The Beginner's Guide to Wind Tunnels with TunnelSim and TunnelSys

The Beginner's Guide to Wind Tunnels is a Web-based, on-line textbook that explains and demonstrates the history, physics, and mathematics involved with wind tunnels and wind tunnel testing. The Web site contains several interactive computer programs to demonstrate scientific principles. TunnelSim is an interactive, educational computer program that demonstrates basic wind tunnel design and operation. TunnelSim is a Java (Sun Microsystems Inc.) applet that solves the continuity and Bernoulli equations to determine the velocity and pressure throughout a tunnel design. TunnelSys is a group of Java applications that mimic wind tunnel testing techniques. Using TunnelSys, a team of students designs, tests, and post-processes the data for a virtual, low speed, and aircraft wing

Advanced Visualization of Experimental Data in Real Time Using LiveView3D

LiveView3D is a software application that imports and displays a variety of wind tunnel derived data in an interactive virtual environment in real time. LiveView3D combines the use of streaming video fed into a three-dimensional virtual representation of the test configuration with networked communications to the test facility Data Acquisition System (DAS). This unified approach to real time data visualization provides a unique opportunity to comprehend very large sets of diverse forms of data in a real time situation, as well as in post-test analysis. This paper describes how LiveView3D has been implemented to visualize diverse forms of aerodynamic data gathered during wind tunnel experiments, most notably at the NASA Langley Research Center Unitary Plan Wind Tunnel (UPWT). Planned future developments of the LiveView3D system are also addressed

Wind Load Design of a Triangular Shaped Building Using finite Element Analysis

This major qualifying project investigates wind loading and structural design of a triangular-shaped 5-story building in San Francisco. Finite Element Method (FEM) software, ANSYS 19.1 is adopted to create a virtual wind tunnel test in accordance with ASCE 7-16 and ASCE 49-12. This project focuses on simulating two types of wind-tunnel test, Rigid Pressure Model Technique and High-Frequency Base-Balance (Time-Domain Analysis) Technique. Of those two techniques, the final structural design in based on the Rigid Pressure Model Technique

ESWIRP: European Strategic Wind tunnels Improved Research Potential program overview

International audience“European Strategic Wind tunnel Improved Research Potential” ESWIRP was a project in the EU 7th Framework Program (FP7—Grant agreement no: FP7-227816), which was aiming at improving the performance capabilities of three strategic wind tunnels in Europe, by strengthening the cooperation between these wind tunnels in a new consortium. The research consortium members are Office National d’Etudes et de Recherches Aérospatiales (operating the S1MA as its largest sonic wind tunnel), German–Dutch wind tunnels [operating the large low-speed facility (LLF) as its largest low-speed wind tunnel], and European transonic wind tunnel (ETW) (operating its cryogenic wind tunnel). Together, these wind tunnels cover a wide range of experimental capabilities of relevance to civil aviation and aeronautical research in general. The project started in October 2009 for a period of 5 years. The European financial contribution was €7.2 million. The project consist of two major parts: (1) improvements to the testing infrastructure; and (2) the provision of wind tunnel access to research groups which do not usually have the means to access such large-scale test facilities. These topics also involved public dissemination and information activities. Although the tunnels covered in this project are of a complementary nature, the infrastructure activities were joined together, by a common representation of, and approach to, the tunnel performance characteristics. To this end, a generic model of a virtual wind tunnel was developed, enabling operators to assess the effect of the control parameters upon the testing conditions. The final aim of all participants was to provide the user community with an improved set of capabilities to test their innovative ideas. To provide better access to these three major wind tunnels, mainly research groups from European universities were contacted. The approach taken has included maximum transparency of the process and support of the researchers by the organizations responsible for the tunnels. In addition, when possible, we encouraged research groups to work together, to obtain the full benefit of economies of scale in research projects

Master of Science

thesisThis thesis discusses the development of an olfactory display for the University of Utah TreadPort Virtual Environment (UUTVE). The goal of the UUTVE is to create a virtual environment that is as life like as possible by communicating to the user as many of the sensations felt in moving around in real the world as possible, while staying within the confines of the virtual environment's workspace. The UUTVE has a visual display, auditory display, a locomotion interface and wind display. With the wind display, it is possible to create an effective olfactory display that does not have some of the limitations associated with many of the current olfactory displays. The inclusion of olfactory information in virtual environments is becoming increasingly common as the effects of including an olfactory display show an increase in user presence. The development of the olfactory display for the UUTVE includes the following components: the physical apparatus for injecting scent particles into the air stream, the development of a Computational Fluid Dynamics (CFD) model with which to control the concentration of scent being sensed by the user, and user studies to verify the model and show as proof of concept that the wind tunnel can be used to create an olfactory display. The physical apparatus of the display consists of air atomizing nozzles, solenoids for controlling when the scents are released, containers for holding the scents and a pressurized air tank used to provide the required air to make the nozzles work. CFD is used model the wind flow through the TPAWT. The model of the wind flow is used to simulate how particles advect in the wind tunnel. These particle dispersion simulations are then used to create a piecewise model that is able to predict the scent's concentration behavior as the odor flows through the wind tunnel. The user studies show that the scent delivery system is able to display an odor to a person standing in the TPAWT. The studies also provided a way to measure the time it takes for a person to recognize an odor after it has been released into the air stream, and also the time it takes for a user to recognize that the odor is no longer present

Bicycle Wheel Aerodynamics Predictions Using CFD: Efficiency Using Blade Element Theory

The cycling industry has long relied on expensive wind tunnel testing when designing aerodynamic products, particularly in the context of wheels which account for 10 to 15 percent of a cyclist’s total aerodynamic drag. With the recent advent of computational fluid dynamics, the industry now has an economical tool to supplement the wheel design process; however, the complex nature of rotating spoked wheels requires high resolution meshes to model at acceptable fidelity. This research investigates an alternative CFD method that lowers the computational cost of modeling aerodynamic bicycle wheels by modeling spokes using blade element momentum virtual disks. Two CFD models of a HED Trispoke wheel, one with resolved spokes (physical mesh) and one with modeled spokes (virtual disk), are compared to existing CFD and wind tunnel drag coefficient data at various headwind speeds and angles. Preliminary data shows good agreement

Evaluation of the dynamic core of the PALM model system 6.0 in a neutrally stratified urban environment: comparison between LES and wind-tunnel experiments

We demonstrate the capability of the PALM model system version 6.0 to simulate neutrally stratified urban boundary layers. Our simulation uses the real-world building configuration of the HafenCity area in Hamburg, Germany. Using PALM's virtual measurement module, we compare simulation results to wind-tunnel measurements of a downscaled replica of the study area. Wind-tunnel measurements of mean wind speed agree within 5 % on average while the wind direction deviates by approximately 4∘. Turbulence statistics similarly agree. However, larger differences between measurements and simulation arise in the vicinity of surfaces where building geometry is insufficiently resolved. We discuss how to minimize these differences by improving the grid layout and give tips for setup preparation. Also, we discuss how existing and upcoming features of PALM like the grid nesting and immersed boundary condition help improve the simulation results.publishedVersio

Evaluation of the dynamic core of the PALM model system 6.0 in a neutrally stratified urban environment: Comparison between les and wind-tunnel experiments

We demonstrate the capability of the PALM model system version 6.0 to simulate neutrally stratified urban boundary layers. Our simulation uses the real-world building configuration of the HafenCity area in Hamburg, Germany. Using PALM's virtual measurement module, we compare simulation results to wind-tunnel measurements of a downscaled replica of the study area. Wind-tunnel measurements of mean wind speed agree within 5% on average while the wind direction deviates by approximately 4 °. Turbulence statistics similarly agree. However, larger differences between measurements and simulation arise in the vicinity of surfaces where building geometry is insufficiently resolved. We discuss how to minimize these differences by improving the grid layout and give tips for setup preparation. Also, we discuss how existing and upcoming features of PALM like the grid nesting and immersed boundary condition help improve the simulation results. © 2021 Tobias Gronemeier et al

Characterisation and airborne deployment of a new counterflow virtual impactor inlet

A new counterflow virtual impactor (CVI) inlet is introduced with details of its design, laboratory characterisation tests and deployment on an aircraft during the 2011 Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE). The CVI inlet addresses three key issues in previous designs; in particular, the inlet operates with: (i) negligible organic contamination; (ii) a significant sample flow rate to downstream instruments (∼15 l min^(−1)) that reduces the need for dilution; and (iii) a high level of accessibility to the probe interior for cleaning. Wind tunnel experiments characterised the cut size of sampled droplets and the particle size-dependent transmission efficiency in various parts of the probe. For a range of counter-flow rates and air velocities, the measured cut size was between 8.7–13.1 μm. The mean percentage error between cut size measurements and predictions from aerodynamic drag theory is 1.7%. The CVI was deployed on the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter for thirty flights during E-PEACE to study aerosol-cloud-radiation interactions off the central coast of California in July and August 2011. Results are reported to assess the performance of the inlet including comparisons of particle number concentration downstream of the CVI and cloud drop number concentration measured by two independent aircraft probes. Measurements downstream of the CVI are also examined from one representative case flight coordinated with shipboard-emitted smoke that was intercepted in cloud by the Twin Otter

Control of long-range correlations in turbulence

The character of turbulence depends on where it develops. Turbulence near boundaries, for instance, is different than in a free stream. To elucidate the differences between flows, it is instructive to vary the structure of turbulence systematically, but there are few ways of stirring turbulence that make this possible. In other words, an experiment typically examines either a boundary layer or a free stream, say, and the structure of the turbulence is fixed by the geometry of the experiment. We introduce a new active grid with many more degrees of freedom than previous active grids. The additional degrees of freedom make it possible to control various properties of the turbulence. We show how long-range correlations in the turbulent velocity fluctuations can be shaped by changing the way the active grid moves. Specifically, we show how not only the correlation length but also the detailed shape of the correlation function depends on the correlations imposed in the motions of the grid. Until now, large-scale structure had not been adjustable in experiments. This new capability makes possible new systematic investigations into turbulence dissipation and dispersion, for example, and perhaps in flows that mimic features of boundary layers, free streams, and flows of intermediate character.Comment: This paper has been accepted to Experiments in Fluids. 25 pages, 10 figure