Computational model for electromagnetic interaction of conformal antennas and aircraft structure

The aim of this paper is to describe a computational model for assessment of electromagnetic interaction of conformal antennas with the aircraft structure. The conformal array antennas are assumed to be flush-mounted on the surface of an aircraft. The model assumes a receiving conformal antenna, which is illuminated by a plane wave. The...

Electro-magnetic analysis of geometrically perturbed objects

The design of antennas on spacecraft and aircraft as well as the prediction of Radar Cross Sections of fighter aircraft require the geometrical modelling and electro-magnetic analysis of antennas and scattering objects. The electro-magnetic analysis can be performed by means of classical computational methods, which are based on the Stratton-Chu...

TULIPS: A method to calculate transonic potentional flow about oscillating airfoils

A description is given of TULIPS - a method for Transonic Unsteady Lifting Inviscid Potential-flow Simulation. The Mathematical formulation and the numerical approach are presented for flow about oscillating airfoils. TULIPS is based on the numerical integration of the unsteady full-potential equation in generalized coordinates. The equation is...

Multigrid methods in boundary element calculations

In this paper multigrid iterative methods are advocated for the fast solution of algebraic systems occurring in boundary element calculations. Multigrid methods combine relaxation schemes for reducing high-frequency errors and coarse grid corrections for diminishing low-frequency errors. The choice of the relaxation scheme is found to be...

On the evaluation of aerodynamic influence coefficients

In this paper numerical schemes are discussed to reduce the computational work involved with the evaluation of the aerodynamic influence coefficients of panel methods. The applicability of these schemes is investigated to the calculation of potential flow around an airfoil. The interest concerns the decomposition of the boundary integral...

Calculation of 2-D unsteady transonic full potential flow about oscillating airfoils by two complementary appraches

Results of 2-D unsteady transonic flow calculations for AGARD standard aeroelastic configurations are presented, which have been obtained from NLR's numerical methods for the solution of the unsteady full potential equation. Two complementary methods have been applied to oscillating transonic flow about thick blunt-nosed airfoils: 1) the time...

Numerical treatment of shocks in unsteady potential flow computation

The numerical treatment of moving shocks in unsteady transonic potential flow is discussed. An implicit fullyconservative finite-difference algorithm is presented, which is based on time-linearization and mass-flux splitting. For the one-dimensional problem of a travelling shock-wave, this algorithm is compared with the methods of Goorjian and...

Numerical integration of the unsteady full-potential equation with applications to transonic flow about a 2D airfoil

The numerical integration of the unsteady full-potential equation in generalized coordinates in strong conservation form is described for the computation of unsteady transonic flows. A typical feature of the present algorithm is that non-linear truncation errors are minimized by time-linearizing the full-potential equation upto second order...

Implicit finite-difference method for the calculation of unsteady transonic potential flow about 2D airfoils: A discussion

A thorough discussion of the mathematical modelling of unsteady transonic flow is presented. Starting from the Euler equations potential theory is derived and applied to the flow about a 2D airfoil. Motions considered include rigid body motions as well as deformations of the airfoil itself. The full-potential equation is formulated on...

Transonic wind-tunnel tests on an oscillating wing with external store. Part IV: The Wing with underwing-store

A wind-tunnel investigation was carried out on an oscillating model of the F-5 wing with and without an external store (AIM-9J missile). Detailed steady and unsteady pressure distributions were obtained over the wing, while on the store total aerodynamic loads were measured. The tests covered the Mach number range between Ma = 0.6 and Ma = 1.35,...

Transonic wind-tunnel tests on an oscillating wing with external store. Part III: The wing with tipstore

A wind-tunnel investigation was carried out on an oscillating model of the F-5 wing with and without an external store (AIM-9J missile). Detailed steady and unsteady pressure distributions were obtained over the wing, while on the store total aerodynamic loads were measured. The tests covered the Mach number range between Ma = 0.6 and Ma = 1.35,...

Transonic wind-tunnel tests on an oscillating wing with external store. Part II: The clean wing

A wind-tunnel investigation was carried out on an oscillating ng model of the F-5 wing with and without an external store (AIM-9J missile) . Detailed steady and unsteady pressure distributions were obtained over the wing, while on the store total aerodynamic loads were obtained. In addition, wind-tunnel wall pressures were measured. The tests...

Unsteady airloads on an oscillating supercritical airfoil

Results are presented of unsteady pressure measurements on a two-dimensional model of the supercritical NLR 7301 airfoil performing pitching oscillations about an axis at ItO per cent of the chord. Paper presented at the Specialists' Meeting on Unsteady Airloads in Separated and Transonic Flow in conjunction with the 44th meeting of the...

Results of pressure measurements on an airfoil with oscillating flap in two-dimensional high subsonic and transonic flow (zero incidence and zero mean flap position)