composite laminates were fabricated using BID glass fabric and RT cure epoxy matrix by Room Temperature Vacuum Bag Moulding (RTVBM) Technique. The Inter laminar shear strength (ILSS), compression and flexural strength values were determined at room temperature for their dry mechanical property evaluation. The test specimens were exposed to a temperature/humidity condition at 45° C/95% RH for moisture absorption studies. The moisture desorption studies were carried out in a temperature oven at 45° C and 85° C. The mechanical properties of the exposed specimens were evaluated during absorption and desorption conditions. Scanning Electron Microscopy (SEM) studies were carried out on the dry and exposed specimens to determine the effect of moisture on the fracture behaviour of glass-epoxy composites. Results show that, moisture reabsorption and full desorption are faster than the absorption and partial desorption. This may be due to, change of material properties after a cycle of moisture absorption and desorption phenomenon. The mechanical strength (ILSS, compression and flexural) has been found to reduce continuously with increased duration of environmental exposure, but a slight shift back of the strength has been observed for desorbed samples.
Prediction of Thermal Postbuckling Behavior Of Uniform Shear Flexible Column Undergoing Large Lateral Deflections Through An Intuitive Formulation
Authors: Venkateswara Rao G. , Ravi B. , Gupta A.V.S.S.K.S.
Published: December 2023

This paper presents a simple intuitive formulation to predict the thermal postbuckling behavior of uniform shear flexible columns, subjected a uniform temperature rise from its stress free condition, undergoing large lateral deflections. The two ends of the columns are restrained to move axially, so that a mechanical equivalent of the constant compressive load is developed, due to the increase in temperature. The proposed formulation is based on the use of nonlinearities existing in both the axial displacement and lateral deflection, which differs from the von-Karman type nonlinearity due to the moderately large lateral deflections only. In this paper, a simple analytical formula is developed to predict the thermal post buckling behavior of columns, considering both the nonlinearities. The numerical results obtained from the developed intuitive formulas match very well, for the slender columns. Since, there are no results available in the literature, to compare the current results with the case of the shear flexible columns, the authors are of the opinion that the trends of these results, given in this paper, show that there is a reasonable probability that the present results are reliable.
Why Birds and Airplanes Need No Vertical Tail
Authors: Ananthkrishnan Narayan , Sinha Nandan K.
Published: December 2023

The question of why airplanes need a vertical tail whereas birds seem to do very well without one has been longstanding. Some have suggested that it is a matter of scale; that the rationale for a vertical tail disappears when coming down the scale from the regime of "full" scale aircraft to bird/ small scale flight regime. This hypothesis has now been debunked. This paper shows that the lateral-directional modal dynamics and stability criteria remain unchanged over the relevant range of flight Reynolds numbers. It conclusively establishes that a vertical tail is not essential for directional or lateral stability at any scale from that of bird flight to "full" scale airplane flight.
Design and Development of a New 0.5m Hypersonic Wind Tunnel Facility at Indian Institute of Science
Authors: Padbidiri Srikanth S. , Shivashankar B. M. , Nagarjun V. , Naveen H. N. , Vasudevan B.
Published: December 2023

This paper describes the realization of a 0.5m hypersonic wind tunnel, second largest of its kind in India, at the High Speed Wind Tunnel Complex at Indian Institute of Science (IISc), Bangalore. The project was fully funded by the Aerodynamics Panel of AR & DB. There were two major activities associated with the project. One of them pertains to the "Strengthening of the existing 0.3m Hypersonic Wind Tunnel "(originally built in 1985) by adding a new high pressure air compressor, a cascade of high pressure air storage tanks, vacuum pumps and vacuum tanks and another related to establishing "an Additional 0.5m Hypersonic Wind Tunnel Leg". Preliminary commissioning trials of the new facility at low stagnation pressures were conducted in October 2013. Subsequently several hypersonic blow downs were carried out on a variety of models at Mach 8.0. Pitot probe measurements performed in the test section confirmed that the flow Mach number was close to Mach 8.0. The total run time measured was around 10 seconds. Thus, a large 0.5m hypersonic wind tunnel was indigenously designed, developed and commissioned in about 30 months at a cost of Rs.6 Crores. The facility was inaugurated by Prof. R. Narasimha in the presence of a large gathering of leading aerospace scientists in the country, on 8th April 2014.
Novel and Effective Sensor Validation Algorithms For Safety Critical Systems
Authors: Nanda Manju , Jayanthi J. , Arjun T. S.
Published: December 2023

This paper describes a simple, novel and effective implementation and demonstration of sensor validation algorithms for three different and widely used signals for a safety critical embedded application. The challenge in this work was to develop the proposed algorithms with the hardware and system requirement constraints and when there were no off-the-shelf algorithms for this application. The algorithms are developed for analog, discrete and ARINC signals without compromising on the simplicity, reliability and safety. The correctness of these algorithms is verified and validated by means of rigorous laboratory tests and flight trials.
Thermal Postbuckling Analysis of Thin Uniform Square Plates On Winkler Foundation - Effect of Use of Green’s Strain-Displacement Relations
Authors: Venkateswara Rao G. , Ravi B. , Gupta A.V.S.S.K.S.
Published: December 2023

A new simple formulation is developed in this paper, to predict the realistic thermal postbuckling behavior of the square plates, on Winkler foundation. If the plate is subjected to a uniform temperature rise, and also undergoes large deflections, mechanical equivalent inplane compressive, and tensile loads are developed, with the condition of the inplane immovability of the normal edge displacements of the plate. The nature of the distribution of these inplane compressive and tensile loads are similar, but have different magnitudes, which act along the x- and y- directions of the plate. The use of the Green’s nonlinear strain-displacements relations, which do not impose any restriction on the magnitude of the large deflections, to predict the realistic thermal postbuckling loads. The thermal postbuckling results of the plates obtained from this formulation, are validated indirectly, as the corresponding results are not available in the literature, with those of the columns without the elastic foundation. For the non-zero values of the foundation parameter, the present numerical results of the plates, with respect to the central deflection, show the proper physical trends of the nonlinearity, and demonstrate the simplicity of the present formulation.
An Interesting Phenomenon Observed in the Wind Tunnel
Authors: Lal Mangla Niranjan , K Sinha Sumon
Published: December 2023

An extremely high lift was observed over a pitching NACA 0012 airfoil model placed in a low speed subsonic wind tunnel. A leading edge mounted flexible actuator was electrically excited at a given frequency. The excitation power was around 1 W. A 1.5 HP motor, used for pitching the airfoil slowed down and finally stopped. The motor regained its motion when the actuator excitation was stopped. The high lift generated is backed by the pressure measurements made along the central chord axis of the airfoil model. The phenomenon was repeated many times.
Prediction of Sunspot Cycle 24 Based on Geometric Indices of Sunspot Cycles 17 to 23
Authors: Sabarinath A. , Anilkumar A. K.
Published: December 2023

Prediction of the peak amplitude, duration of the rise time, and the length of Sunspot Cycle 24 are made through a statistical analysis using some of the derived parameters called geometric indices of Sunspot Cycles 17 to 23. The geometric parameters considered are: The rate of the ascent phase, rate of the descent phase, maximum amplitude, rise time, fall time, and length. These parameters are computed from cycles 17 to 23. Then, the pair wise correlation between these six parameters computed. A strong correlation is found between the rate of ascent phase and amplitude, rate of the ascent phase and rise time, and the rise time and length. The linear regression models derived from these correlations are directly used to predict the peak amplitude, duration of the rise time, and the length of sunspot cycle 24.The rate of rise computed from the initial 30 months of data is enough to predict the peak amplitude, epoch of the occurrence of peak amplitude and total length of the cycle. The predicted features of smoothed sunspot cycle 24 are: Maximum amplitude of cycle is 73.52 ± 10.6 numbers, length of cycle is 148 ± 7.3 months, i.e., cycle 24 ends between December 2020 and April 2022, and the occurrence of maximum amplitude is 52 ± 3.1 months, i.e, cycle 24 reach to peak amplitude between January 2013 and July 2013.
Design of End Casting for Thin Composite Stiffened Panels Subjected to Axial Compression Load
Authors: Nadeem Masood S. , M Gaddikeri Kotresh , Viswamurthy S.R.
Published: December 2023

Compression testing of large, thin, stiffened composite panels is complex due to the susceptibility of such panels to premature buckling and failure. Such failures are due to the artefacts of testing, such as, offset at load introduction edges, non-uniform distribution of loads, nature of lateral supports, crushing of panel edges etc. In this paper, a novel approach for compression loading of thin stiffened composite panels is proposed and validated from finite element analysis supported by tests. Compression loading of such panels (less than 2mm thick) is challenging since the edges are susceptible to local crushing. To avoid this, loading edges of the panel were encased in mild steel casing blocks filled with finely grounded aluminium powder mixed with epoxy resin. Coupon level tests were conducted to measure mechanical properties of the interface between composite and casting mixture. Digital Image Correlation (DIC) technique was used in these tests to measure the full field strains and to validate numerical simulations. Further, finite element analysis of the actual composite test panel with end casting mixture was performed which indicated that interface shear stresses and compression stresses at maximum expected load are much lower than allowables obtained from specimen tests. Hence, the Aluminium-Epoxy cast mixture proposed in this study can be used safely to cast edges of large stiffened panels for axial compression tests.
Design Point Parameter Estimation of a Legacy Twin Spool Turbojet Engine for Health Monitoring
Authors: Sankar Balaji , Shah Brijeshkumar , Jana Soumendu , Srinivasan Ramamurthy , Satpathy R. K. , Gouda G.
Published: December 2023

The estimation of component parameters of a twin spool turbo jet engine at design point is presented in this paper. Non-linear gas path analysis combined with constrained optimization based technique has been used for the estimation of the engine component parameters and overall performance of the engine. This work needs to be done as the engine manufacturer does not provide these details when supplying the engine to the user. The parameters estimated are pressure ratios and efficiencies of various components such as compressor, turbine and combustor. Parameters estimated were given as input to the simulation model and the error was calculated between simulated gas path parameters and experimental data collected from the engine test bed. It is observed that the simulation results, obtained with estimated parameters, agree closely with experimental data.
Thermal and Mechanical Analysis of FGM Beam Using Generalized Theory
Authors: Kumar Dinesh , Sharma Kanishk
Published: December 2023

A generalized beam theory is developed and used to study the linear-static behavior of an Aluminum-Zirconia Functionally Graded (FG), simply-supported beam subjected to transversely distributed sinusoidal load and non-uniform temperature rise across the thickness of the beam. The Young’s modulus and thermal expansion coefficient of the beam are assumed to vary as per the gradation laws (exponential/power-law) through the thickness, and the Poisson ratio is held constant. The current study is carried out using the developed and properly validated MATLAB codes based on the present formulation. Comparative studies are conducted to examine the effects of various beam theories (i.e., EBT,TBT and RBT derived as especial cases of the generalized beam theory), different material gradation laws and different temperature variations across the thickness of the beam on the stresses and/or displacements of the FGM beam. It is observed that on the contrary to homogeneous beams, thermal stresses in the FGM beam are not zero for the linear variation of temperature along the thickness and these stresses are found to be very much influenced by material distribution laws and indistinguishable for EBT, TBT and RBT. It is also concluded that unlike the corresponding homogenous constituents (i.e., pure ceramic and pure aluminum), the variation of mechanical axial stresses in FGM beam across its thickness is non-linear.
Airborne Separation Assistance during Landing - An Approach for Automation
Authors: Padmashree B. , Subba Reddy B.
Published: December 2023

Self-spacing and Required-Time-of-Arrival (RTA) concepts are now being developed to support future Air Traffic Management (ATM) systems. Among many types of separation methods, distance based separation assumes importance form safety point of view. The present study is an attempt to analyze approach proposed by EUROCAE and extend the same for development of guidance laws in the form of acceleration commands instead of speed commands. Objective is to realize an effective implementation of the guidance laws in the Thrust Management Function of onboard Flight Management System. Simulation studies are presented involving actual flight responses for the lead aircraft during terminal phase.
Bending of Functionally Graded Spherical Shells
Authors: Sai Ram K.S. , Swathi B. , Manjusha K. P. , Srinivasu K.
Published: December 2023

The bending behavior of functionally graded spherical shells with a cutout is studied using the finite element method based on a higher-order shear deformation theory. The higher-order shear deformation theory is derived by assuming that the transverse displacement is constant through the thickness of the shell. Material properties are assumed to be graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. An eight-noded degenerated isoparametric shell element is considered with nine degrees of freedom at each node. The element stiffness matrix and load vector are derived using the principle of minimum potential energy. The formulation and the programme code are validated by comparing the results with those available in the literature. Results are presented for the variation of deflection and stresses in functionally graded spherical shell cap with a circular cutout with simply supported and clamped boundary conditions subjected to uniform normal pressure.
A Bifurcation Theoretic Integrated Methodology for Aircraft Conceptual Design
Authors: Khatri Amit K , Sinha Nandan K
Published: December 2023

A bifurcation theoretic integrated methodology for aircraft conceptual design is presented in this paper. The methodology uses the extended bifurcation analysis technique to formulate a unified design framework that can be applied for configuration sizing of aircraft, assessment of aircraft performance and stability, and evaluation of aircraft maneuverability. Unlike conventional approaches for conceptual design, the proposed methodology incorporates a full six degrees-of-freedom flight dynamics model for stability and control analysis. Maneuverability evaluation is done with the help a suitable controller. Configuration sizing of a six-seater general aviation aircraft, followed by performance, stability and maneuverability assessment of the aircraft is successfully carried out in this paper to demonstrate the effectiveness of the proposed methodology.
Fire Detection System and Spurious (False) Fire Warning Of the Aircraft - An Overview
Authors: Chaturvedi D. K. , Singh Manik Chandra
Published: December 2023

New fire detection technologies are under evaluation for better aircraft safety and risk managements. The goal is to reduce the false alarm rate and to improve safety and reliability features of an aircraft. In this paper, an overview of different types of fire detection system of aircraft is given. Technology currently used for fire detection and protection are discussed. Also analysis and the probable causes of false fire warning of the aircraft are listed along with its future scope of fire protection system for aircraft are discussed.
Unsteady Low-Reynolds Number Aerodynamic Analysis For Flapping Wing Mav Executing a 3D Motion
Authors: Vijayakumar K. , Srinivasan K. V.
Published: December 2023

There is an emerging interest in the field of Nano Aerial Vehicles (NAV) especially of smaller size. These types of vehicles originally developed from the concept of insects, hummingbirds, flying beetles and bats fights. The main objective of this research work is trying to execute a 3D motion (figure of eight) to estimate lift and drag for 3D flapping wing and analysed with the help of computational fluid dynamics, which is related to grid deformation, finite volume method, dynamic mesh and User Defined Function (UDF) for the geometric model with 200mm wing span and 70mm chord. The numerical simulation was carried out at a free stream velocity of 5 m/s. A comprehensive research was carried out to estimate the lift and drag under this condition. The 3D motion helps in better prediction of aerodynamic lift as close to nature and this study is a pointer towards the swarm operations
Force Distribution at Indeterminate Structural Interfaces Of Large Elements of Spacecraft
Authors: K. Renji  , Vivek Prabhakar
Published: December 2023

Spacecraft is an assemblage of several elements and many of these elements have statically indeterminate interfaces. The distribution of forces at their interfaces depends on the stiffness at these interfaces. It is expected that the forces at the interface of a subsystem are significant in regions that are relatively stiff. It is shown here that this behavior is true when the force acts only on the specific subsystem and no forces act on the rest of the elements. If the forces act on the entire system the force distribution at the interface of a subsystem is significantly modified by the deformation at these interfaces which are caused due to the forces acting on the rest of the elements. The forces can be significant even at locations where the stiffness is low. These characteristics are concluded using a spring-mass model. Using the results of finite element model these findings are then demonstrated for the forces at the interfaces of a propellant tank mounted in a spacecraft. Similar characteristics of force distribution are seen in the natural modes of vibration. Experimental results are obtained and they show good agreement with the above findings.
Mimicking the Mechanism of Lift Generation in Dragonflies
Authors: G.K Suryanarayana  , K.M. Naveen
Published: December 2023

Human pursuit of flight has learnt many lessons from nature and a few adaptations have led to phenomenal progress. Insect flight uses complex unsteady aerodynamics to generate lift in addition to producing thrust. A close look at the dragonfly provides some clues to mimic its flight using passive means by separating propulsion and lifting mechanisms. Though the dragonfly can independently flap each of its wings to generate lift and thrust, during forward flight, fore-wings alone flap while the aft-wings remain nearly steady. We adopt this as basis for new passive configurations to generate steady lift. Conceptually, we replace fore-wings with a cylinder that is known to shed vortices, to mimic flapping. A simple plate replaces the aft-wings. Flow analysis of such a configuration at Reynolds Number of 7500 revealed a steady flow topology featuring a trapped vortex over the plate, resulting in steady lift to drag ratio of 3. A further optimized configuration consisting of a semi-circular cylinder upstream and a cambered plate downstream resulted in lift to drag ratio of 14.5, which is considerable for these flow regimes, opening up new possibilities for design of nano-flight vehicles.
Semi Nulling Calibration of a Five Hole Probe
Authors: N. Sitaram
Published: December 2023

Five hole probes are extensively used for measuring three dimensional flows. However the useful range of the probe is limited to about ± 30°. In many flows, this range may be exceeded. In such flows, a seven hole or even a nine hole probe is required increasing testing time or using alternative methods. The objective of the present paper is to find one such alternative method for use of five hole probes in highly three dimensional flows. A large size probe is manufactured and calibrated in an open jet calibration tunnel at a velocity of 40 m/s in yaw angle range of ±90° and pitch angle range of -70° to 90° at an interval of 10°. The probe calibration data is used for nulling calibration with zero yaw angle and pitch angle range of about ± 70°. This method is time consuming. Hence a semi nulling calibration method is developed. This method is similar to non-nulling calibration method. However the range of yaw angle is limited to ± 20°. If the flow yaw angle exceeds this yaw angle range, the probe can be rotated, so that the probe can be used to measure flows with large yaw and pitch angles. The calibration curves of semi nulling method are compared with those of zonal non nulling calibration method. It is found that the pitch angle range of non nulling calibration method is one pitch angle interval less than that of semi nulling method.
Analysis of Moderately Thick Functionally Graded Plates Subjected to Transverse Loads
Authors: S. Srividhya  , A. Rajagopal  , K. Basant  , R.K. Gupta
Published: December 2023

In the present work, flexural analysis of a thin to moderately thick FGM plate subjected to transverse loads have been studied using finite element method. The formulation is developed based on the First order Shear Deformation Theory (FSDT). The mechanical properties are assumed to vary continuously through the thickness of the plate and obey a power law distribution of the volume fraction of the constituents. FGM’s are typically heterogeneous in nature and a homogenization scheme is generally adopted for the analysis. To ascertain the effect of homogenization schemes on the material properties, the variation of volume fraction through the thickness have been computed using two different material homogenization techniques; namely the Rule of Mixtures and Mori-Tanaka scheme. In calculating the effective material properties through the thickness numerical integration have been used to evaluate the integrals which is easier and faster when compared to symbolic integration. A detailed discussion comparing the results from both the homogenization schemes have been presented. In addition to that a detailed parametric study bringing out the effect of boundary conditions, loading intensities and volume fraction index have been presented. Convergence tests and comparison studies have been carried out to demonstrate the efficiency of the present formulation.
Design and Development of Conical/Contour Nozzle For Slow Burning Solid Booster Operating In Sub-orbital Mission
Authors: Parhi Achutananda , Mahesh V. , Ali Mohammad , Dileep K.N. , Levin G. , Eswaran V. , Jayachandran T.
Published: December 2023

In order to optimize the performance of the solid booster operating in sub-orbital altitude the contour of the nozzle needs to be tailored. The conventional convergent/divergent nozzle design is either over or under expanding for the altitude of operation. Therefore, minimizing the flow separation and losses is extremely difficult and cumbersome. In this regard, the divergent portion of nozzle plays vital role to attain the maximum performance with suitable design modification. A novel and promising concept of conical and contour nozzle divergent for slow burning propellant motors operating in sub-orbital altitude is designed and being realized for qualification test. Conical and contour nozzle divergent is a viable solution to avoid flow separation during the lower pressure and lower altitude region of the mission. The design arrived as per the mission requirement, has a conical divergent up to 737 mm from throat plane and third order polynomial profile up to exit, which will give a turn back angle of 5°.The injection point of Secondary Injection Thrust Vector Control System (SITVC) of nozzle is chosen at 45% of total distance from throat plane to exit plane. The present study brings out the theretical estimations of a conical/contour nozzle perfromance with a slowest burning solid booster operating at lower altitude, < 35 km. Theoretical Computational Fluid Dynamics (CFD) simulation study is carried out to assess the effect of nozzle profile on the flow transition. The basic design methodology adopted to avoid flow separation and the governing formulations are presented in this paper.
Effect of Protrusions on the Surface Flow and Pressure Fluctuations in the Inter-stage Region of A Launch Vehicle Model
Authors: Suryanarayana G.K , Sivaramakrishnan A.E.
Published: December 2023

Experiments were carried out to assess the effects of geometrically scaled and viscous scaled protrusions on the surface flow and unsteady pressures in the inter-stage region of a typical launch vehicle model in the Mach number range 0.8 to 1.6. Formation of bow-waves due to the protrusions, and three-dimensional boundary layer separations and reattachments of the shear layer were seen from flow visualizations. Measurements of unsteady pressures show that protrusions cause substantial increases in fluctuation levels on the core vehicle. The highest levels on fluctuations were found to be at a location behind the viscous scaled protrusion, close to the shear layer reattachment. The spectra of pressure signals suggest that the reattachment may be periodic in the range 0.90 £ M £ 1.60; the associated frequency was found to vary in the range 1 kHz to 3.2 kHz (corresponding to Strouhal number in the range 0.034 to 0.051) depending on M. Streamlining the viscous-scaled protrusion was found to replace bow-waves with multiple oblique shocks, resulting in reduced levels of pressure fluctuations, comparable to the basic levels.
Numerical Investigation on the Effect of Geometric Parameters of Chevron Nozzle on Generation of Steamwise Vortices in High Subsonic Jets
Authors: Suvagiya Malay , Sharma S.D.
Published: December 2023

Chevron nozzle is gaining popularity as a noise control device for jet noise reduction. Though it is the only noise control technique currently in use for commercial airliners, complete design methodology of chevrons is not available. In the present work, attempt is made to understand the effect of various geometric parameters of a chevron nozzle on the jet flow using commercial RANS based CFD solvers. Enhancement in mixing, which affects the acoustic signature of the jet, can be attributed to the strength of the streamwise vortices produced by chevrons. Hence major emphasis is given on analyzing the streamwise vortices formed in the jet flow from chevron nozzle. Various geometric parameters like different number of chevrons, their length and tip angles are employed on a 30 mm diameter nozzle producing M = 0.8 jet for further investigation.
Impact Performance of Kevlar Fabrics with Shear Thickening Fluid
Authors: Nashikkar Akshay , Boomurugan R. , Velmurugan R. , Katiyar Ajay , Nandi Tandra
Published: December 2023

In modern day warfare, flexible and light weight body armor, which can provide protection to all the parts of body against all kinds of shrapnel and bullets, is required. The best suited material for its application is Kevlar based bullet proof vest and wearable. However situation requires lesser number of Kevlar layers to make the protective layer which will be extremely light and provide flexibility of motion. To achieve this, a non-Newtonian fluid known as Shear Thickening Fluid (STF) is developed, optimum value is obtained for Kevlar-STF combination and the layers of Kevlar are impregnated with STF. Samples of 4, 6 and 8 layers of Kevlar fabrics are bonded together at the edges by epoxy resin and are subjected to impact loading for different speeds. Experiments are conducted till the ballistic limits of the samples and the ballistic limit values are obtained. The energy absorbed, residual velocities and the ballistic limits of the sample are calculated and compared with theoretically calculated values. Experiments are carried for fabrics with and without STF. It is found that there is a substantial increase in the energy absorption of Kevlar with the addition of STF and the study reveals that the STF based impact resistant structures can be better structural armor material with less number of layers and less weight
MPI-CUDA Implementation of Implicit Euler Flow Solver in Grid-Free Framework
Authors: Bhogendra Rao P.V.R.R. , Ananadhanarayanan K. , Krishnamurthy R. , Chakraborty Debasis
Published: December 2023

Graphics accelerators are increasingly used for general purpose high performance computing applications as they provide a low cost solution to high performance computing requirements. However, the existing application software needs to be restructured to suit to the accelerator paradigm. Explicit methods are inherently suitable for parallelization whereas implicit methods are not suitable as the nodes need to be processed in specific order. However, the nodes can be grouped into clusters such that nodes within the cluster are independent and can be processed concurrently. CUDA kernel can be launched separately for each cluster of nodes to process nodes in parallel leading to same computation results as sequential program. One such successful attempt has been made and the speed up obtained along with computation results is presented in this paper.
Stored Torque Torsional Split Hopkinson Bar Apparatus
Authors: Ramagiri Bhaskar , Sekhar Yerramalli Chandra , Naik N.K.
Published: December 2023

Torsional Split Hopkinson Bar (TSHB) apparatus is extensively used for obtaining shear response of the materials in the strain rate range of 102 s-1 to 104 s-1. Even though the stored torque TSHB is widely used, its design and development technique is not readily available. The present work is focused on discussing the design, development and commissioning of Stored Torque TSHB apparatus. Design considerations of structural components of the experimental setup are discussed. Specimen design considerations, data acquisition system requirement and analysis procedure are presented. Physics of the experiment as well as the fundamental equations involved in obtaining shear stress - shear strain response of the specimen material are presented in detail. Further, typical observations on high strain rate shear behavior of composites are given.
Calibration of Miniature Mass Flow Plug for Metering and Control of Intake Duct Flows
Authors: Nath Buddhadeb , Srinivasan N. , Singh D.B. , Sharma Anju , P Vinay Raya , Sampath Rao B. , Danish Tahzeeb Hassan , Jayaprakash C. , K Sathiyamoorthy
Published: December 2023

The results of experimental calibration of 63mm mass flow plug are presented here. An orifice meter was used as a reference along with total pressure rake to calculate mass flow through the intake duct. The calibration was carried out without intake and fore-body at pressurized condition including atmospheric as well as with intake and fore-body at atmospheric condition only. The results showed that the choked area obtained from orifice plate and total pressure rake data is linear. The calibration data obtained from rake data was higher than that of orifice data, which may be due to highly distorted flow at the dump region. The discharge coefficient is comparable to previously carried out calibration of bigger size of 94 mm mass flow plug.
Effect of Stage Loading and Tip Clearance on Tip Clearance Flows in a Centrifugal Compressor
Authors: Sitaram N. , Subramanian P.
Published: December 2023

The present paper reports measurement of periodic static pressures on the casing over the impeller of a low speed centrifugal compressor at different stage loadings and tip clearances. The periodic pressure data is acquired employing the technique called PLEAT. Experiments are carried out in a low speed centrifugal compressor with unshrouded impeller. Twelve holes are provided on the casing in which adapters are attached. A fast response pressure transducer, Kulite XCS-062 5pisd is inserted in the adapters. The pressure transducer measures pressure in terms of voltage. The voltage output is very low. The output voltage is amplified and converted to digital values for further processing of data. Sample results are presented and interpreted. From the measured static pressure, tip clearance flows can be easily identified. Effect of tip clearance and stage loading on tip clearance flows is highlighted.
Effect of Subsonic Compressibility and Constraints on Generation of 3-D Optimal Camber Shapes
Authors: Gupta S.C.
Published: December 2023

A flat surface wing is optimized for minimum induced drag for low and high subsonic Mach numbers. Wing for transport airplane role is considered. Optimal warp is separated into twist and camber. Effect of compressibility is analysed on the camber shape generated for two different Mach numbers. Constraint of lift is firstly used for developing an objective function for drag minimization. Next the lift and wing root bending moment constraints are considered to form objective function. Analysis is made on the resulting camber and twist distributions.
Chandrayaan-2 Successfully Completes One Year in Lunar Orbit
Authors: Guruprasad BR
Published: December 2023

No Abstract.
Experimental Determination of Drag Constant for Slow Moving Axisymmetric Bodies
Authors: Bhardwaj Utsav , Jindal Tejinder Kumar , Verma Suresh
Published: December 2023

A body moving through a fluid experiences drag, which primarily consists of two components: form drag and viscous drag. At high velocities, the form drag predominates whereas at low velocities, the viscous drag predominates. The form drag is characterized by the drag coefficient which is determined experimentally for various configurations. Similarly, the viscous drag is characterized by the drag constant which in turn is known only for specific cases and its generic governing model is not well established yet. The current study puts forward a generalized mathematical model for determination of the drag constant for frontally streamlined small axisymmetric bodies moving slowly through a fully-enclosing fluid at zero angle of attack. It has been accomplished by establishing a governing mathematical model for viscous drag, validating it via wind tunnel experiments and then comparing it with the standard linear drag equation. Conclusively, the drag constant has been determined in terms of the fluid properties and dimensions of the moving body. This paper describes the above-mentioned mathematical model followed by the process of its experimental validation and determination of drag constant.
Reflecting on the Reflections: Using Word Clouds to Assess a Catholic University Core Curriculum and Community-Engaged Learning Course
Authors: Smith Jimmy , Zeisner Catherine , Turcott Ryan
Published: December 2023

The current research utilized a modern word cloud tool to assess the effectiveness of course objectives and outcomes of a community-engaged learning and core curriculum course at a private Catholic University. The foundational course revolves around social justice using the setting of sport and physical activity. Beginning with a final reflection of the course and inserting data into word cloud

tool, results indicate that this assessment technique offered insight into future enhancements of college course assessment by breaking down and focusing on specific words or phrases that may or

may not be meeting the needs of the instructor and students.
NEUROLOGICAL DISORDERS AND PSYCHOMETRIC METHODS OF THEIR ASSESSMENT IN HIV PATIENTS
Authors: Abdullayeva N.R. , Mammadbayli А.K. , Mamedova М.М. , Rzayev R.N. , Маmmedbekov F.N. , Musayeva А.А. , Аlekberova S.P.
Published: December 2023

This article presents the features of neurological disorders most common in HIV patients, as well as the assessment methods in evaluation of neurological problems using various scales for neurocognitive impairment and neuropathy in HIV patients.
DISCONTINUATION (СANCELLATION) OF TREATMENT OF EPILEPTIC SEIZURES
Authors: Magalov Sh.I. , Mammadbayli A.K. , Musayeva A.A. , Mammadova M.M. , Mammadbayov F.N. , Rzayev R.N. , Alekberova S.P.
Published: December 2023

Currently, special attention is paid to the quality of life of patients with epilepsy. Therefore, great importance is given to the possibility of canceling antiepileptic therapy with prolonged remission. Before discontinuation of therapy, it is necessary to conduct electroencephalography (EEG) and determine the level of antiepileptic drugs (AED) in blood plasma. The presence of signs of typical epileptic activity on the EEG is a likely question of the correctness of the chosen tactics and the need to identify possible symptomatic mild seizures has no clearly defined standards for reducing the dosage of AED. On the recommendation of some experts, benzodiazepines and barbiturates are canceled within 4-8 weeks, with a combination therapy with a break for each drug of 1 month for 4-8 weeks for each.