Search results for "Aerodynamics"

Aerodynamics of an isolated ski jumping ski

2019

A single isolated ski was suspended from a six-component wind tunnel balance and three angles, the angle of attack, the yaw angle and the edge angle were adjustable during the test. Increasing yaw angle from 0 to 15° increased the lift coefficient CL from 0.42 to 0.90 at edge angle 0° and from 0.70 to 0.87 at edge angle 10°, respectively. Increasing yaw angle also increased the sensitivity of the ski to changes in edge angle, i.e., increasing the edge angle (20°–45°) decreased the CL and the ratio $$C_{L}^{2}/{C_D}$$ with large yaw angles. However, to maximize the lift-to-drag ratio with a typical angle of attack of 30° in ski jumping, it may be reasonable to have an edge angle of 5°–10° on…

Beyond robust design: an example of synergy between statistics and advanced engineering design

2002

Higher efficiency and effectiveness of Research & Development phases can be attained using advanced statistical methodologies. In this work statistical methodologies are combined with a deterministic approach to engineering design. In order to show the potentiality of such integration, a simple but effective example is presented. It concerns the problem of optimising the performance of a paper helicopter. The desgin of this simple device is not new in quality engineering literature and has been mainly used for educational purposes. Taking full advantage of fundamental engineering knowledge, an aerodynamic model is originally formulated in order to describe the fligh of the helicopter. S…

Wavelet-Based Optimal Control of a Wind Turbine System: A Computational Approach

2011

This paper deals with a computational optimization approach to the problem of state-feedback control design for a wind turbine system. The first step of the study is to develop a reduced order model for the system by considering the most important physical phenomena of aerodynamics and structural dynamics. Moreover, the behavior of the system can be influenced by the coupled dynamics between the tower motions and the blade pitch and turbine speed which can cause instabilities in the control loops in the worst case. By using a suitable wavelet funcation, called Haar functions, a recursive computational procedure is established for finding the system dynamics approximately by solving only alg…

Implementation of an aerodynamic lens for TRIGA-SPEC

2016

Abstract We report on the optimization of the gas-jet system employed to couple the TRIGA-SPEC experiment to the research reactor TRIGA Mainz. CdI2 aerosol particles suspended in N2 as carrier gas are used for an effective transport of fission products from neutron induced 235 U fission from the target chamber to a surface ion source. Operating conditions of the gas-jet were modified to enable the implementation of an aerodynamic lens, fitting into the limited space available in front of the ion source. The lens boosts the gas-jet efficiency by a factor of 4–10. The characterization of the gas-jet system as well as the design of the aerodynamic lens and efficiency studies are presented and …

A multi-technique simultaneous approach for the design of a sailing yacht

2015

In this paper, most significant steps involved during the whole process of designing a sailing yacht are outlined. In particular, a novel simultaneous approach has been proposed to optimize the design process of a sailing yacht. Analytical resistance prediction models are simultaneously used with CAD systems and computational fluid dynamics tools to find, in the more effective way, the best solution for the chosen design conditions. As a general rule, in fact, once the target point has been decided, task of the designer is the definition of those systems of aerodynamic and hydrodynamic forces that are in equilibrium when the boat sails at its target. Unfortunately, a multi-purpose yacht doe…

2020

The complex surface geometries of hailstones affect their fall behavior, fall speeds, and growth. Systematic experimental investigations on the influence of the number and length of lobes on the fall velocity and the drag coefficient of hailstones were performed in the Mainz vertical wind tunnel to provide relationships for use in numerical models. For this purpose, 3D prints of four artificial lobed hailstone models as well as spheres were used. The derived drag coefficients show no dependency in the Reynolds number in the range between 25,000 and 85,000. Further, the drag coefficients were found to increase with increasing length of lobes. All lobed hailstones show higher or similar drag …

Physical model, theoretical aspects and applications of the flight of a ball in the atmosphere. Part I: Modelling of forces and torque, and theoretic…

1991

A model of the forces and the torque operating on a ball that is flying with rotation in the atmosphere of the Earth, and the resulting system of ordinary differential equations, are derived from mechanics and aerodynamics. The system of equations allows the theoretical aspects of the flight of a ball, such as the boundedness of its kinetic energy, the curvature of the orbit or the velocity function, to be investigated using certain transformations of the variables. The solutions of the corresponding ordinary or boundary value problems, computed numerically, are used to treat certain tasks in international ball games, for example, the maximum and minimum velocities of a volleyball service.

Shape design optimization in 2D aerodynamics using Genetic Algorithms on parallel computers

1996

Publisher Summary This chapter presents two Shape Optimization problems for two dimensional airfoil designs. The first one is a reconstruction problem for an airfoil when the velocity of the flow is known on the surface of airfoil. The second problem is to minimize the shock drag of an airfoil at transonic regime. The flow is modeled by the full potential equations. The discretization of the state equation is done using the finite element method and the resulting non-linear system of equations is solved by using a multi-grid method. The non-linear minimization process corresponding to the shape optimization problems are solved by a parallel implementation of a genetic algorithm (GA). Some n…

Analysis Based Optimization of Human Powered Vehicle Body

2015

The human powered vehicle market is not only a larger market per unit than the automotive market, but it is one in growth. The main product of this market is the classical bicycle, which is familiar around the globe, but mainly in the urban environment. The bicycle, which in this paper will be considered a human powered vehicle, is slowly gaining ground in the field of urban transportation solutions. This paper analyzes the possibility of optimizing the body of a human powered vehicle recumbent tricycle through continuous fluid dynamics. The vehicle is already designed and built, and is fully functional. The body of the vehicle comes as a necessity to give the operator protection from the e…

Investigation of superspreading COVID-19 outbreak events in meat and poultry processing plants in Germany: A cross-sectional study.

2020

Since May 2020, several COVID-19 outbreaks have occurred in the German meat industry despite various protective measures, and temperature and ventilation conditions were considered as possible high-risk factors. This cross-sectional study examined meat and poultry plants to examine possible risk factors. Companies completed a self-administered questionnaire on the work environment and protective measures taken to prevent SARS-CoV-2 infection. Multivariable logistic regression analysis adjusted for the possibility to distance at least 1.5 meters, break rules, and employment status was performed to identify risk factors associated with COVID-19 cases. Twenty-two meat and poultry plants with 1…