scholarly journals University of Nebraska unmanned aerial system (UAS) profiling during the LAPSE-RATE field campaign

2021 ◽  
Vol 13 (6) ◽  
pp. 2457-2470
Author(s):  
Ashraful Islam ◽  
Ajay Shankar ◽  
Adam Houston ◽  
Carrick Detweiler
Keyword(s):  
Three Dimensional ◽  
Boundary Layer Transition ◽  
Lapse Rate ◽  
Unmanned Aerial Systems ◽  
Layer Transition ◽  
Full Dataset ◽  
Temperature And Humidity ◽  
Remotely Piloted Aircraft ◽  
University Of Nebraska Lincoln ◽  
Convection Initiation

Abstract. This paper describes the data collected by the University of Nebraska-Lincoln (UNL) as part of the field deployments during the Lower Atmospheric Process Studies at Elevation – a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE) flight campaign in July 2018. The UNL deployed two multirotor unmanned aerial systems (UASs) at multiple sites in the San Luis Valley (Colorado, USA) for data collection to support three science missions: convection initiation, boundary layer transition, and cold air drainage flow. We conducted 172 flights resulting in over 21 h of cumulative flight time. Our novel design for the sensor housing onboard the UAS was employed in these flights to meet the aspiration and shielding requirements of the temperature and humidity sensors and to separate them from the mixed turbulent airflow from the propellers. Data presented in this paper include timestamped temperature and humidity data collected from the sensors, along with the three-dimensional position and velocity of the UAS. Data are quality-controlled and time-synchronized using a zero-order-hold interpolation without additional post-processing. The full dataset is also made available for download at https://doi.org/10.5281/zenodo.4306086 (Islam et al., 2020).

scholarly journals University of Nebraska UAS profiling during LAPSE-RATE

2020 ◽  
Author(s):  
Ashraful Islam ◽  
Ajay Shankar ◽  
Adam Houston ◽  
Carrick Detweiler
Keyword(s):  
Three Dimensional ◽  
Boundary Layer Transition ◽  
Lapse Rate ◽  
Unmanned Aerial Systems ◽  
Layer Transition ◽  
Full Dataset ◽  
Remotely Piloted Aircraft ◽  
Field Deployment ◽  
University Of Nebraska Lincoln ◽  
Convection Initiation

Abstract. This paper describes the data collected by the University of Nebraska-Lincoln (UNL) as part of the field deployment during the Lower Atmospheric Process Studies at Elevation – a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE) flight campaign in July 2018. UNL deployed two multirotor unmanned aerial systems (UASs) at various sites in the San Luis Valley (Colorado, USA) for data collection in support of three science missions: convection-initiation, boundary layer transition, and cold air drainage flow. We conducted 172 flights resulting in over 1300 minutes of cumulative flight time. Our novel design for the sensor housing onboard the UAS was employed in these flights to meet the aspiration and shielding requirements of the temperature/humidity sensors, and attempt to separate them from the mixed turbulent airflow from the propellers. Data presented in this paper include time-stamped temperature and humidity data collected from the sensors, along with the three-dimensional position and velocity of the UAS. Data are quality controlled and time-synchronized using a zero-order-hold interpolation without additional post processing. The full dataset is also made available for download at (https://doi.org/10. 5281/zenodo.4306086 (Islam et al. , 2020)).

scholarly journals University of Kentucky measurements of wind, temperature, pressure and humidity in support of LAPSE-RATE using multi-site fixed-wing and rotorcraft UAS

2020 ◽  
Author(s):  
Sean C. C. Bailey ◽  
Michael P. Sama ◽  
Caleb A. Canter ◽  
L. Felipe Pampolini ◽  
Zachary S. Lippay ◽  
...  
Keyword(s):  
Ground Level ◽  
Boundary Layer Transition ◽  
Lower Atmosphere ◽  
Lapse Rate ◽  
Data Repository ◽  
Unmanned Aerial Systems ◽  
University Of Kentucky ◽  
Layer Transition ◽  
Remotely Piloted Aircraft ◽  
Convection Initiation

Abstract. In July 2018, unmanned aerial systems (UAS) were deployed to measure the properties of lower atmosphere within the San Luis Valley, an elevated valley in Colorado, USA as part of the Lower Atmospheric Profiling Studies at Elevation – a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE). Measurement objectives included detailing boundary-layer transition, canyon cold-air drainage, and convection initiation within the valley. Details of the contribution to LAPSE-RATE made by University of Kentucky are provided here, which include measurements by seven different fixed-wing and rotorcraft UAS totaling over 178 flights with validated data. The data from these coordinated UAS flights consist of thermodynamic and kinematic variables (air temperature, humidity, pressure, wind speed and direction) and include vertical profiles up to 900 m above the ground level and horizontal transects up to 1500 m in length. These measurements have been quality controlled and are openly available in the Zenodo LAPSE-RATE community data repository (https://zenodo.org/communities/lapse-rate/), with the University of Kentucky data available at https://doi.org/10.5281/zenodo.3701845 (Bailey et al., 2020).

scholarly journals University of Kentucky measurements of wind, temperature, pressure and humidity in support of LAPSE-RATE using multisite fixed-wing and rotorcraft unmanned aerial systems

2020 ◽  
Vol 12 (3) ◽  
pp. 1759-1773 ◽  
Author(s):  
Sean C. C. Bailey ◽  
Michael P. Sama ◽  
Caleb A. Canter ◽  
L. Felipe Pampolini ◽  
Zachary S. Lippay ◽  
...  
Keyword(s):  
Ground Level ◽  
Boundary Layer Transition ◽  
Lower Atmosphere ◽  
Lapse Rate ◽  
Data Repository ◽  
Unmanned Aerial Systems ◽  
University Of Kentucky ◽  
Layer Transition ◽  
The University ◽  
Aerial Systems

Abstract. In July 2018, unmanned aerial systems (UASs) were deployed to measure the properties of the lower atmosphere within the San Luis Valley, an elevated valley in Colorado, USA, as part of the Lower Atmospheric Profiling Studies at Elevation – a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE). Measurement objectives included detailing boundary layer transition, canyon cold-air drainage and convection initiation within the valley. Details of the contribution to LAPSE-RATE made by the University of Kentucky are provided here, which include measurements by seven different fixed-wing and rotorcraft UASs totaling over 178 flights with validated data. The data from these coordinated UAS flights consist of thermodynamic and kinematic variables (air temperature, humidity, pressure, wind speed and direction) and include vertical profiles up to 900 m above the ground level and horizontal transects up to 1500 m in length. These measurements have been quality controlled and are openly available in the Zenodo LAPSE-RATE community data repository (https://zenodo.org/communities/lapse-rate/, last access: 23 July 2020), with the University of Kentucky data available at https://doi.org/10.5281/zenodo.3701845 (Bailey et al., 2020).

Osborne Reynolds: Energy Methods in Transition and Loss Production: A Centennial Perspective

1995 ◽  
Vol 117 (1) ◽  
pp. 142-153 ◽  
Author(s):  
J. Moore ◽  
J. G. Moore
Keyword(s):  
Kinetic Energy ◽  
Turbulent Flows ◽  
Three Dimensional ◽  
Boundary Layer Transition ◽  
Turbulence Energy ◽  
Energy Methods ◽  
Layer Transition ◽  
Energy Balance Method ◽  
European Working ◽  
Transition Modeling

Osborne Reynolds’ developments of the concepts of Reynolds averaging, turbulence stresses, and equations for mean kinetic energy and turbulence energy are viewed in the light of 100 years of subsequent flow research. Attempts to use the Reynolds energy-balance method to calculate the lower critical Reynolds number for pipe and channel flows are reviewed. The modern use of turbulence-energy methods for boundary layer transition modeling is discussed, and a current European Working Group effort to evaluate and develop such methods is described. The possibility of applying these methods to calculate transition in pipe, channel, and sink flows is demonstrated using a one-equation, q-L, turbulence model. Recent work using the equation for the kinetic energy of mean motion to gain understanding of loss production mechanisms in three-dimensional turbulent flows is also discussed.

Numerical simulation of boundary-layer transition and transition control

1989 ◽  
Vol 199 ◽  
pp. 403-440 ◽  
Author(s):  
E. Laurien ◽  
L. Kleiser
Keyword(s):  
Boundary Layer ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Transition Process ◽  
Numerical Results ◽  
Boundary Layer Transition ◽  
Two Dimensional ◽  
Layer Transition ◽  
Longitudinal Vortices ◽  
Tollmien Schlichting

The laminar-turbulent transition process in a parallel boundary-layer with Blasius profile is simulated by numerical integration of the three-dimensional incompressible Navier-Stokes equations using a spectral method. The model of spatially periodic disturbances developing in time is used. Both the classical Klebanoff-type and the subharmonic type of transition are simulated. Maps of the three-dimensional velocity and vorticity fields and visualizations by integrated fluid markers are obtained. The numerical results are compared with experimental measurements and flow visualizations by other authors. Good qualitative and quantitative agreement is found at corresponding stages of development up to the one-spike stage. After the appearance of two-dimensional Tollmien-Schlichting waves of sufficiently large amplitude an increasing three-dimensionality is observed. In particular, a peak-valley structure of the velocity fluctuations, mean longitudinal vortices and sharp spike-like instantaneous velocity signals are formed. The flow field is dominated by a three-dimensional horseshoe vortex system connected with free high-shear layers. Visualizations by time-lines show the formation of A-structures. Our numerical results connect various observations obtained with different experimental techniques. The initial three-dimensional steps of the transition process are consistent with the linear theory of secondary instability. In the later stages nonlinear interactions of the disturbance modes and the production of higher harmonics are essential.We also study the control of transition by local two-dimensional suction and blowing at the wall. It is shown that transition can be delayed or accelerated by superposing disturbances which are out of phase or in phase with oncoming Tollmien-Schlichting instability waves, respectively. Control is only effective if applied at an early, two-dimensional stage of transition. Mean longitudinal vortices remain even after successful control of the fluctuations.

On the catalytic role of the phase-locked interaction of Tollmien–Schlichting waves in boundary-layer transition

2007 ◽  
Vol 590 ◽  
pp. 265-294 ◽  
Author(s):  
XUESONG WU ◽  
P. A. STEWART ◽  
S. J. COWLEY
Keyword(s):  
Exponential Growth ◽  
Perfect Match ◽  
Three Dimensional ◽  
Phase Speed ◽  
Boundary Layer Transition ◽  
Critical Layer ◽  
Back Reaction ◽  
S Wave ◽  
Layer Transition ◽  
Tollmien Schlichting

This paper is concerned with the nonlinear interaction between a planar and a pair of oblique Tollmien–Schlichting (T-S) waves which are phase-locked in that they travel with (nearly) the same phase speed. The evolution of such a disturbance is described using a high-Reynolds-number asymptotic approach in the so-called ‘upper--branch’ scaling regime. It follows that there exists a well-defined common critical layer (i.e. a thin region surrounding the level at which the basic flow velocity equals the phase speed of the waves to leading order) and the dominant interactions take place there. The disturbance is shown to evolve through several distinctive stages. In the first of these, the critical layer is in equilibrium and viscosity dominated. If a small mismatching exists in the phase speeds, the interaction between the planar and oblique waves leads directly to super-exponential growth/decay of the oblique modes. However, if the modes are perfectly phase-locked, the interaction in the first instance affects only the phase of the amplitude function of the oblique modes (so causing rapid wavelength shortening), while the modulus of the amplitude still evolves exponentially until the wavelength shortening produces a back reaction on the modulus (which then induces a super-exponential growth). Whether or not there is a small mismatch or a perfect match in the phase speeds, once the growth rate of the oblique modes becomes sufficiently large, the disturbance enters a second stage, in which the critical layer becomes both non-equilibrium and viscous in nature. The oblique modes continue to experience super-exponential growth, albeit of a different form from that in the previous stages, until the self-interaction between them, as well as their back effect on the planar mode, becomes important. At that point, the disturbance enters a third, fully interactive stage, during which the development of the disturbance is governed by the amplitude equations with the same nonlinear terms as previously derived for the phase-locked interaction of Rayleigh instability waves. The solution develops a singularity, leading to the final stage where the flow is governed by fully nonlinear three-dimensional inviscid triple-deck equations. The present work indicates that seeding a planar T-S wave can enhance the amplification of all oblique modes which share approximately its phase speed.

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