A time domain approach for predicting the coupled flutter and buffeting response of long span bridges is presented. The frequency dependent unsteady aerodynamic forces are represented by the convolution integrals involving the aerodynamic impulse function and structural motions or wind fluctuations. The aerodynamic impulse functions are derived from experimentally measured flutter derivatives, ...

The spectroscopic diagnostic technique of two photon absorption laser-induced fluorescence (LIF) of atomic species for non-intrusive arc jet flow property measurement was first implemented at NASA Ames in the mid-1990s. In 2013-2014, NASA combined the agency’s large-scale arc jet test capabilities at NASA Ames. Concurrent with that effort, the agency also sponsored a project to establish two co...

This paper first discusses the current status of natural hazard-induced disasters, with special focus on devastating wind-related disasters in the Asian region. The importance of the combined effects of wind and water hazards, the importance of performance of cladding and components in wind-resistant design of buildings, and deterioration of metal roofing systems of long-span structures mainly ...

3D techniques are increasingly used in aerospace industry to improve quality and performance of aircrafts. This paper presents a 3D imaging technique for studying the aerodynamic shape and flight performance of micro air vehicles. 3D stereoscopic vision, based upon stroboscopic imaging, was utilized to obtain the 3D information of the aircraft’s flexible aerodynamic surface. The aircraft models...

Insect wings are deformable structures that change shape passively and dynamically owing to inertial and aerodynamic forces during flight. It is still unclear how the three-dimensional and passive change of wing kinematics owing to inherent wing flexibility contributes to unsteady aerodynamics and energetics in insect flapping flight. Here, we perform a systematic fluid-structure interaction ba...

The paper presents the modeling of nonlinear longitudinal aerodynamics using flight data of Hansa-3 aircraft at high angles of attack near stall. The Kirchhoff’s quasi-steady stall model has been used to incorporate nonlinear aerodynamic effects in the aerodynamic model used to estimate the parameters, thereby, making the aerodynamic model nonlinear. The Maximum Likelihood method has been appli...

This article presents the temperature and emissivity estimation of metals around their melting points using different techniques, which are based on deterministic (ordinary least squares) Bayesian approaches. Linear non-linear models examined. The experimental data consist radiative fluxes at six wavelengths, collected by a pyrometer. apparatus is dedicated to characterization physical properti...

Acoustic waves existing in hypersonic boundary layers act as a heat pump that transfers energy from the sonic line to wall causing temperature rise, which explains newly identified aerodynamic heating related Mack's second mode perspective of thermoacoustic effects. The analysis data direct numerical simulations shows mode, belonging family trapped acoustic waves, is highly amplified Mach 6 lay...

Turning is crucial for animals, particularly during predator-prey interactions and to avoid obstacles. For flying animals, turning consists of changes in (i) flight trajectory, or path of travel, and (ii) body orientation, or 3D angular position. Changes in flight trajectory can only be achieved by modulating aerodynamic forces relative to gravity. How birds coordinate aerodynamic force product...

Conventional quaternion based methods have been extensively employed for spacecraft attitude control where the aerodynamic forces can be neglected. In the presence of aerodynamic forces, the flight attitude control is more complicated due to aerodynamic moments and inertia uncertainties. In this paper, a robust nero-adaptive quat...