Christian Schnepf

Numerical investigation on the development of the Phantom Yaw Effect on a maneuvering missile

The aerodynamics of a pitching slender body at

CFD Study on a Pitching Missile with Respect to Reduce the Phantom Yaw Effect

M=0.8

Optical Wall Shear Stress Measurements on the Leeward Side of a Delta Wing

with two different pivot locations have been numerically investigated using URANS with a two equation turbulence model. Identical to an experiment a sinusoidal motion between

Experimental und numerical investigation of the aerodynamic characteristic of a generic transonic missile

\alpha=0^\circ

WAVE DRAG REDUCTION DUE TO A SELF-ALIGNING AERODISK

and

Numerical investigation on the Phantom Yaw Effect due to small nose deflections

44^\circ

Wave drag reduction with a self-aligning aerodisk on a missile configuration

was defined. Due to a deflection of the symmetric numerical grid a vortex asymmetry the so called Phantom Yaw Effect was triggered. While the lift and drag are highly dependent on the pivot the side force and the yawing moment are less sensitive to the pivot. With the help of a forced symmetric separation at the nose the Phantom Yaw Effect could be reduced and the load change at higher angles of attack could be eliminated. A comparison with experimental shows a less good agreement.

Numerical study on the impact of a maneuver on the Phantom-Yaw-Effect in transonic flow

This numerical study is about the alleviation of the Phantom Yaw Effect on a pitching missile. A pair of slit shaped side jets, so called aerostrakes is used to force a symmetric separation at the shoulder of the missile. The unsteady Reynolds averaged Navier-Stokes equations are solved with a two equation turbulence model for a case with and without aerostrakes. The missile is pitching sinusoidally at a frequency of 5 Hz between \(0^\circ \le \alpha \le 44^\circ \) at Mach 0.8. The results show that the magnitude of the side force, resulting from Phantom Yaw, is reduced by the aerostrakes and the onset angle for the PYE is shifted to higher angle of attack. A reversal of sign of both the side force and yawing moment is also prevented when using the aerostrakes. Furthermore, the influence of the pitching motion on the relevant aerodynamic coefficients is less profound in the case with aerostrakes.

Experimentelle und numerische Analyse der aerodynamischen Charakteristik eines transsonischen Flugkörpers

Bereits durchgefuhrte Untersuchungen auf der Leeseite eines angestellten Deltaflugels (im Anstellwinkelbereich von 5° bis 25°) haben demonstriert, dass die Dicke der Olschicht aus einer Sequenz von Olfilminterferenzbildern ausreichend genau bestimmt werden kann, um quantitative Wandschubspannungsverteilungen zu erhalten. Die aktuelle Arbeit erweitert die durchgefuhrten Wandschubspannungsmessungen um die zusatzlichen Flugelanstellwinkel von 30°, 32° und 35°. Auserdem wurden parallel neue numerische RANS-Simulationen fur die gemessenen Konfigurationen mit Hilfe des TAU-Codes durchgefuhrt, um die mogliche Auswirkung des Grenzschichtzustandes auf die Stromungstopologie zu untersuchen.

Optische Wandschubspannungsmessung auf der Leeseite eines Deltaflügels

A study of the aerodynamic characteristics of two missile configurations has been performed using the data of an experiment, of a semi-empirical aerodynamic prediction code (Missile Datcom) and a RANS flow solver (TAU). The aerodynamic coefficients for different angles of attack and roll angles for Mach numbers of M= 0.85 and 1.2 are compared. Considering the design of the configurations one is rather unconventional with large aspect ratio wings. Whereas the other one has conventional wings with a small aspect ratio. The latter sustains large lift forces at high angles of attack due to the occurrence of vortices while the former performs better at low angles of attack. The comparison of the experimental data with the TAU predicted aerodynamic coefficients shows a good agreement for both configurations in the entire AoA-range. Regarding Missile Datcom, for the unconventional design the accuracy of the predicted data decreases with increasing angle of attack but remains almost constant for the conventional.