Introduction to Wind Engineering – Lecture Review 1

Vocabulary flashcards covering key terms, periods, aerodynamic concepts, flight effects, hazards, practical tools, and advanced aerospace applications drawn from the lecture on wind engineering.

Wind Engineering

The rational study of interactions between wind in the atmospheric boundary layer and people, structures, and activities at Earth’s surface (Cermak, 1975).

Atmospheric Boundary Layer

The lowest portion of the atmosphere directly influenced by its contact with Earth’s surface, where wind–structure interactions are most significant.

Traditional Period (≈ pre-1750)

Era when structures were designed against wind primarily by trial, error, and local building traditions.

Empirical Period (1750–1900)

Phase marked by observation-based rules as bridges, railways, and larger infrastructure drove interest in wind effects.

Establishment Period (1900–1960)

Time when aerodynamic theory, wind tunnels, and boundary-layer research provided a scientific foundation for wind engineering.

Period of Growth (1960–1980)

Post-WWII prosperity spurred rapid advances and widespread application of wind-engineering principles.

Modern Period (1980–present)

Current era characterized by extensive use of Computational Fluid Dynamics (CFD) and high-performance computing in wind studies.

Computational Fluid Dynamics (CFD)

Numerical simulation technique that solves fluid-flow equations to predict wind behaviour around objects or within spaces.

Headwind

Wind blowing opposite the direction of travel; increases relative airflow, lift, and drag while reducing ground speed.

Tailwind

Wind blowing from behind the aircraft; decreases relative airflow over wings, requiring higher ground speed for take-off or landing.

Crosswind

Wind blowing perpendicular to the flight path, causing lateral drift and yaw forces that pilots must correct.

Wind Shear

Sudden change in wind speed or direction over a short distance, potentially producing violent up- or downdrafts and airspeed shifts.

Turbulence

Random, rapidly fluctuating gusts that vary lift and attitude, producing airframe shaking and control challenges.

Lift

Aerodynamic force perpendicular to the oncoming airflow; proportional to airspeed and wing characteristics.

Drag

Aerodynamic resistance parallel to the oncoming airflow; increases with speed and affects fuel efficiency.

Lateral Stability

Aircraft’s ability to resist roll disturbances and return to level flight after gusts or crosswind inputs.

Directional Stability

Tendency of an aircraft to maintain its heading and resist unwanted yaw motions in disturbed air.

Wind Correction Angle

Intentional heading offset into the wind during cruise to maintain a straight ground track in a crosswind.

Jetstream

High-speed, narrow air current at cruising altitudes that pilots exploit for tailwinds to save time and fuel.

Gust Factor

Additional speed (typically half the reported gust value) added to approach airspeed to buffer against sudden wind drops.

Weathervaning

Tendency of an aircraft on the ground to yaw into the wind, countered by rudder during take-off roll.

LLWAS (Low-Level Wind-Shear Alert System)

Airport-based sensor network that detects and warns pilots of hazardous low-altitude wind-shear conditions.

Runway Alignment

Design or selection of runways to face prevailing winds, reducing take-off and landing distances and crosswind exposure.

Airborne Wind Energy (AWE)

Renewable-energy concept using tethered kites or UAVs to capture strong high-altitude winds for electricity generation.

Ground-Generation AWE

AWE setup where tether tension drives generators on the ground as the airborne element cycles through power strokes.

Fly-Generation AWE

AWE configuration with onboard generators that send electricity down the tether from aloft.

Wind Tunnel

Controlled facility that produces uniform airflow over scaled or full-size models to measure aerodynamic forces and flow behaviour.

Boundary-Layer Wind Tunnel

Wind-tunnel type that replicates atmospheric boundary-layer profiles for realistic building and terrain studies.

RANS (Reynolds-Averaged Navier–Stokes)

CFD approach that solves time-averaged flow equations for efficient prediction of mean wind fields.

LES (Large Eddy Simulation)

CFD technique that resolves large turbulent structures while modelling smaller eddies for detailed unsteady flow analysis.

Hybrid Modeling

Combination of RANS, LES, or other methods to balance accuracy and computational cost in wind simulations.

Aerodynamic Shape Optimization

Systematic modification of aircraft geometry using CFD and algorithms to reduce drag and improve fuel efficiency.

Adjoint Method

Gradient-based optimization approach that computes sensitivity derivatives for complex shapes, enabling efficient design changes.

Carbon-Fiber-Reinforced Polymer (CFRP)

Lightweight composite with high strength-to-weight ratio used in aircraft structures to withstand wind-induced loads.

Glass-Fiber-Reinforced Polymer (GFRP)

Composite material offering good fatigue resistance, employed in aerospace components exposed to gust loading.

Thermoplastic Composites

Recyclable, weldable composite materials that offer sustainable alternatives for future aerospace structures.

Nonlinear Model Predictive Control (NMPC)

Advanced control technique that optimizes future control actions in real time, accounting for wind disturbances and system limits.

Automatic Terminal Information Service (ATIS)

Continuous broadcast of real-time weather, including winds, enabling pilots to plan safe airport operations.

Automatic Weather Observation System (AWOS)

Automated station providing real-time wind, temperature, and visibility data to enhance flight safety and forecasting.

Atmospheric Reentry

High-speed descent of a spacecraft through a planet’s atmosphere, generating intense aerodynamic heating and requiring precise wind-related modelling.

Rocket Exhaust Dispersion

Prediction of how high-velocity rocket plumes interact with structures and environment, ensuring safe launch operations.

National Full-Scale Aerodynamics Complex (NFAC)

Large wind-tunnel facility used for full-scale aerodynamic and parachute testing, including spacecraft hardware.

Entry Systems

Set of technologies—heat shields, parachutes, etc.—designed to return spacecraft safely through atmospheric reentry.

Heat Shield

Protective structure that absorbs and dissipates aerodynamic heating during spacecraft reentry.

Parachute Canopy Testing

Wind-tunnel or flight evaluation of parachute designs to verify stability and drag performance before full-scale deployment.

Tether (in AWE)

Cable connecting airborne kite/UAV to the ground station, transmitting mechanical power or electrical energy.

Crosswind Control Techniques

Combined rudder and aileron inputs used during take-off or landing to counter drift and wing lift in side winds.