Influences mathematical model of a condition of a flow on aerodynamic characteristics of the maneuverable aircraft

Aerodynamics and heat-exchange processes in flying vehicles


Аuthors

Popov S. A.*, Gondarenko Y. A.**

Air force academy named after professor N.E. Zhukovskii and Yu.A. Gagarin, 54a, Starykh bol'shevikov, Voronezh, 394064, Russia

*e-mail: popov_ser@mail.ru
**e-mail: vip.kuban777@mail.ru

Abstract

Purpose of the work is investigate of the influence of a condition of a tear-off and vortex flow around a maneuvering aircraft with external suspension on his aerodynamic characteristics.

Methods of the work are the analysis and numerical experiment.

Results of the work. Currently the of a condition of a tear-off and vortex flow in the mathematical model of the aircraft is taken into account by entering the internal variable x. The behavior of this variable can be described by the equation:

, (1)

where τ1, τ2 — time constants, caused by a lag effect of the processes of development of separated flow around or recovery non-separable flow.

In the simplest case, the variable x may be regarded as the relative coordinate of the point of separation of flow from the upper airfoil surface or the point of destruction (explosion) of vortices above the upper surface of the wing. For a full layout of the aircraft with the wing of complex shape in plan, including external suspension, a of a condition variable x has a different more complex form and appears in the form of a generalized variable.

It is known that the parameters characterizing the state of a tear-off and vortex flow, can be used:

— coordinate of the point of separation of flow in each section of the streamlined surface;

— number and area zones of separated flow;

— the coordinates of these zones on the streamlined surface;

— parameters characterizing the symmetry (asymmetry) of zones of separated flow on a streamlined surface.

The analysis of the above parameters suggests that they all depend on the location along the wingspan of the points of separation (R) and reattachment (S). The locus of these points for various sections of the wing will determine the position of the lines of of separation (lR) and reattachment (lS). In this case, a generic variable x can be represented by parameters which determine the position of the lines of separation and reattachment.

To determine lines of separation and reattachment with the use of the software Ansys Fluent, the authors investigated the process of flow airflow around the maneuverable aircraft at high angles of attack with various embodiments of external suspension. The results of the research are:

− a field of condition of a tear-off and vortex flow of profiles of a wing and the stabilizator of the maneuverable aircraft airplane with different options of placement of external suspension brackets and without them;

— analysis of the impact properties of the external mounts on the condition of a tear-off and vortex flow around of the maneuverable aircraft;

− analysis of influence of a status of a tear-off and vortex flow on aerodynamic characteristics of the maneuverable airplane;

− a mathematical model of influence of a status of a tear-off and vortex flow on aerodynamic characteristics of the maneuverable airplane with external suspension brackets.

Application area of results. Results of this work can be used in scientific and design organizations engaged in development of aerodynamic configurations maneuverable aircraft and control systems, and also in aviation institute of higher education for educational process improvement.

Conclusions.

Thus, the mathematical model of influence of a status of a tear-off and vortex flow on aerodynamic characteristics of the maneuverable airplane with external suspension brackets includes two-dimensional fields of condition of a flow of profiles of a wing and the stabilizator for different sections to which each point there corresponds a certain value of lift coefficient . Such dependencies allow using known types of interpolation with the required degree of accuracy to calculate the values of aerodynamic characteristics for any arbitrary state of flow, which depends, including the availability of external suspensions. This eventually makes it possible to solve equation (1), in which the dynamic variable x will be used for the data status field of the flow profiles for stationary cases .The result of solving equation (1) will be state field of the flow profiles for non-stationary cases .

Keywords:

aerodynamic characteristics, tear-off and vortex flow, the mathematical model, external suspension brackets

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