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Book Study Implementation and Validation of a Wall Pressure signature Blockage Correction Method for the Wind Tunnel of the ESEIAAT Aerospace Laboratory

Download or read book Study Implementation and Validation of a Wall Pressure signature Blockage Correction Method for the Wind Tunnel of the ESEIAAT Aerospace Laboratory written by Francisco Javier Faus Dexeus and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study is the development, implementation and validation of a blockage correction method based on wall pressure signatures. The work involves the design and construction of the required wind tunnel instrumentation and models, as well as the implementation of a computer program to process the wind tunnel data. The program is able to correct dynamic pressure and drag measurements, even for lifting models. In this work, the wall pressure signature is measured in a manual manner by means of a multi-tube manometer which has been designed and built for this purpose. Validation experiments have been also designed and performed using cylinders. A brief uncertainty study of the results is also presented. The program has been developed using MATLAB software. It is based on the iterative version of the wall pressure signature method originally developed by Hackett et al. The program is capable of obtaining a reconstruction of the wall pressure distribution along the wind tunnel walls. From this reconstruction, the required corrections for the dynamic pressure inside the tunnel, the measured aerodynamic resistance and the drag coefficient are obtained. The developed program has been validated experimentally. Experiments on cylinders of different diameter have been carried out to observe the change in corrections for different blockage ratios (relation between model frontal area and tunnel cross-sectional area). Velocity in each experiment has been adjusted in order to maintain a constant Reynolds number between different diameter cylinders. An uncertainty analysis of the results has been performed through the Monte Carlo method to obtain an approximate error for the corrections. The results obtained have been consistent for blockage ratios below 15% and coherent with the descriptions from Hackett. However, the measurements present some discrepancy with published data in the literature. For example, experimental force measures (before correction) obtained have been higher than predicted by other experiments (specially for low blockages). This can be due to some bias in the measurements (produced by misalignment) or simply due to the uncertainty observed in the experiment. Results of the uncertainty analysis have shown that the errors in drag coefficient are considerable for the magnitude of forces measured in the experiment, but reduce significantly as the measured force increases. It has also been observed that a large part of the uncertainty in the results is due to the uncertainty in the measurements of aerodynamic drag.

Book Wall Pressure Signature

Download or read book Wall Pressure Signature written by J. G. Proctor and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Wind Tunnel Wall Correction

Download or read book Wind Tunnel Wall Correction written by B. F. R. Ewald and published by . This book was released on 1998 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report was compiled by an international team of wind tunnel wall correction experts. It presents the present state of the art in wind tunnel wall corrections with a special emphasis given to the description of modern wall correction methods based on Computational Fluid Dynamics. This AGARDograph was planned by the AGARD Fluid Dynamics Panel to be a modern sequel of the successful AGARDograph 109 "Subsonic Wind Tunnel Wall Corrections", which was published in 1966. AGARDogaph 109 is still valid and continues to be used to provide wall corrections in many wind tunnels. Nevertheless, in the thirty two years since the publication of AGARDograph 109, much work has been done on the subject, and the influence of the new tool of numerical fluid dynamics was so strong, that a sequel to AGARDograph 109 was considered to be necessary.

Book Study of the Integration of Wind Tunnel and Computational Methods for Aerodynamic Configurations

Download or read book Study of the Integration of Wind Tunnel and Computational Methods for Aerodynamic Configurations written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-11-12 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was conducted to determine the effectiveness of using a low-order panel code to estimate wind tunnel wall corrections. The corrections were found by two computations. The first computation included the test model and the surrounding wind tunnel walls, while in the second computation the wind tunnel walls were removed. The difference between the force and moment coefficients obtained by comparing these two cases allowed the determination of the wall corrections. The technique was verified by matching the test-section, wall-pressure signature from a wind tunnel test with the signature predicted by the panel code. To prove the viability of the technique, two cases were considered. The first was a two-dimensional high-lift wing with a flap that was tested in the 7- by 10-foot wind tunnel at NASA Ames Research Center. The second was a 1/32-scale model of the F/A-18 aircraft which was tested in the low-speed wind tunnel at San Diego State University. The panel code used was PMARC (Panel Method Ames Research Center). Results of this study indicate that the proposed wind tunnel wall correction method is comparable to other methods and that it also inherently includes the corrections due to model blockage and wing lift. Browne, Lindsey E. and Ashby, Dale L. Ames Research Center...

Book Rectangular wind tunnel Blocking Corrections Using the Velocity ratio Method

Download or read book Rectangular wind tunnel Blocking Corrections Using the Velocity ratio Method written by Rudolph W. Hensel and published by . This book was released on 1951 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt: Calculations of the ratios of the velocity increments at test bodies to those at the tunnel walls caused by the solid blocking of these bodies within the walls of a closed rectangular wind tunnel are presented. The boides treated include two-dimensional airfoils; small bodies of revolution; straight, untapered, finite-span wings of varying span; and swept, untapered, finite-span wings of varying span. It is shown that, after wake blocking effects have been removed , the present method furnishes semiempirical blocking corrections for most wind-tunnel models and their components. The test section proportions of the Southern California Cooperative Wind Tunnel at CIT (ratio of height to width equal to 1/square root of 2) are used in the calculations.

Book Research on Adaptive Wall Wind Tunnels

Download or read book Research on Adaptive Wall Wind Tunnels written by Robert J. Vidal and published by . This book was released on 1978 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research was to investigate the utility of the Calspan self-correcting wind tunnel for minimizing or eliminating wall interference effects in two-dimensional transonic flows when shock waves from the test model extend to the tunnel walls. This report summarizes the experimental research performed with two-dimensional airfoils in the Calspan self-correcting wind tunnel and the theoretical research accomplished in support of the experiments. The experiments were performed with airfoil models having 4% and 6% solid blockage. The initial experiments with the 6%-blockage model were devoted to determining a practical mode of operation when shock waves from the model extend to the wall. The most practical model is to use wall control to obtain the desired distribution of longitudinal velocity components for subcritical walls. The Mach number is then increased and the wall control is readjusted, sequentially, until the desired test condition is achieved. At the high Mach numbers of interest, however, the available wall control was limited locally, and tunnel system changes were required. A method is reported for analyzing self-correcting wind tunnels with porous walls.

Book Direct Validation of the Wall Interference Correction System of the Ames 11 Foot Transonic Wind Tunnel

Download or read book Direct Validation of the Wall Interference Correction System of the Ames 11 Foot Transonic Wind Tunnel written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-31 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Data from the test of a large semispan model was used to perform a direct validation of a wall interference correction system for a transonic slotted wall wind tunnel. At first, different sets of uncorrected aerodynamic coefficients were generated by physically changing the boundary condition of the test section walls. Then, wall interference corrections were computed and applied to all data points. Finally, an interpolation of the corrected aerodynamic coefficients was performed. This interpolation made sure that the corrected Mach number of a given run would be constant. Overall, the agreement between corresponding interpolated lift, drag, and pitching moment coefficient sets was very good. Buoyancy corrections were also investigated. These studies showed that the accuracy goal of one drag count may only be achieved if reliable estimates of the wall interference induced buoyancy correction are available during a test.Ulbrich, Norbert and Boone, Alan R.Ames Research CenterCORRECTION; TRANSONIC WIND TUNNELS; WALL FLOW; WIND TUNNEL TESTS; AERODYNAMIC INTERFERENCE; SLOTTED WIND TUNNELS; INTERPOLATION; MACH NUMBER; PITCHING MOMENTS; LIFT; BOUNDARY CONDITIONS; ACCURACY; BUOYANCY