Calculation of instationary pressure distributions and generalized aerodynamic forces with the doublet-lattice method

The doublet-lattice method for the calculation of pressure distributions and generalized aerodynamic forces on harmonically oscillating lifting surfaces in subsonic flow is described briefly. For a wide range of configurations calculated results are compared with results of kernel function methods and with experimental data.

Modeling of ureteral peristalsis and its clinical implications

Over the years physiologists have proposed models that would explain the function of the ureter. However, these models being qualitative were unable to predict the observed variations in the ureteral parameters and some have even been contradicted by modem physiological observations. Recently, several articles on peristaltic transport have...

Calculation of aerodynamic loads oscillating wing/store combinations in subsonic flow

A method for the calculation of aerodynamic loads on wing-store configurations oscillating in subsonic flow is presented. In this method the linearized equation for subsonic compressible flow is transformed into two sets of integral equations for the steady and a superimposed unsteady flow field. The wing loads are represented by dipole...

The effect of a pylon-mounted nacelle on the flutter behaviour of a wing-pylon-nacelle configuration

A calculation method for unsteady subsonic flow about harmonically oscillating wing-body configurations

A description is given of a panel method for the calculation of the aerodynamic loading on harmonically oscillating wing-body configurations in subsonic flow. Neglecting their thickness, the loading on the lifting surfaces is assumed to be generated by a distribution of unsteady lifting lines The loads on the body are represented by an unsteady...

Application of panel methods for unsteady subsonic flow

This paper gives a survey of results obtained at the NLR with two panel methods for the calculation of the aerodynamic loading on oscillating airplane configurations in subsonic flow. The methods involved are: the doublet-lattice method for thin lifting surfaces and the NLRI-panel method for wing-body combinations. After a short outline of both,...

The use of panel methods with a view to problems in aircraft dynamics

A survey is given of the basic principles of the panel methods. The most frequently used methods, steady as well as unsteady, are described in some detail. Recent developments aiming at improvönent and extension of the range of applicability are reviewed. The use of panel methods for the determination of stability derivatives is discussed....

Investigation of the unsteady airloads on wing-store configurations in subsonic flow

A description and results are given of an extensive research program set up to determine the unsteady aerodynamic loading on oscillating wing-store configurations. It is shown that the tools developed in the course of the program allow for a more accurate prediction of the unsteady airforces introduced by wing mounted stores.

The use of panel methods for stability derivatives

The possibilities of panel methods for computing aerodynamic stability derivates are reviewed. Emphasis is put on unsteady panel methods, results of which are compared with experimental data.

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...

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 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,...

Unsteady airloads on a harmonically pitching wing with external store

Results are presented of a wind-tunnel investigation carried out on a harmonically pitching fighter-type wing with and without an external store (air to air missile). In this test detailed steady and unsteady pressure distributions were measured on the wing, while also the aerodynamic loads on the store were obtained. The Mach number ranged from...

Comparative measurements in four European wind tunnels of the unsteady pressures on an oscillating model (The Nora Experiments)

To obtain experience of the influence of tunnel wall interference on flutter and other unsteady tests in transonic wind tunnels, a programme of oscillatory pressure measurements was repeated in four tunnels namely: 3 ft RAE Bedford 82 ONERA Modane, 1 m DFVLR Göttingen HST NLR Amsterdam. These tunnels differ in the size of working section, their...

Report 88-25 (Reviewed) TUD Faculty of Technical Mathematics and Informatics Heuristic reasoning

In this paper a model for heuristic reasoning with uncertain knowledge is presented. This model is a generalisation of the approach proposed by Clancey (Cla-84, Cla-85). We offer a clear semantics for the model, showing that the heuristic reasoning process can be given a clear probabilistic interpretation.

How to reason with uncertain knowledge

In this paper two kinds of uncertainty, general and specific uncertainty, are distinguished. General uncertainty denotes an uncertainty about which objects of a class belong to a relation. Sentences in which it occurs can be view as describing incomplete knowledge. An example of such a sentence is: "Most humans have brown eyes". Specific...

What is on the machine's mind? Models for reasoning with incomplete and uncertain knowledge

In this thesis, which consists of two parts, two different subjects are discussed. In the first part of the thesis a logic for reasoning with inconsistent knowledge will be described. The second part of the thesis contains a proposal for to view a reasoning process as a process of constructing a partial model of the world we are reasoning about....