bluuebunny/crossref_metadata_2025 huggingface dataset:
A Hybrid ML Sentiment Analysis for Climate Change Management in Social Media
Authors: Davuluri Sandeep Kumar , Kanulla Lakshman Kumar , Pothakamuri Lakshmi Narayana
Published: October 2024

Carbon dioxide and other greenhouse gas emissions into the biosphere cause global warming, which in turn causes climate change. Sentiment analysis, particularly on microblogging platforms like Twitter, has garnered a lot of attention from academics in recent years due to the mountain of data generated by contemporary climate change arguments. However, there is a dearth of research on the effectiveness of different sentiment analysis methods via lexicon, machine learning, and mixed methods, particularly when it comes to this specific sentiment peculiar to this area. This research aims to assess and distinguish between several sentiment analysis methods to identify the best method for assessing tweets on climate change and related subjects. Seven lexicon-based techniques—SentiWordNet, VADER, SentiStrength, TextBlob, Hu and Liu, and WKWSCI—were used in this study.
Harnessing AI for Climate Resilience
Authors: Ashok P. , Biswas Kirti Kaushik , Shreenidhi K. S. , Anandaram Harishchander , Karthikeyan G. , Ravindaran F.
Published: October 2024

Reducing time taken to respond to climate events, AI also helps manage resource usage for higher climate resilience besides helping with superior analytical abilities. The effects of the extreme weather can be prevented and the impact of such a calamity reduced by using models that are AI driven to analyze a large amount of data regarding the environment, in order to forecast catastrophic weather conditions. In agriculture, food security is avengers by AI managing irrigation and crop grades based on the changes in climate. Thus, integrating AI into climate strategies, it is possible to create efficient adaptive, resilient systems that anticipate and respond to the adverse effects of climate change.Additionally, it suggests that the article will examine the current state of Artificial Intelligence in climate change and give 13 suggestions on how to find and use AI's chances to fight climate change while minimizing its negative environmental effects.
NLP Techniques to Achieve the Detection of Climate Change in Text Corpora
Authors: Vivek Tammineedi Venkata Satya , Veeranna Thotakura , Prasad V. V. Siva , Rani N. Sudha , Rao A. Srinivas , Selvan R. Senthamil
Published: October 2024

Financial intermediaries have been pressing corporations to disclose financial risks associated with climate change, particularly from individual and institutional investors. To detect these kinds of hazards in their financial and non-financial reports, companies should be required to publish a significant quantity of textual data shortly. This is especially true in light of the expanding regulations that are being enacted on the subject. To do this, this research uses cutting-edge natural language processing algorithms to identify changes in climate in text datasets. Two transformer models BERT and ClimateBert, a freshly released DistillRoBERTa-based model especially designed for climate text classification are refined using transfer learning. These two algorithms can learn contextual linkages between words in a text since they are based on the transformer architecture. To fine-tune these models, the researcher employ the novel “ClimaText” database, which contains information sourced from Wikipedia, and 10,000 file reports, including web-based claims.
Analysing the Textual Analysis of Different NLP Techniques to Classify the Stability of Corporate Reporting
Authors: Asghar Bilal , Abdulrahman Alhazemi A. , Devaraj Rajesh , Patro Pramoda , Anand M. Clement Joe
Published: October 2024

Presently, in certain cases, unstructured material like annual reports, news articles, and earnings call transcripts may give valuable sustainability data. Currently, scholars and specialists have started the collection of data from many sources employing a wide array of natural language processing (NLP) techniques. Although nearby many benefits to be obtained from these efforts, studies that use these techniques often fail to consider the accuracy and effectiveness of the selected approach in capturing sustainability information from text. This method is troublesome due to the variability in outcomes that arise from using multiple NLP algorithms for information extraction. Therefore, the selection of a particular approach might have an impact on the output of an application and subsequently influence the conclusions that users get from their findings. This research investigates the impact of several NLP techniques on the accuracy and excellence of retrieved information. The researcher specifically analyses and contrasts four main methods.
Navigating the Abyss
Authors: Mukherjee Anshit , Gupta Avishek , Das Sudeshna , Banerjee Sohini
Published: October 2024

Text mining has emerged as a very popular tool in the past years and helped in concluding valuable facts from widespread heterogeneous data in domain of climate science. When we navigate through the abysses of the text data from climate science domain there are many challenges that needs attention to use the maximum potential of this approach. The paper first highlights those voids that needs to be filled with detailed literature review followed by an innovative algorithm with detailed explanation how the algorithm overcomes the mentioned voids previously stated. Empirical validation and graphical interpretation are also provided to support the efficiency of our algorithm in comparison with other existing advanced algorithms in this domain presently in use. Also, we mentioned challenges evolved due to our new algorithm followed by future scopes and conclusion.
Drivers and Impacts of Text Mining on Climate Change
Authors: Selvakumar P. , Seenivasan S. , Athavale Vijay Anant , Poorani S. , Das Abhijeet
Published: October 2024

The drivers and impacts of text mining on climate change have been extensively explored in this book. We have seen how text mining has emerged as a powerful tool for extracting insights from vast amounts of text data related to climate change. The chapters in this book have demonstrated the various applications of text mining in climate change research. The drivers of text mining on climate change include the increasing availability of text data, advancements in natural language processing, and the need for more effective climate change mitigation and adaptation strategies. Text mining has been applied to various text data sources, including scientific articles, news stories, social media posts, and government reports. The impacts of text mining on climate change have been significant, enabling researchers to identify key themes and trends, extract relevant information, and uncover hidden patterns and relationships. Text mining will become more crucial as text data volume and complexity increase in tackling the pressing issues brought on by climate change.
Text Mining in Climate Change Communication and Corporate Sustainability Reporting
Authors: Balaji K.
Published: October 2024

In the contemporary landscape of corporate sustainability, understanding stakeholder perceptions of climate initiatives is paramount. This study explores the application of text mining and sentiment analysis techniques to evaluate corporate sustainability reports, social media posts, and stakeholder communications. By leveraging advanced natural language processing (NLP) tools, we aim to uncover the sentiment and thematic trends associated with corporate climate initiatives. The research focuses on analysing large datasets from various sources, including annual sustainability reports. Our findings indicate a diverse range of sentiments towards corporate climate actions, highlighting areas of both approval and criticism. By mapping these sentiments, the study provides insights into how companies can enhance their communication strategies to foster better stakeholder engagement and trust. Furthermore, this research underscores the importance of continuous monitoring and analysis of stakeholder feedback as a dynamic component of corporate sustainability practices. .
Application of Multimedia Information Retrieval Technology in Japanese Text Content Information Query Platform
Authors: Pan Xiaoning
Published: October 2024

The research and development of Japanese operating platform has become a new industry. At the same time, it is necessary to strengthen the research on query and feedback technology in MIR(Multimedia Information Retrieval). Based on this, this paper introduces the research status and progress of query and feedback technology in multimedia retrieval, and introduces the overall framework and technical links of MIR. This paper discusses the application of MIR technology in Japanese text content information query platform. A new multimodal retrieval mechanism is proposed, which combines cross-reference index and underlying features in retrieval and related feedback to realize unified processing of multimodal data. The time consumption of the algorithm is lower than that of the two comparative algorithms, which also verifies the superiority. It is feasible to apply the MIR technology proposed in this paper to the Japanese text content information query platform. It provides a new path for Japanese text content information retrieval.
Applied Learning for Developing Knowledge on Artificial Intelligence Among Students
Authors: Lu Faxin , Liu Sunfa
Published: October 2024

As technology advances in the twenty-first century, innovative approach has been identified for developing skills on artificial intelligence (AI) technologies among students. Hence, to continuously improve the knowledge acquisition process, it is important that university lecturers embrace applied learning for developing hands-on competencies of students. Through applied learning, educators can disseminate knowledge on AI by engaging in the direct application of their expertise and theories, resulting in in-depth understanding by the students. A narrative review technique supported with a theoretical interpretation from ADDIE was applied. Findings revealed that applied learning is suitable for educators to develop and sustain hands-on skills and competencies on AI among students. The five steps of the theory lead to practical change and development, while being able to strengthen the change achieved. Through analyzing, designing, developing, implementing, and evaluation of teaching and training contents, the final goal of transforming students' knowledge on AI is achieved.
DO DIREITO AO TERRITÓRIO E À MOBILIDADE: ANÁLISE DAS PROPOSTAS ENVIADAS À IV CONFERÊNCIA NACIONAL DE JUVENTUDE
Authors: Oliveira Victor Hugo Nedel
Published: October 2024

Verifica-se, na Geografia brasileira, a formação de um novo subcampo do saber, denominado “Geografias das Juventudes”. Nesse sentido, reconhece-se a importância de se analisar, espacialmente, as questões relacionadas a esses sujeitos, como é o caso dos debates realizados durante a IV Conferência Nacional de Juventude. Por isso, o objetivo do presente artigo é investigar as propostas debatidas no referido evento, relacionadas ao eixo “Do Direito ao Território e à Mobilidade”, debate integralmente relacionado com os estudos geográficos. Para tanto, procedeu-se à análise documental do Caderno de Propostas IV Conferência Nacional de Juventude, especificamente analisando as 13 propostas que foram encaminhadas para discussão no eixo Do Direito ao Território e à Mobilidade. Os principais resultados apontaram para a expansão irrestrita do passe livre para jovens, a ampliação dos modais do IDJovem e a promoção da regularização fundiária, a promoção de mobilidade sustentável, requalificação de estradas, inclusão de conteúdos educacionais sobre território, descentralização de políticas públicas, e a garantia de direitos específicos para comunidades tradicionais. É possível considerar, a partir do estudo realizado, que as políticas resultantes dos debates não apenas atendam às diversas necessidades do presente das juventudes, mas também construam um futuro mais equitativo e promissor para as próximas gerações.
Acoustic Characterization and Prediction of Representative, Small-Scale Rotary-Wing Unmanned Aircraft System Components
Authors:   NASA Langley Research Center, Zawodny Nikolas , Boyd D. , Burley Casey
Published: October 2024

In this study, hover performance and acoustic measurements are taken on two different isolated rotors representative of small-scale, rotary-wing unmanned aircraft systems (UAS) for a range of rotation rates. Each rotor system consists of two fixed-pitch blades powered by a brushless motor. For nearly the same thrust condition, significant differences in overall sound pressure level (OASPL), up to 8 dB, and directivity were observed between the two rotor systems. Differences are shown to be in part attributed to different rotor tip speeds, along with increased broadband and motor noise levels. In addition to acoustic measurements, aeroacoustic predictions were implemented in order to better understand the noise content of the rotor systems. Numerical aerodynamic predictions were computed using the unsteady Reynolds-averaged Navier Stokes code OVERFLOW2 on one of the isolated rotors, while analytical predictions were computed using the Propeller Analysis System of the Aircraft NOise Prediction Program (ANOPP-PAS) on the two rotor configurations. Preliminary semi-empirical frequency domain broadband noise predictions were also carried out based on airfoil self-noise theory in a rotational reference frame. The prediction techniques further supported trends identified in the experimental data analysis. The brushless motors were observed to be important noise contributors and warrant further investigation. It is believed that UAS acoustic prediction capabilities must consider both rotor and motor components as part of a combined noise-generating system.
Computational Comparisons between FW-H and Direct Acoustic Predictions
Authors:   Bain Aero LLC, Bain Jeremy
Published: October 2024

Acoustic calculations are made for a three blade single and dual rotors in hover using conventional acoustic analogy and directly from the CFD solver. The acoustic results directly from overset CFD solver with high order finite-difference schemes were able to produce remarkably similar results to the acoustic analogy solver out to ten radii. In the near field, the results directly from the solver were substantially higher than the acoustic analogy calculations. The off body grid density was increased to improve the resolution at up to ten radii away from the rotor. The computed results showed no numerical dissipation as long as there were at least four grid points per acoustic wavelength. Minimal dissipation was seen with at least two grid points with large numerical dissipation for less than one grid point per wavelength. The dual rotor results showed very similar patterns of acoustic constructive and destructive interference. The regions of interference showed some difference between the methods. Overall, acoustic computations directly from the CFD solver are shown to be comparable to conventional acoustic analogy computations while also having the ability to directly account for complex geometry. Grid density does need to be increased for the direct acoustic calculation but the overall increase can be limited to only the direction of interest. High frequency results at higher multiples of the blade passage frequency require greater grid density limiting direct calculations to the lower blade frequencies.
Innovative Rotor-state Measurements Enabling Helicopter In-flight Noise Monitoring and Enhanced Attitude Control
Authors:   Politecnico di Milano, Trainelli Lorenzo ,   Universita di Roma Tre, Gennaretti Massimo ,   Finmeccanica - Helicopter Division, Redaelli Matteo ,   Vicoter, Cordisco Potito ,   Logic, Grassetti Riccardo , Lovera Marco , Rolando Alberto , Zappa Emanuele
Published: October 2024

We give a comprehensive illustration of a new approach to rotorcraft noise abatement carried out in the framework of the Clean Sky collaborative project MANOEUVRES. This approach is based on technologies and tools for real-time, in-flight monitoring of the emitted noise. By means of a new cockpit instrumentation, the Pilot Acoustic Indicator (PAI), the current noise impact is presented to the pilot in a condensed, practical form as an aid in performing quieter maneuvers. The PAI algorithm makes use of several ingredients that have been implemented and tested within the project, including offline steady and unsteady acoustic predictions, and estimation of flight mechanics parameters based on the measurements derived from a new contactless rotor state measurement system. The latter is capable to accurately acquire the motion of the rotor blades, allowing the computation of non-directly-measurable quantities such as tip-path-plane angle of attack and thrust coefficient, and offering a reliable support for the development of enhanced attitude control laws based on the Rotor State Feedback approach. The paper reports on the current state of the project, which is close to its completion.
Helicopter Community Noise Prediction Methodology for AEDT
Authors:   John A. Volpe National Transportation Systems Center - US Dept. of Transportation, Page Juliet
Published: October 2024

The approach to this project was to identify a series of targeted comparison/sensitivity mini-studies identified as important and relevant which were used to assess model accuracy and the influence of the various modeling features on the predictions. In conjunction with the mini-studies, published validation results, modeling physics documented in the literature, and an understanding of the models themselves, the following framework elements and potential improvements for AEDT were identified and prioritized. Subsequent sections present the rationale for each recommendation.
An Acoustic Investigation of a Coaxial Helicopter in High-Speed Flight
Authors:   The Pennsylvania State University, Walsh Gregory ,   Rensselaer Polytechnic Institute, Jacobellis George , Brentner Kenneth , Gandhi Farhan
Published: October 2024

The desire for a vertical takeoff and landing (VTOL) aircraft capable of high forward flight speeds is very strong. Compound lift-offset coaxial helicopter designs have been proposed and have demonstrated the ability to fulfill this desire but, with high forward speeds, noise is an important concern that needs to be addressed. The study in this paper utilizes a Rotorcraft Comprehensive Analysis System (RCAS) model of the XH-59 aircraft, in conjunction with a noise prediction code, PSU-WOPWOP, to computationally explore the acoustics of a lift-offset coaxial helicopter. Specifically, unique characteristics of the XH-59 coaxial helicopter noise are identified; and design features and trim settings specific to a compound coaxial helicopter are considered for noise reduction. At some observer locations, there is constructive interference of the coaxial acoustic pressure pulses, such that the two signals add completely. The locations of these constructive interferences can be altered though, by modifying the upper-lower rotor blade phasing, providing an overall acoustic benefit. Significant noise reduction (and power reduction) is possible by reducing rotor tip speeds - an option available because the coaxial rotor in a compound configuration does not need to provide all the propulsive force. A dual-swept tip blade also enables noise reduction at an in-plane, forward, target observer. Compete CFD analyses, coupled with PSU-WOPWOP, should be explored in the future for a comprehensive acoustic evaluation of lift-offset coaxial helicopter noise.
Experimental Measurement of a Blade Section With a Continuous Trailing-Edge Flap
Authors:   US Army Research Laboratory, Thornburgh Robert , Kreshock Andrew , Wilbur Matthew
Published: October 2024

This paper presents the experimental bench-test and wind-tunnel-test results for a prototype rotor-blade section with an integrated Continuous Trailing-Edge Flap (CTEF). The CTEF is a monolithic active blade design that uses piezoelectric-fiber actuators to deform the trailing edge of an airfoil, and thereby induce changes in lift and pitching moment. Based on prior analytical modeling, a CTEF test article was manufactured and subjected to bench testing and low-speed wind-tunnel testing. Bench testing was conducted over a range of actuation frequencies and voltages, and the deformation of the airfoil section was measured. In the wind tunnel, deflection under aerodynamic load and the aerodynamic performance were measured. Measured performance was slightly less than predicted, but the results demonstrate that the CTEF concept does perform as expected.
Nonlinear Aeroelastic Model for a Highly Flexible Flapping Wing in Hover
Authors:   Texas A&M University, Yang Xuan , Sudhir Aswathi , Benedict Moble
Published: October 2024

This paper presents a standalone coupled aeroelastic framework for highly flexible flapping wings in hover for Micro Aerial Vehicle (MAVs) application. A realistic hover-capable flapping-wing MAV utilizes highly flexible wings operating at high frequencies/amplitudes, which causes extreme wing deflections and highly unsteady, vortical flows. The strong fluid-structure coupling and the complicated flow physics make the performance of such a system extremely difficult to predict. In the present model, in order to accurately capture the large nonlinear wing deflections, a geometrically exact shell theory has been adopted. A potential-flow-based unsteady aerodynamic model is then coupled with the fully nonlinear structural model to generate high fidelity coupled aeroelastic framework. Both the structural and aerodynamic models are validated independently before coupling. The coupling process required spatial and temporal interpolation functions for the two models to communicate with each other. An innovative flapping wing experimental setup was designed and built to measure the time-history of lift forces acting on a flexible wing during a flap cycle. The instantaneous lift force predictions from the coupled aeroelastic model is compared with the results from the in-house flapping wing experiments at moderately high frequencies.
Development of the World's Smallest Cyclocopter
Authors:   Texas A&M University, Runco Carl , Coleman David , Benedict Moble
Published: October 2024

This paper describes the design, development and flight testing of a meso-scale cyclocopter. Weighing only 29 grams, the present vehicle is the smallest cycloidal rotor based aircraft ever built. Unlike the previous cyclocopters, the current prototype utilizes a novel, light weight (3 grams) cycloidal rotor design, with cantilevered blades, having semi-elliptical planform shape and no exposed rotor shaft. To minimize bending deflections the blades use a unique, lightweight (0.15 grams each) but high strength-to-weight ratio unidirectional carbon-fiber based structural design and are fabricated using a specialized manufacturing process. The cycloidal rotor design was chosen through systematic performance measurements conducted using a custom-built miniature three-component force balance. Based on experimental parametric studies, a 4-bladed rotor and symmetric blade kinematics with pitch amplitude of 45° provided the highest thrust and power loading (thrust/power) and was used in the final rotor design. The airframe is fabricated using a combination of carbon-fiber and state-of-the-art 3D printing techniques. The attitude control strategy utilizes a combination of rpm-control of the two cycloidal-rotors/tail-rotor and thrust vectoring of the cycloidal rotors. The control strategy is implemented on a custom-built 1.3 gram autopilot, which uses a closed-loop proportional-derivative controller for hover stability. The vehicle has been systematically flight tested by tuning the feedback gains and has demonstrated stable hovering flight.
Analysis Methods For Advanced V/STOL Configurations
Authors:   Continuum Dynamics Inc., Quackenbush Todd , Keller Jeffery , Whitehouse Glen
Published: October 2024

This paper features an assessment the capabilities of several advanced analysis tools for addressing key aerodynamic design issues faced by several prominent classes of VTOL vehicles currently under study. The assessment summarizes the strengths and limitations of a suite of modeling tools - a comprehensive rotorcraft model, a Cartesian grid Euler model, and an unstructured URANS analysis - in matching available data involving ducted propeller and proprotor/wing interactions representative of those faced by candidate compound, tiltrotor/ tiltwing, and tailsitter configurations. The intent is to provide insight into the analysis challenges for vehicles involving such design features, the potential of these classes of tools for addressing them, and to motivate possible method upgrades. While the primary application for these methods likely will be for advanced vehicles of the type sought by the U.S. Army Future Vertical Lift program and/or the DARPA V/STOL X-Plane and TERN programs, they could be applicable to a wide range of current and future advanced VTOL vehicles, including unmanned aircraft systems.
Rotor-Obstacle Aerodynamic Interaction in Hovering Flight: An Experimental Survey
Authors:   Politecnico di Milano, Zagaglia Daniele ,   University of Glasgow, Giuni Michea , Green Richard
Published: October 2024

Despite the presence of a fair number of numerical and experimental works on the rotor-obstacle interaction, a systematic study of the aerodynamic phenomena involved is lacking. In this paper a comprehensive experimental survey carried out at University of Glasgow is described, taking advantage of two different rotor rigs and several experimental techniques. Load measurements on the rotor were carried out in order to assess the rotor performance for different positions with respect to a cubic obstacle, thus simulating a set of possible hovering flight conditions around the obstacle. Laser Doppler Anemometry (LDA) measurements of the rotor inflow were used in order to investigate how the aerodynamic interaction affected the rotor performance. Eventually Stereoscopic Particle Image Velocimetry (SPIV) measurements in the region between the rotor and the obstacle were carried out in order to have a better insight of the interacting flow field.
Wind Tunnel Assessment of the Computational Framework for Helicopter Fuselage Drag Reduction Using Vortex Generators
Authors:   Politecnico di Milano, Zanotti Alex ,   ONERA - The French Aerospace Lab, Boniface Jean-Christophe , Droandi Giovanni , Gibertini Giuseppe , Auteri Franco , Gaveriaux Robert , Pape Arnaud
Published: October 2024

A comprehensive wind tunnel campaign was performed to assess the results of a computational framework aimed to study the optimal layout and position of vortex generators for helicopter fuselage drag reduction. The most promising vortex generators configurations indicated by the numerical study were tested on a heavy-class helicopter fuselage model. The experimental activity, including loads, pressure measurements and stereo particle image velocimetry surveys, confirmed the main trends predicted by numerical simulations. In particular, the wind tunnel tests results showed that the best array of vortex generators positioned on the model back-ramp downstream the fuselage upsweep produces a maximum drag reduction of about 5% with respect to the measured clean fuselage drag. Moreover, velocity fields and pressure distributions evaluated around the backdoor/tail-boom junction enabled to investigate the flow physics related to the vortex generators functioning for fuselage drag reduction.
Numerical and Experimental Study of Centrifugally-Driven Flow inside a Rotating Duct for Rotorcraft Application
Authors:   United Technologies Research Center, Min Byung-Young ,   The University of Texas at Austin, Karpatne Anand ,   Sikorsky Aircraft, Sargent D. , Shannon Daniel , Wake Brian , Sirohi Jayant
Published: October 2024

Rotor blades experience very high centrifugal forces that can be utilized to pump air to the outboard region of the blade through an internal duct, which can be used for flow control. Analysis or design of such systems requires accurate prediction capability. In order to validate current Reynolds Averaged Navier-Stokes CFD methodologies, an experiment was performed using a rotating pipe as a simplified ducted blade, and simulation results were compared to the measured data. A quasi-one-dimensional (Q1D) code was also compared to experimental data as a lower order simulation tool that can provide faster solutions more appropriate for rapid design iterations. The test and simulations include several combinations of steady inlet and exit conditions as well as an unsteady inlet valve operation condition at several rotational speeds. The Q1D code showed good correlation for steady inlet and exit conditions with boundary conditions obtained from experiment. Navier-Stokes CFD methods also showed good agreement with measured data for pressure and mass flow rate at most conditions, while properly capturing complex flow features including separation, secondary swirl flow, and tip-flow interactions. The Kinetic Eddy Simulation and the Spalart-Allmaras turbulence models were tested to examine solution sensitivity under the complex flow environment. The two turbulence models showed similar results, except when the inlet valve was closed, in which case, the Kinetic-Eddy-Simulation model showed better correlation.
Experimental Investigation of Passive and Active Flow Control for X2 Technology Hub and Fuselage Drag Reduction
Authors:   United Technologies Research Center, Bowles Patrick ,   Sikorsky Aircraft Corp., Geiger Derek ,   Aviation Development Directorate, Thomas Mathew , Botros Barbara , Matalanis Claude , Min Byung-Young , Wake Brian
Published: October 2024

The effects of passive, active, and combined flow control on the aerodynamic performance of an unpowered, bladeless 1/5th scale model of the X2 Technology™ Demonstrator have been assessed through a variety of surface and off-body measurements in a low-speed wind tunnel test, Re = 88x10³ [1/ft] and M∞ = 0.13. The baseline model employs a state-of-the-art low-drag coaxial hub design. Further drag reduction was investigated through minor design alterations, endplates, vortex generators, steady blowing and suction, and oscillatory blowing. Each drag mitigation control approach was individually assessed. Flow control technologies that produced the most promising test results were combined for further augmented performance. Six-component external balance loads, independent hub and tail loads, and surface and wake flow and pressure measurements were used to determine aerodynamic performance and the detailed physics of the flow control attributes. The wind tunnel test showed that the addition of endplates provided vehicle drag reduction of 4%. Steady blowing from the rotor shaft fairing reduced drag 4% and the combination of endplates and blowing decreased drag 6-8%.
Effects of Time-Varying Flow Velocity on Steady Blowing Flow Control for a Pitching Airfoil
Authors:   The Ohio State University, Naigle Shawn , Frankhouser Matthew , Gregory James , Bons Jeffrey
Published: October 2024

This work presents results of an experimental investigation into the effect of time-varying free stream on active flow control of a Sikorsky SSC-A09 airfoil undergoing periodic pitching motion using supersonic, leading edge vortex generator jets. The airfoil was evaluated at reduced pitching frequencies of k=0.026 to k=0.05 at Mach 0.4+0.07cos(ωt) at a mean Reynolds number of 3.0x10⁶. A spanwise row of vortex generator jets located at 10% chord blowing at a jet mass flux ratio (Cq) of 0.001-0.005 demonstrated improvements in both CL and CM hysteresis loops and reductions in negative damping. Initial data indicates that the interaction between VGJ blowing and a time-varying flow delays flow separation during the pitch-up and accelerates flow reattachment during the downstroke. Post-stall shear layer instabilities and airfoil load oscillations are amplified. The VGJ interaction with the shear layer results in an increase in aerodynamic performance determined by the surface pressure taps and illustrated by the use of Background Oriented Schlieren (BOS) as a flow visualization technique.
A Space-Time Accurate Finite-State Inflow Model for Aeroelastic Applications
Authors:   Roma Tre University, Gennaretti Massimo , Gori Riccardo , Cardito Felice , Serafini Jacopo , Bernardini Giovanni
Published: October 2024

Dynamic wake inflow modelling is one of the main issues in the development of efficient and high-fidelity simulation tools for design of new generation rotorcraft. The aim of this paper is the development of a LTI, space-accurate, finite-state model for the prediction of dynamic wake inflow perturbations of helicopter rotors in arbitrary steady flight, extracted from high-fidelity aerodynamics solvers. The proposed dynamic wake inflow model, coupled with sectional aerodynamic load theories, may be conveniently applied for aeroelastic and aero-servo-elastic analysis of rotors with the introduction of a limited number of additional states, thus turning out to be suitable for real-time predictions. The outcomes of numerical investigations concerning a helicopter rotor in hovering and forward flight conditions are shown to demonstrate the capability of the introduced model to capture with a good level of accuracy the time evolution of the wake inflow radial distribution on blades of rotors subject to arbitrary perturbations.
Adjoint-based Aeroacoustic Design-Optimization of Flexible Rotors in Forward Flight
Authors:   University of Wyoming, Fabiano Enrico , Mavriplis Dimitri
Published: October 2024

This paper presents the development and application of a time-dependent adjoint-based method for aeroacoustic design optimization of flexible helicopter rotors in forward flight. The rotor noise signature at a farfield observer is computed with the hybrid aeroacoustic approach in which a near-body coupled computational fluid dynamics/ computational structural dynamics solver provides flow and geometry data to an FW-H acoustic module that propagates the acoustic waves to a farfield observer. Forward and adjoint sensitivity formulations are derived that correspond to analogues of the multidisciplinary flexible aeroacoustic analysis problem. The newly implemented aeroacoustic capability is first verified to effectively perform forward flight noise prediction by comparison with the PSU-WOPWOP acoustic tool. Upon successful validation, a gradient based optimization method is used to minimize the required torque of the flexible HART-II rotor in trimmed forward flight while reducing the acoustic signature at a farfield observer by changing the shape of the blades. The adjoint formulation developed in this work is used to efficiently compute the sensitivity required by the optimization algorithm.
Evaluation of Transitional Effects in Rotorcraft Applications
Authors:   Georgia Institute of Technology, Cross Philip , Hodara Joachim , Smith Marilyn
Published: October 2024

Transition in computational simulations is still an emerging area of algorithm development for rotorcraft applications. It, along with turbulence modeling, is assumed to be the source of errors in many numerical analyses. To explore the influence of transition, two transition methods are analyzed across different configurations of interest to rotorcraft. The Langtry cross flow model for Reynolds-Averaged Navier-Stokes (RANS) solvers and a consistent transition approach to the Georgia Tech hybrid Reynolds-Averaged Navier-Stokes and Large Eddy Simulation (RANS-LES or HRLES) are evaluated. The configurations include a prolate spheroid, a rotor-body interaction (ROBIN) generic model fuselage, and a two-dimensional yawed wing. The solutions indicate the importance of not only transition, but also crossflow transition on rotor and fuselage aerodynamic behavior.
Assessment of Transition Models in Predicting Skin Frictions and Flow Field of a Full-Scale Tilt Rotor in Hover
Authors:   The University of Toledo, Sheng Chunhua , Zhao Qiuying
Published: October 2024

Two transition modeling methods are assessed for predicting the skin frictions and flow field of a full-scale, hovering XV-15 tiltrotor using an unsteady Reynolds-averaged Navier-Stokes (RANS) flow solver. The rotor Figure of Merit (FM) is predicted over a range of collective pitch angles at two tip Mach numbers: a design tip Mach number of 0.69 and a reduced tip Mach number of 0.56. Computed skin frictions are compared with the measured data at selected collective pitch angles of 3°, 10°, 14° and 16.6°. The Langtry-Menter γ - Reθt transition model is integrated into Spalart-Allmaras's one-equation turbulence model (SA-TM) as well as Menter's shear stress transport two-equation turbulence model (SST-TM). Both SATM and SST-TM transition models are assessed for predicting the laminar separation-induced transition and the mid-chord flow separation phenomena on the XV-15 rotor. A method to correct premature flow separation is introduced to improve the model's behavior in predicting the hover performance and flow field for the XV-15 rotor at high thrust levels. Predicted skin frictions and hover performance show strong conformity with the wind tunnel measurements.
Performance and Flowfield Measurements of Rotors with Pumping Blades
Authors:   United States Naval Academy, Milluzzo Joseph , Drayton Scott , Branson Benjamin
Published: October 2024

High-resolution particle image velocimetry measurements were taken to document the initial roll-up and evolution of the tip vortices trailed from a rotor operating in ground effect with pumping rotor blades. The pumping blade design utilized an internal duct connecting the intake slot near the root of the blade with exit slots at the blade tip. The baseline non-pumping and pumping blades were tested in a hovering state in ground effect at a blade loading coefficient of 0.080. Performance measurements were taken both out of ground effect and in ground effect to examine the effect of the Coriolis torque generated by the pumping blades. A first-order theoretical investigation of the Coriolis torque was performed using a one-dimensional, incompressible, fully developed, steady flow analysis on the flow through the internal duct. The method yielded a simple equation that was determined to be highly dependent on the assumed conditions of the internal flow (e.g., laminar, turbulent, etc.). The spanwise blowing of the pumping blades initially generated a vortex core that was significantly more distorted than the baseline blade but this initial distortion was overcome by the rotation of the vortex. Furthermore, the pumping blades produced significantly more diffused tip vortices, producing peak swirl velocities approximately half that of the vortices produced by the baseline blades.
Assessment of Turbulence Model Length Scales based on Hybrid RANS-LES Modeling of Unsteady Flow Over Airfoil
Authors:   University of Maryland, Jain Nishan , Baeder James
Published: October 2024

Current work investigates the sensitivity of DES type hybrid methods toward turbulence length scales and anisotropy of grid. Different length scales available from literature are implemented into a compressible, finite volume GPU accelerated Navier-Stokes solver. A novel length scale is proposed based on the properties of available length scales and the grid requirements in mildly separated flows. Predictive capabilities of RANS and DDES method with the conventional and proposed length scales is assessed by conducting static and dynamic stall simulations on SC1095 and modified VR12 airfoils. Two different grids are used to examine the boundary layer resolving capabilities of the turbulence length scales. RANS based Spalart-Allmaras model and DDES method with conventional length scale predicted excessive eddy viscosity in the boundary layer of flows operating in near-stall regime. Proposed length scale demonstrated good predictive capabilities in mildly separated flows by reducing eddy viscosity levels at the outer region boundary layer. Three dimensional dynamic stall simulations are also conducted on flows over modified VR12 airfoil at moderate reduced frequency. When using proposed length scale, DDES method captured multiple lift peaks before stall and enabled flow to enter deep stall. The predictions agreed well with experimental data and captured cycle-to-cycle variation of integrated aerodynamic quantities. This work further employs specialized treatment to model laminar-turbulent transition and very low Mach number flows.
Parallel Evolutionary Optimization for Rotorcraft Design
Authors:   The Pennsylvania State University, Corle Ethan , Ferguson Kevin , Schmitz Sven
Published: October 2024

A parallel evolutionary strategy is coupled to a comprehensive analysis tool, RCAS, for rotorcraft optimization and design. The evolutionary structure is based on the Covariance Matrix Adaptation Evolution Strategy, CMA-ES, which has proven to be a viable optimization method for rotorcraft problems. Computational efficiency tests show that for a 8 core optimization, the parallel implementation of CMA-ES, pCMA-ES, can result in a significant speedup over the serial counterpart. The pCMA-ES is applied to two active device optimizations problems. First, a previously conducted uniform inflow optimization of an active trailing-edge flap deployment schedule is revisited and optimized using freewake inflow. Next, the optimization of individual blade control, IBC, through an active pitch link is performed. Single harmonic and mixed harmonic inputs are optimized in amplitude and phase with fitness functions defined by rotor performance and hub vibrations. The optimization shows that mixed harmonic inputs can increase the performance gains compared to what single harmonics can accomplish. Furthermore, IBC is shown to be an effective method of controlling specific hub vibrations.
Servo-Flap Rotor Design for High Density Altitude Operation
Authors:   Central Connecticut State University, Wei Fu-Shang
Published: October 2024

It is a unique and challenging task to design a servo-flap main rotor control system that is operational at high density altitudes. At such elevated altitudes, both the main rotor blade and the servo-flap aerodynamics strongly affect helicopter operation. The changes in flap lift alter the aerodynamic pitching moment with respect to the main rotor blade, which results in an interesting blade feathering motion and its required control input. The servo-flap rotor design does not require any pitch link control spring rate. In addition, the blade torsional stiffness and tennis racket moment due to centrifugal force, are almost un-changed by the high altitude air density. The helicopter’s high altitude operation can be achieved through a unique combination of rotor design, servo-flap control, and installed engine power. The servo-flap rotor has a unique ability that allows flap adjustment every time the pilot alters the operating aircraft density altitude by 5,000 feet. This allows the aircraft to retain the same flight characteristics at any altitude that it had at sea level. This unique feature makes the servo-flap rotor one of the best candidates for high altitude flight operation. A new and improved design feature is proposed in this paper. The high altitude actuator control system provides a steady null offset that is simultaneously applied to all flaps. The new actuator signal is introduced in parallel with the basic servo-flap control system. The new hardware is designed to be used within the present control system. This design opens up the autorotation flap control range without impacting servo-flap flight control operation and safety.
JMR Development
Authors:   The Boeing Company, Peterson Greg ,   Sikorsky - a Lockheed Martin Company, Saha Angshuman
Published: October 2024

Sikorsky Aircraft Corporation and The Boeing Company are teamed to execute a series of Technology Investment Agreements (TIA) for the JMR TD (Joint Multi-Role Technology Demonstrator) Program. The capabilities of JMR TD will include combinations of ambient condition hover, speed, range, fuel efficiencies and troop/payload capacities beyond any current rotorcraft. The JMR TD Program addresses the technical risks associated with meeting many of the requirements for the FVL CS3 (Future Vertical Lift Capability Set 3) aircraft. Our team's joint multi-role cooperative efforts provide unrivalled state-of-the-art design and analytical modeling practices leading to advanced vertical flight technologies for the FVL CS3 / JMR TD Program. This paper discusses the interaction of SB>1 DEFIANT™ aircraft technology, configuration and requirements in the design of next generation military rotorcraft, and the Rapid Prototype approach employed by the Sikorsky-Boeing JMR TD Team as we join with the US Government to develop the SB>1 DEFIANTTM Technology Demonstrator Aircraft and associated Mission Systems for the FVL Capability Set 3 Aircraft.
UH-60V: Modernization for Continued Operations
Authors:   AMRDEC Prototype Integration Facility, Shaddix Jonathan , Oden Miranda , Perry Wes
Published: October 2024

The United States (U.S.) Army UH-60L fleet (out of production since 2006), does not meet the current requirement, as identified by the solider in the Operational Requirements Document (ORD) for the recapitalization of the UH-60 Black Hawk Utility Helicopter Fleet. The U.S. Army Aviation and Missile Research, Development and Engineering Center (AMRDEC) team was tasked to update the existing UH-60L analog architecture to a digital infrastructure addressing obsolescence and other life cycle issues related to aging avionics and systems components.
Assessment of Memory Cushions in Aircraft Seating for Injury Mitigation through Dynamic Impact Test
Authors:   Defence Science and Technology Organisation, Wang John ,   Crashlab - Roads and Maritime Service, Nevo Ross
Published: October 2024

Dynamic impact tests were conducted to assess the effectiveness of the Visco-Elastic Polyurethane (VEPU) memory foam seat cushions in mitigating impact to the occupant during an aircraft crash. A FAA specification Hybrid III crash dummy and seats with and without a stroke energy absorbing mechanism were used in the tests. Polyurethane foam (PU) cushions were also tested for comparison. The results with the rigid seat indicated that with 8.3 m/s impact, lumbar spine injury would occur. VEPU cushions reduced the lumbar force by up to 34%. With an impact speed of 6m/s, a VEPU cushion mitigated the impact to the tolerable level, whilst injury would still occur with the PU cushions. The results with the energy absorbing seats showed that with 8.3 m/s impact speed, the seat with over 125 mm (5 inch) stroke length is able to reduce the impact load below the injury threshold. A relatively softer VEPU cushion reduced the lumbar force by over 15% compared with the PU cushions. With a stoke length of 75 mm (3 inch), bottom-out occurred and occupant lumbar spine injury would occur. A relatively higher stiffness VEPU cushion reduced lumbar force by around 20%.
Flight Critical Components: Response to Impact Load
Authors:   Bell Helicopter Textron Inc., Fletcher Timothy , Tho Cheng-Ho , Smith Michael
Published: October 2024

Advances in technology have made rotorcraft more comfortable, more capable, and more complex. With these advances, operators rely more on automated systems to reduce flight crew workload and to elevate safety. Correspondingly, flight-critical systems must remain operational at all times. Mechanical vibration or impact shocks such as bird strikes must not lead to a system failure. The approach for making the Bell 525 as safe as possible uses the guidelines of ARP4754A. The 525 is a commercial entry in the new super medium class of helicopters, and is the only commercial helicopter with fly-by-wire (FBW) flight control technology with state-of-the-art avionics. Safety requirements and certification regulations mandate the ability for continued safe flight following a bird strike incident. Improvements in computer simulation capabilities enable relating mechanical shock qualification tests with in-flight impact threats.