Estimation of Wind Tunnel Corrections Using Potential Models

The evaluation of the tunnel correction remains an actual problem, especially for the effect of tunnel walls. Even if the experimental campaign meets the basic similitude criteria (Mach, Reynolds etc.), the wall effect on the measured data is always present. Consequently, the flow correction due the limited by walls must be evaluated. Solid wall corrections refer to the aerodynamic interference between the experimental model and the walls of the wind tunnel. This interaction affects the measured forces and implicitly the angle of attack. Usually, these effects are introduced through semi-empirical correction factors which change the global measured forces. The present paper refers to the mathematical and numerical modeling of aerodynamic interferences between the experimental model and the solid walls based on the potential flow model. The main goal is to asses a method allowing an estimate of the corrections for each configuration with a minimum computational resource

Using genetic algorithms to optimize airfoils in incompressible regime

Aerodynamic optimization is a very actual problem in aircraft design and airfoils are basic two-dimensional shape forming cross sections of wings. Traditionally, the airfoil geometry if defined by a very large number of coordinates. Nowadays, in order to simplify the optimization, the airfoil geometry is approximated by a parametrization, which enables to reduce the number of needed parameters to as few as possible, while effectively controlling the major aerodynamic features. The present work has been done on the Class-Shape function Transformation method (CST) [1, 2]. Also, the paper introduces the concept of Genetic Algorithm (GA) to optimize a NACA airfoil for specific conditions. A Matlab program has been developed to implement CS into the Global Optimization Toolkit. The pressure distribution lift and drag coefficients of the airfoil geometries have been calculated using two programs. The first one is an in-house code based on the Hess-Smith [3] panel technique and on the boundary layer integral equations, while the second is an XFOIL program. The optimized airfoil has improved aerodynamic characteristics as compared to the original one. The optimized airfoil is validated using the Ansys-Fluent commercial code

Identification of roll damping coefficient using the free rotation method

The free rotation method represents the simplest method for roll damping coefficient identification in experimental aerodynamics. To apply this method, it is necessary to spin the model to a desired angular velocity and then release the model to spin freely under flow conditions, recording the variation in time of the model’s rolling rate. Thus, applying the logarithmic decrement formula at any roll rate between near zero and the desired angular velocity, the roll damping moment will be calculated. This paper presents the application of the free rotation method on raw data obtained for different Mach numbers and incidences, considering different regression functions, time windows and their implications. Last but not least, the necessary correction methods and their impact on the results are presented

Coherent solutions to roll damping derivatives evaluation for a generic rocket model

This paper presents a coherent approach to evaluate the roll damping derivatives for the standard Basic Finner Model. The study compares and analyses the results obtained through a range of techniques, including experimental testing, numerical simulations and semi-empirical models. The study aims to evaluate the reliability and accuracy of these methods and to identify the factors that contribute to their sensitivity. The paper concludes by summarizing the findings of the study and discussing the implications of the results for the design and operation of rockets. The experimental and numerical analysis used in this study provides a robust and comprehensive evaluation of the roll damping coefficient

Development of Jets rig dedicated for an Active Launch Escape Abort System Wind Tunnel Model

The development of space launch systems requires rigorous testing and validation of safety mechanisms to ensure the protection of human life and mission-critical assets. One such safety mechanism is the Active Launch Escape/Abort System (ALEAS), designed to swiftly extract crew and spacecraft from a malfunctioning launch vehicle. To evaluate the performance of ALEAS, wind tunnel testing is indispensable. This paper presents the development of a specialized Jets Rig tailored for wind tunnel testing of an ALEAS model. The primary objectives of this research activity include the design, construction, and validation of a Jets Rig that can accurately simulate the propulsion dynamics of an ALEAS system within a wind tunnel environment. The Jets Rig incorporates a special instrumentation and control systems to replicate the complex operational conditions experienced during a launch abort scenario. By achieving this, it enables a comprehensive assessment of ALEAS performance, including thrust duration and plume interaction effects, among others. Key aspects of this study encompass the aerodynamic and structural considerations involved in designing the Jets Rig, the integration of high-fidelity sensors and data acquisition systems, and the development of advanced computational models for predictive analysis. Additionally, the research explores the challenges and solutions associated with the scalability of the Jets Rig to accommodate varying scales of ALEAS models. The findings from this project hold significant implications for advancing the safety and reliability of crewed space missions. A comprehensive understanding of ALEAS performance in a wind tunnel setting allows for the refinement of design parameters, algorithms, and the enhancement of abort system efficiency. Ultimately, the successful development of this dedicated Jets Rig contributes to the broader mission of ensuring the safe exploration of space and the protection of human life in the challenging and dynamic environment of space launch