Adaptive Wall Wind Tunnel Investigation of a Circulation Controlled Circular Cylinder PDF Download

Author: Roland Gunther Berndt
Publisher:
ISBN:
Category :
Languages : en
Pages : 266

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Author: Fabrizio Adalberto Maria Dionisio
Publisher:
ISBN:
Category : Wind tunnels
Languages : en
Pages : 320

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Author: Michael Joseph Bishop
Publisher:
ISBN:
Category :
Languages : en
Pages : 140

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A renovation of an adaptive-wall wind tunnel was completed to improve flow quality, automate data acquisition, integrate a three-axis traversing mechanism, and regain functionality of an adaptive-wall test section. Redesign of the settling chamber significantly improved flow quality, with the resulting turbulence intensity of 0.3% and flow uniformity of ±0.6% matching characteristics of research-grade wind tunnels. The functionality of the adaptive-wall test section was tested by analyzing the effect of wall adaptation on flow development over a circular cylinder. Experiments were carried out for a Reynolds number (Red) of 57,000 for three blockage ratios: 5%, 8%, and 17%. Measurements were made in three wall configurations: geometrically straight walls (GSW), aerodynamically straight walls (ASW), and streamlined walls (SLW). Solid blockage effects were clearly evident in cylinder surface pressure distributions for the GSW and ASW configurations, manifested by an increased peak suction and base suction. Upon streamlining the walls, pressure distributions for each blockage ratio matched distributions expected for low blockage ratios. Wake blockage limited wake growth in the GSW configuration at 7.75 and 15 diameters downstream of the cylinder for blockages of 17% and 8%, respectively. This adverse effect was rectified by streamlining the walls with the resulting wake width development matching that expected for low blockage ratios. Wake vortex shedding frequency and shear layer instability frequency increased in the GSW and ASW configurations with increasing blockage ratio. Invariance of the near wake width with wall configuration suggests that frequency increase is caused by the increased velocity due to solid blockage effects. For all the blockage ratios investigated, the increased wake vortex shedding frequency observed in the ASW and GSW configurations was corrected in the SLW configuration, with the resulting Strouhal numbers of about 0.19, matching that expected for low blockage ratios at the investigated Red.

Author:
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ISBN:
Category :
Languages : en
Pages : 110

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A two-dimensional circulation control (4.25-in. diam. x 24-in. span) model was designed for installation in the Naval Postgraduate School oscillating flow, low speed wind tunnel. An adjustable, tangential blowing slots was included in the design to provide circulation control capability using the Coanda flow effect aft of the spanwise slot. Orifice locations were defined for obtaining surface static pressures which could be subsequently processed to yield sectional lift and drag coefficients. Pressure system calibrations were also made to determine the dynamic transfer function from a simulation of the model's static pressure orifice when connected to the pressure transducer. Similar transfer functions were determined for a static pressure probe. The existing data acquisition system was used to process the sampled digital data sequence. Clear-tunnel flow calibrations were performed in the (2'x2'x18.6' long) test section at a mid-length test station using a hot-wire and the calibrated static pressure probe. An oscillating velocity was superimposed upon a mean free stream motion using an existing rotating mechanism of 4 synchronized shutters at the end of the test section. Analytic estimates of both static pressure and velocity perturbations correlated well with experimental results for a frequency range of 14-40 Hz with a fixed value of shutter blockage.

Author: Robert J. Vidal
Publisher:
ISBN:
Category : Aerodynamics, Transonic
Languages : en
Pages : 70

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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.

Author: Groves Eckley Herrick
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Marie H. Tuttle
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ISBN:
Category : Wind tunnel walls
Languages : en
Pages : 44

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Author: Joel L. Everhart
Publisher:
ISBN:
Category : Aerodynamics, Transonic
Languages : en
Pages : 52

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Author: Chester D. Mayerson
Publisher:
ISBN:
Category :
Languages : en
Pages : 91

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Author: Edward T. Schairer
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 40

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