Physics and Control of Transonic Buffet

The flight envelope of an aircraft operating at high subsonic velocities is bounded by several limitations, one of these consists in thewing experiencing oscillations of a shockwave on its suction side for a certain range ofMach number (Ma), angle of attack (®) and Reynolds number (Re). This phenomenon is referred to as transonic buffet and it...

Experimental Characterization of Upper Trailing Edge Flaps for Transonic Buffet Control

This experimental study investigates the possibility of controlling transonic buffet by means of a trailing edge flap with an upward deflection (referred to as “upper trailing edge flap”, or: UTEF). Different geometries (straight and serrated) and dimensions of UTEFs (with heights ranging between 1 and 2% of the chord) have been studied with...

A Response Spectrum Analysis of Wind Deflection in Railway Overhead Contact Lines Using Pseudo-Excitation Method

The wind deflection of overhead contact lines (OCLs) challenges the stable and safe operation of electrified railways. The steady wind causes the static deflection of the contact line, while the fluctuating wind leads to the OCL buffeting. This paper performs a response spectrum analysis of the wind deflection caused by the combined effects...

Experimental investigation of transonic buffet on swept wings: A comparative study between 2D and 3D flow and analysis of sweep angle influence using stereoscopic PIV and Background Oriented Schlieren

Transonic buffet is an aerodynamic instability that appears on aerofoils and wings at certain combinations of Mach number and angle of attack, and which limits the aircraft flight envelope. This thesis project presents an experimental<br/>investigation of buffet employing stereoscopic PIV and Background Oriented Schlieren. By using four...

Stall Buffet Modeling using Swept Wing Flight Test Data

As of April 2019, upset prevention and recovery training in flight simulation training devices is a mandatory practice for commercial and civil aircraft pilots. Aircraft stalls are a well-known upset type, therefore simulation of aircraft stall behavior is required. A key characteristic of stalls is the buffeting component, which in current...

Sky-dive Cavity Buffeting Noise Reduction

Cavity buffeting noise is the main contributor to discomfort in sky-dive tunnels. Low frequency noise, generated by self-sustained cavity shear-layer oscillations, similar to automotive sunroof-buffeting noise and side-window buffeting noise, is observed in sky-dive tunnels. Typical low frequencies are not conventionally audible to the human ear...

The Effect of Nozzle Length and Exhaust Plume on Transonic and Supersonic Axisymmetric Base Flows: An Experimental Study

A combined PIV and Schlieren measurements have been carried out in the transonic-supersonic wind tunnel (TST-27) to investigate the effect of exhaust plume and the variation in nozzle length on the flow topology and mean pressure distribution on the wake of axisymmetric backward facing step model at freestream Mach numbers of 0.76 and 2.20,...

On the unsteady development of the flow under transonic Buffet conditions: Experimental study of the interaction of shock and pressure waves using PIV and Schlieren visualization

This thesis presents an experimental study of the unsteady phenomenon known as transonic buffet. Completely developed in the High Speed Lab of the Aerospace Faculty at TU Delft (The Netherlands), the experiments were conducted in the transonic/supersonic wind tunnel TST-27. In order to achieve time and spatial resolution of the phenomenon, high...

Buffet envelope prediction of transport aircraft during the conceptual design phase

During conceptual design a problem arises when predicting the buffet onset boundary. Due to the pressure on payload-range and cruise altitude capability, improvement on the buffet onset boundary is often of great importance. It is one of the primary constraints in establishing the low and transonic speed performance capabilities of transport...

Fluid Structure Interaction at the Ariane-5 Nozzle Section by Advanced Turbulence Models

Substantial requirements for future rocket technologies are the cost-efficient access to orbit as well as the increase in the system reliability. Concerning these requirements the engine is one of the most important parts and a deeper insight into the unsteady phenomena during the start phase of modern launchers is essential. Especially unsteady...

Physical and numerical aspects of aeroelastic simulations

Comparison of Fokker F28 wind tunnel and flight data; a summary

For an accurate prediction of aircraft characteristics the wind tunnel tests are of paramount impoitance. Therefore the significance of the test results and available extrapolation techniques have to be investigated as thoroughly as possible. For this reason a program for comparing wind tunnel and flight test data of the Fokker F-28 was set up,...