Proposal of a methodology for the design of the installation of turrets on aircrafts – the approach on the aerodynamic influences

The present work has its origin on the necessity of enabling a design certified company, or DOA (Design Organization Approval), to perform a modification; this modification is the installation of EO/IR (Electro-optical infrared) sensors on aircrafts. The subject of interest in this dissertation lies on the aerodynamic impact of the modification on the aircraft. The primary purpose of the present thesis is the creation of a methodology that regards the design stage of the modification. This methodology serves as guidance to the DOA design team that is assigned to the design of the modification. The methodology includes a recommendation to the certification of the modification; it contains a method intended to decide the location of the installation of the sensors on the aircraft; it also comprises of a design structure specifically adapted to the modification in study. Regarding the aerodynamic impact, it is studied the aerodynamic analysis’ tools, which allows one to relate the different stages of design to the most suited tools to each stage. A case study is performed with the purpose of not only validating the methodology which was created but also to giving a first approach to the preliminary design of the modification. As example, there are used the Lockheed Martin C-130 aircraft and the FLIR Star Safire III sensor

Patient-specific design of the right ventricle to pulmonary artery conduit via computational analysis

Cardiovascular prostheses are routinely used in surgical procedures to address congenital malformations, for example establishing a pathway from the right ventricle to the pulmonary arteries (RV-PA) in pulmonary atresia and truncus arteriosus. Currently available options are fixed size and have limited durability. Hence, multiple re-operations are required to match the patients’ growth and address structural deterioration of the conduit. Moreover, the pre-set shape of these implants increases the complexity of operation to accommodate patient specific anatomy. The goal of the research group is to address these limitations by 3D printing geometrically customised implants with growth capacity. In this study, patient-specific geometrical models of the heart were constructed by segmenting MRI data of patients using Mimics inPrint 2.0. Computational Fluid Dynamics (CFD) analysis was performed, using ANSYS CFX, to design customised geometries with better haemodynamic performance. CFD simulations showed that customisation of a replacement RV-PA conduit can improve its performance. For instance, mechanical energy dissipation and wall shear stress can be significantly reduced. Finite Element modelling also allowed prediction of the suitable thickness of a synthetic material to replicate the behaviour of pulmonary artery wall under arterial pressures. Hence, eliminating costly and time-consuming experiments based on trial-and-error. In conclusion, it is shown that patient-specific design is feasible, and these designs are likely to improve the flow dynamics of the RV-PA connection. Modelling also provides information for optimisation of biomaterial. In time, 3D printing a customised implant may simplify replacement procedures and potentially reduce the number of operations required over a life time, bringing substantial improvements in quality of life to the patient

Micro-Channel Arrays by Two Photon Lithography for Cell Migration Studies

Metastasis is a dynamic process in which cancer cells begin to move. Understanding how these cells acquire increased motility is a stimulating and necessary goal. The goal of this thesis is to produce a microfluidic device that allows the study of chemotaxis of Neuroblastoma cells and the device was fabricated using an innovative two-photon polymerization (2PP) technology.openEmbargo temporaneo per motivi di segretezza e/o di proprietà dei risultati e/o informazioni sensibil

An Integrated Flow-Curing Model for Predicting Residual Stresses in Textile Composites

Fiber-reinforced composites have been widely employed in structural applications due to their high stiffness-to-weight ratio and easily-tailored mechanical properties. However, manufacturing of these lightweight materials involves an infusion and curing process, and flow-induced defects and residual stresses can easily occur, which can compromise the mechanical performance of the composite structures. The purpose of this work is to develop an integrated flow-curing processing model to accurately predict the resin flow front and the residual stresses in the Liquid Composite Molding (LCM) process. In the infusion model, the fiber fabrics are treated as a homogeneous and porous material, and the resin flow movement is governed by the Navier-Stokes equations. The resin flow can be solved using the Volume of Fluid (VOF) method. Due to the pressure equilibrium, the resin flow movement and the compaction of the fiber preform are two-way coupled, and the coupling between the flow and compaction models can be captured in the proposed model. After the infusion simulation, the residual stresses are predicted through a curing model. Since the thermal and chemical strains are major contributing factors to the residual stresses, the temperature and cure progression inside the composite are first predicted through a thermal-chemical analysis. Based on the predicted temperature and cure progression, the residual stress development can be captured through a thermo-viscoelastic model. Based on the elastic moduli of the fiber and viscoelastic properties of the resin, the effective relaxation moduli of the composite can be predicted through the correspondence principle and micromechanics models. The effective composite properties are then included in a 3D anisotropic viscoelastic constitutive law, and the differential form of the constitutive law is developed for numerical implementation to improve the computational efficiency. The accuracy of the processing model is assessed by comparing the simulation results against experiments through a set of benchmark examples. The proposed coupled flow-curing processing model is physics-based and experimentally-validated, which can be employed to understand the variability in composite manufacturing and identify the root causes of processing-induced defects. The integrated model shows great promise as a modeling toolkit to guide the design of optimal manufacturing procedures with minimized defects

Thirteenth Workshop for Computational Fluid Dynamic Applications in Rocket Propulsion and Launch Vehicle Technology

This conference publication includes various abstracts and presentations given at the 13th Workshop for Computational Fluid Dynamic Applications in Rocket Propulsion and Launch Vehicle Technology held at the George C. Marshall Space Flight Center April 25-27 1995. The purpose of the workshop was to discuss experimental and computational fluid dynamic activities in rocket propulsion and launch vehicles. The workshop was an open meeting for government, industry, and academia. A broad number of topics were discussed including computational fluid dynamic methodology, liquid and solid rocket propulsion, turbomachinery, combustion, heat transfer, and grid generation

Titan I Propulsion System Modeling and Possible Performance Improvements

This thesis features the Titan I propulsion systems and offers data-supported suggestions for improvements to increase performance. The original propulsion systems were modeled both graphically in CAD and via equations. Due to the limited availability of published information, it was necessary to create a more detailed, secondary set of models. Various engineering equations--pertinent to rocket engine design--were implemented in order to generate the desired extra detail. This study describes how these new models were then imported into the ESI CFD Suite. Various parameters are applied to these imported models as inputs that include, for example, bi-propellant combinations, pressure, temperatures, and mass flow rates. The results were then processed with ESI VIEW, which is visualization software. The output files were analyzed for forces in the nozzle, and various results were generated, including sea level thrust and ISP. Experimental data are provided to compare the original engine configuration models to the derivative suggested improvement models

Development And Validation Of A Hypersonic Vehicle Design Tool Based On Waverider Design Technique

Methodologies required for the creation of an aircraft design tool capable of generating practical hypersonic vehicle configurations based on the waverider design concept were developed and validated. The design space for these configurations was formulated by using an algorithm that coupled the directional derivatives to the conservation laws to produce flow fields in the form of organized sets of post-shock stream-surfaces. This design space is used to construct ideal waverider configurations with a sharp leading edge. A carving methodology was also developed to transform the idealized waverider geometry into practical aircraft configurations with blunted leading edges for hypersonic mission applications. Further, methodologies, based on both empirical and analytical relations, were developed and implemented to evaluate the resulting aerothermo-dynamic performance of the resulting hypersonic aircraft configuration. In this dissertation, methodologies to determine the local pressure, skin-friction and heat flux were also developed, implemented and validated

Best practice guidelines in external aerodynamics CFD: applied to unmanned aerial vehicles at cruise conditions

Alferes-Aluno ENGAER 136867-C Ricardo José Cabral Veríssimo. Supervisor: Dr. Nelson Pereira Caetano Marques; Co-supervisors: Major ENGEL João Manuel Moreira Simões. Capitão ENGAER Ana Sofia Andrês dos Reis Lesiário Examination Committee: Chairperson: MGen PILAV Joaquim Manuel Nunes Borrego; Supervisor: Dr. Nelson Pereira Caetano Marques; Co-supervisors: Major ENGEL João Manuel Moreira Simões; Capitão ENGAER Ana Sofia Andrês dos Reis Lesiário; Member of the Committee: Major ENGAER Carlos Pereira da SilvaO presente trabalho visa o estabelecimento de uma metodologia para a caracterização aerodinâmica de veículos aéreos nâo-tripulados (VANT) em condições de cruzeiro no âmbito de projectos de investigação na Força Aérea Portuguesa. Este estudo foca-se no preparação de modelos baseados na mecânica de fluidos computacional (CFD) e de testes em túnel de vento e voo que permitam correlação e validação cruzada de resultados. O caso de estudo é um VANT de classe I que opera a baixas velocidades subsónicas. Informação relativa a esta aplicação específica deste tipo de estudos é limitada na comunidade científica e, dado o crescente interesse em tecnologia ligada a VANTs, considera-se altamente relevante para a industria aeroespacial tanto no sector civil como militar. Casos de validação bidimensionais (perfil alar) a tridimensionais (asa finita) são apresentados por forma a aferir a precisão dos resultados e as limitações dos métodos utilizados comparativamente a dados publicados. As simulaçães foram implementadas em Star-CCM+ e testes em túnel de vento foram executados numa secção de teste aberta com meio-modelos, equipados com tomadas de pressão e produzidos por impressão 3D, para escoamentos entre os números de Reynolds de 3:0 105 e 4:1 105. Testes de visualizacção de escoamentos foram efectuados por forma a obter informacção adicional para uma validacção qualitativa. Os testes de voo introduzem equipamentos desenvolvidos específicamente para pequenas plataformas aéreas não tripuladas a partir de componentes electrónicos de baixo custo. Os resultados computacionais correlacionam-se favoravelmente com dados publicados e estão em excelente acordo com os resultados dos testes de visualização de escoamentos. As leituras de pressão nas tomadas de pressão em túnel de vento correlacionam-se bem com os resultados experimentais mas não foram bem sucedidas em voo. As forças aerodinâmicas medidas em túnel de vento não validam as previsões computacionais mas aparentam subestimar sustentação e sobrestimar a resistência aerodinâmica consistentemente.The purpose of this paper is to establish a methodology for the aerodynamic characterization of unmanned aerial vehicles at cruise conditions in the Portuguese Air Force, focusing on the set-up of computational fluid dynamics models and both wind tunnel and flight testing experimental procedures that warrant correlation and cross-validation of results. The case study is a Class I UAV with a twin boom pusher prop configuration that operates at low subsonic speeds. Information for this specific application was found to be limited in the scientific literature and, given the increasing interest in unmanned aerial vehicle technology, it is considered highly relevant for the aerospace industry on civil and military sectors alike. 2-Dimensional (airfoil) and 3-dimensional (finite wing) validation test cases are presented in order to access the accuracy of the results and limitations of the employed methods against published data. Numerical simulations were implemented with commercial software Star-CCM+ and wind tunnel tests were executed in an open test section with a reflection plane and 3D printed semi-span models with pressure taps, for Reynolds numbers ranging from 3:0 105 to 4:1 105. Flow visualization wind tunnel tests with china-clay were performed in order to collect additional qualitative experimental validation data. Flight testing introduces several proof-of-concept equipments featuring low-cost sensors for unmanned flight data acquisition in small platforms. The computational results correlate favourably with the available reference data and are in excellent agreement with the experimental flow visualization results. Pressure tap measurements from wind tunnel tests compare well against computational results but were unsuccessful in flight. Wind tunnel force coefficient results do not validate the computational predictions, but appear to consistently under-predict lift and over-predict drag.N/