Aerodynamic model of a supersonic aircraft with a dynamically similar model of the forward fuselage

Abstract

The utility model relates to the field of aviation engineering and concerns, in particular, the solution of problems of designing and manufacturing aerodynamic and dynamically similar models for experimental studies of the aerodynamics and aeroelasticity of aircraft (AC) in wind tunnels (WT).An aerodynamic model of a supersonic aircraft with a dynamically similar model of the forward fuselage, which, when assembled, represents a single structure of a closed aerodynamic shape, containing a rigid aerodynamic model of the central and tail sections of the aircraft, equipped with units that ensure the possibility of conducting tests at high angles of attack, and a dynamically similar model of the forward fuselage, rigidly attached to the aerodynamic model of the aircraft and including: a power core simulating the rigidities of the full-scale structure, fuselage sections attached to the power core and bearing aerodynamic loads, loads attached to the power core and simulating mass-inertial characteristics.

Description

[0001] The utility model relates to the field of aviation engineering and concerns, in particular, the solution of problems of designing and manufacturing aerodynamic and dynamic-like models for experimental studies of aerodynamics and aeroelasticity of aircraft (AC) in wind tunnels (WT).

[0002] The shortcoming and complexity of obtaining calculation data on the influence of the elasticity of the extended nose section of the fuselage of a prospective SGS on dynamic and aerodynamic loads determines the advisability of obtaining the parameters of the dynamic behavior of the nose section of the fuselage under conditions of unsteady flow in takeoff and landing modes and in wind gusts for the validation of calculation models using experimental methods.

[0003] It is known that no studies have yet been conducted on the effect of the elasticity of the extended forward fuselage on dynamic and aerodynamic loads. This is due, among other things, to the need to ensure similarity in the dynamic behavior of the model's forward fuselage to that of the actual structure, which cannot be achieved with traditional aerodynamic models.

[0004] Aerodynamic models (weighted and drained) manufactured by milling are known (see S.M. Gorlin, I.N. Slezinger. Aeromechanical Measurements, Moscow, 1964, p. 552). This design and manufacturing method ensures high-precision reproduction of aircraft contours using weighted rigid models. Disadvantages of these models include the inability to reproduce rigidity and mass-inertial characteristics and the lack of free internal volumes, which precludes research into the influence of the dynamic and elastic behavior of aircraft structural elements on the aircraft's aerodynamic characteristics.

[0005] An elastic-like model with an elastic frame is known (see S.M. Gorlin, I.N. Slezinger. Aeromechanical measurements, Moscow, 1964, Figs. 12-22), in which the aerodynamic contours are made by processing either balsa or foam plastic glued to an elastic frame.

[0006] A disadvantage of this type of model is the difficulty in achieving acceptable accuracy in reproducing the external contours and, especially, the rigidity characteristics of the model due to the wide variation in the stiffness of the foam (balsa), adhesive, and the outer layer of fabric required to prevent erosion of the model's outer surface during wind tunnel testing. Typically, in such models, designed primarily for weight-based studies of static aeroelasticity, drainage (and strain-gauging) for determining distributed loads is difficult due to the lack of cavities within the model. Furthermore, flutter studies are difficult due to the inevitable overweighting of the model.

[0007] A structurally similar model is known (see S.M. Gorlin, I.N. Slezinger. Aeromechanical Measurements, Moscow, 1964, pp. 620-625, Fig. 12-2), in which the geometric contours are reproduced using a thin skin, and the rigidity characteristics are modeled both by the skin and by the longitudinal and transverse frame structure. The disadvantage of such a complex, labor-intensive model in design and manufacture is its relatively low strength, which does not allow the use of this type of model for a comprehensive study of aeroelastic phenomena, in particular, for determining loads at high angles of attack and high dynamic pressures.

[0008] The proposed utility model solves the problem of conducting tests of an aerodynamic model in a wind tunnel to assess the influence of the elasticity of the extended nose section of the fuselage on dynamic and aerodynamic loads under conditions of non-stationary flow during takeoff and landing modes and during wind gusts.

[0009] The technical result is to ensure universality in terms of modeling various bow parts of a full-scale design, similar in dimensional characteristics and differing in mass-inertial and rigidity characteristics.

[0010] The solution to the stated problem and the technical result are achieved by the fact that the aerodynamic model of a supersonic aircraft with a dynamically similar model of the nose of the fuselage is, when assembled, a single structure of a closed aerodynamic shape, containing a rigid aerodynamic model of the central and tail sections of the aircraft, equipped with units that provide the possibility of conducting tests at high angles of attack, and a dynamically similar model of the nose of the fuselage, rigidly fixed to the aerodynamic model of the aircraft and including: a power core simulating the rigidity of the full-scale structure, fuselage sections fixed to the power core and perceiving aerodynamic loads, loads fixed to the power core and simulating mass-inertial characteristics.

[0011] The utility model is illustrated in Fig. 1, which shows an aerodynamic model of a supersonic aircraft with a dynamically similar model of the nose section of the fuselage in assembly.

[0012] An aerodynamic model of an aircraft is an aerodynamically and geometrically similar model of a natural object.

[0013] A dynamically similar aircraft model is a model created in accordance with the law of dynamic similarity and used in the study of flutter and other aeroelastic phenomena.

[0014] Fig. 2 shows the design diagram of the dynamic-like model of the fuselage nose.

[0015] Fig. 3 shows the structural elements of the dynamic-like model of the fuselage nose.

[0016] The power core 1, predominantly made in the form of a thin-walled rectangular section made of polymer composite materials, is rigidly attached to the central section of the aircraft aerodynamic model by means of a bolted connection. Local platforms for attaching the sections of the forward fuselage are formed on the core, spaced along the length. The plastic sections 2, with the exception of the first section 6, have a length of no more than 10-25% of the length of the forward section and are designed as shells, the outer surface of which forms the outer surface of the forward fuselage of the model. Sections 2 are divided into two parts by a horizontal plane passing through the axis of the power core 1. The upper part is attached to the lower part by means of a screw connection. Sections 2 are reinforced by cross members (frames) of annular shape 8, located in the area of ​​the end sections of the fuselage.Compartments 2 are mounted on the power core 1 by means of nodes 5, located and secured in the central portions of the lower sections of the compartments. These nodes transmit aerodynamic loads from the outer surfaces of compartments 2 to the power core 1. Node 5 may be implemented, for example, as a terminal clamp. The first compartment 6 is made of a single piece of plastic, non-detachable, no more than 3-5% of the nose section length, and is rigidly attached to the end portion of the power core 1 in the area of ​​the model's nose section by any known method. To prevent the compartments from touching during vibrations of the dynamically similar model of the fuselage nose section during testing, a gap 7 of approximately 3-7 mm is provided between the end portions of the fuselage compartments.

[0017] Weights 3, predominantly cylindrical in shape, are positioned symmetrically relative to the model's axis of symmetry. They are made of high-density metals and are rigidly attached to the power core in the free spaces of compartments 2 via suspension units 4. Suspension unit 4 may be implemented, for example, as a terminal clamp. The position of weights 3 can be changed by moving and securing suspension units 4 along the axis of power core 1 to provide various mass-inertial configurations of the model, as specified by the test conditions.

[0018] The utility model operates as follows: initially, a rigid aerodynamic model consisting of the nose, center, and tail sections of the aircraft is tested; the data obtained from the test results are defined as the initial data. Next, a dynamically similar model of the nose section is assembled in the following order: the lower sections of the compartments are mounted on the load-bearing element using suspension units in accordance with the required mass-inertial configurations of the model, weights are installed and secured, the rigid nose section is dismantled, and, in its place, the dynamically similar model of the nose section is installed using a bolted connection, the upper sections of the compartments are installed on the lower sections and secured using a screw connection. The load-bearing elements can be equipped with sensors, the routes to which are laid along the load-bearing core of the model (not shown in the figures). After assembly, the model is subject to control frequency tests.Wind tunnel tests are then conducted, allowing for rapid adjustments to the mass-inertial configuration of the dynamically similar nose cone model between launches by adjusting the position of the weights. The resulting test results are compared with the original data.

[0019] This utility model enables the fabrication and testing of models in subsonic wind tunnels to assess the effect of the elasticity of the extended forward fuselage on dynamic and aerodynamic loads under unsteady flow conditions during takeoff and landing and during wind gusts. Versatility, namely the ability to conduct exploratory parametric studies within a single model to optimally distribute stiffness and structural weight within the forward fuselage, is achieved through the design features of a supersonic aircraft aerodynamic model with a dynamically similar forward fuselage model. Furthermore, using this model reduces production costs and shortens the time required to prepare and maintain the wind tunnel experiment.

[0020] A prototype model was manufactured at FAU TsAGI, which confirmed the above technical result.

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