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A test campaign was conducted in the open-jet test section of the NASA Langley Research Center's 14- by 22-Foot Subsonic Tunnel on a 10%-scale semispan version of the High-Lift Common Research Model incorporating a leading-edge slat, a trailing-edge flap, and removable high-fidelity main landing gear. Computational simulations were used to support the model development, provide important information such as load distributions along the high-lift elements, and aid in the design of noise reduction devices. Aerodynamic and far-field acoustic measurements were obtained on baseline and acoustically treated model configurations using an ensemble of time-averaged and unsteady surface pressure sensors paired with a traversing 97-microphone phased array viewing the pressure side of the airframe. A deconvolution method incorporating corrections for shear layer acoustic wave decorrelation was employed to determine the locations and strengths of relevant noise sources along the span of the slat and in the vicinity of the flap edges and landing gear. The main goal of the test campaign was to use the surface pressure and array data to evaluate the effectiveness of various slat noise reduction concepts. It was found that slat-gap fillers produced significant broadband noise reduction with minimal aerodynamic performance penalties for all Mach numbers and airfoil angles of attack that were investigated. The test campaign clearly demonstrated the noise reduction benefits that can be obtained by applying appropriate treatments to leading-edge slats on commercial transport-class aircraft. [ABSTRACT FROM AUTHOR]

Details a study which presented a computational aeroacoustic analysis of slat trailing-edge flow. Feature of the experimental data; Acoustic procedure; Results and conclusions.

Examines how the computational aeroacoustic methodology and parallel computers are used in the simulation of the development of a tip vortex. Why a three-dimensional Euler code, implemented using the message passing library and Fortran 90 on the IBM SP2, is used; Comparisons with experimental data showing that the tip vortex is predicted.

Provides information on a study which used a computational aeroacoustics methodology and parallel computers to examine the broadband blade noise. Description of the interaction of a vortical gust with a finite thickness airfoil; Use of a two-dimensional Navier-Stokes code; Demonstration of the steady and unsteady algorithms.

The slat of a high-lift wing can be a significant noise source during approach and landing. This paper describes an experimental study of the effects of two passive devices (namely, slat extensions and a cove filler) on the aerodynamics and acoustic radiation from a 30P30N model. Test conditions include three effective free-air angles of attack of 5.5, 7.5, and 13 deg, as well as three Reynolds numbers of 1.2, 1.5, and 1.71×106. Steady surface pressure measurements are used to assess the aerodynamics near the midspan section. Unsteady surface pressure and far-field acoustic array measurements are performed to evaluate the near- and far-field pressure fluctuations, respectively. Delay-and-sum beamforming is applied to localize the noise sources and to provide integrated spectra. The slat cusp extensions barely affect the mean Cp distribution, whereas the longest extension achieves up to a 5.4 dB reduction in the overall sound pressure level. The slat-cove filler yields an even higher noise reduction that is lower than the baseline by up to 14 dB. Even though the aerodynamic assessment of the cove filler is incomplete due to the covered pressure ports, the mean Cp distribution over the remaining surface of the model indicates a rather small change compared with the baseline measurements. [ABSTRACT FROM AUTHOR]

The work presented in this paper is a culmination of a multiyear joint experimental and computational effort to explore the feasibility of using active flow control (AFC) on a simple hinged flap system for recovering lift comparable to a conventional high-lift system consisting of Fowler flaps. The baseline configuration chosen for this work is the high-lift version of the NASA Common Research Model (CRM), which is a representative modern aircraft consisting of wing, fuselage, nacelle/pylon, slats, Fowler flaps, and slat and flap brackets. A simplified high-lift (SHL) system was created by replacing the Fowler flaps and flap brackets with a simple hinged flap system equipped with integrated modular AFC cartridges on the suction surface of the flap shoulder, and the resulting geometry is known as the CRM-SHL-AFC configuration. Parametric studies were conducted in the earlier phases of this effort to numerically evaluate and downselect the more efficient AFC designs for wind-tunnel tests. These simulations were performed with the PowerFLOW® code, which is a lattice-Boltzmann-based computational fluid dynamics code. Good agreement was reported in a previous paper between the numerical results and the experimental data for the lift characteristics of the CRM-SHL-AFC configuration as a function of actuation levels at the nominal landing conditions. The current effort is focused on demonstrating the applicability of the PowerFLOW code for predicting the aerodynamic performance of the conventional and the AFC-enabled simplified high-lift CRM configurations for a broad angle of attack range, including maximum lift conditions. [ABSTRACT FROM AUTHOR]

The current effort characterizes the details of flow interactions and wake interference effects between two cylinders in a tandem configuration. This setup is representative of several component-level flow interactions that occur when air flows over the main landing gear of aircraft. Such interactions are likely to have a significant impact on the noise radiation associated with the undercarriage. This paper focuses on two-dimensional, time-accurate flow simulations of two distinct tandem cylinder flowregimes, associated with short and intermediate separation distances between the two cylinders. Unsteady Reynolds averaged Navier-Stokes simulations using a two-equation turbulence model run at a Reynolds number of 1.66 x 1055 and a Mach number of 0.166 are presented. Emphasis is placed on understanding both the time-averaged and unsteady flow features between the two cylinders and in the wake of the rear cylinder. Predicted mean-flow quantities and vortex shedding frequencies show reasonable agreement with measured data for both cylinder spacings. Computations for the short separation distance exhibit a nonphysical decay of flow unsteadiness with time; however, the predicted sensitivity of the mean lift coefficient to small variations in the upstream flow angularity explains the asymmetric flowfield observed in the present and previous measurements. [ABSTRACT FROM AUTHOR]