RU67258U1 - INSTALLATION FOR AERODYNAMIC TESTS OF THE MODEL OF THE AIR INTAKE OF THE ENGINE OF THE AIRCRAFT ENGINE (OPTIONS) - Google Patents

Abstract

The utility model relates to the field of aerodynamic tests, in particular, to installations for studying the conditions of vortex formation and the ingress of foreign particles into the air intake of an aircraft. Installation for aerodynamic testing of the model of the air intake of an aircraft engine, containing a model of a nacelle with an air intake, a system that provides air leakage through the air intake, a fixed screen simulating a runway, a container located under the inlet of the air intake, with a substance that is affected by the vortex flow, arising under the air intake, and the storage device installed in the output part of the model, while the installation is equipped with a fan An object simulating an external controlled air flow of different speed, direction and degree of unevenness for the model, solid particles with a shape and size selected from similar conditions, coated with fluorescent paint are placed in the container, a layer of the same uncoated solid particles are laid around the container, forming together with solid particles in the tank, the common surface simulating the surface of the runway, in addition, the installation is equipped with a light source that provides the occurrence of fluorescence effect, and by means of photo and / or video recording of the trajectory of luminous particles, moreover, washed river sand is used as solid particles,

sifted on calibrating sieves. According to the second embodiment of the installation, solid particles with a shape and size selected from a similar condition, coated with fluorescent paint, are poured directly onto the surface of the screen without using a container.

The technical result of using the utility model is to assess the degree of engine protection for the selected layout of the engine nacelle and determine the safe taxiing modes of the aircraft at the aerodrome due to the information on the trajectory of solid particles (sand) under various engine operating conditions and various external conditions (crosswind), and also information about the trajectory of the particles after they enter the air intake channel and the place of their collision with the inner surface of the model. In addition, the result is a picture of the flow between the screen and the entrance to the air intake, the nature of the spread of sand and the area and location of the sand capture zone from the surface, the ratio of the mass of sand falling into the air intake and the mass of sand flying around the surface of the runway, in in particular, depending on the size, mass and shape of the particles.

Description

The technical field to which the utility model relates.

The utility model relates to the field of aerodynamic tests, in particular, to installations for studying the conditions of vortex formation and the ingress of foreign particles into the air intake of an aircraft.

State of the art

There are various devices for aerodynamic testing, which are analogues of the claimed utility model.

A device for conducting aerodynamic tests is known, which provides visualization of the flow around an aerodynamic object (autosvid. USSR SU 1749742, G01M 9/00, 07.23.1992). The device contains the main electrodes located on the studied surface of the object made with a dielectric coating, connected to the electrodes is a high-voltage pulse current source and means for recording the glow of the discharge channel in the discharge gap between the electrodes. There is an additional initiating electrode made in the form of

placed under a dielectric coating conductor, electrically connected to one of the electrodes.

A device for modeling the volumetric structure of flows in the surface air layer (patent of the Russian Federation RU 1766166, G01M 9/00, 10.27.1995), allowing to visualize the structure of air flows. The visualizing substance is applied to the surface of the model of the test object, which is blown by the air flow, and after the spreading of the visualizing substance, the flow pattern is fixed, the model of the test object, modeled taking into account the terrain, is installed in the working part of the wind tunnel, blowing is carried out in the directions corresponding to the wind rose on terrain of the studied object, and after fixing the pattern of flows in the circulation zones, they are placed and moved in horizontal planes and along the height of the layout, small rods or strings with colored threads or a bunch of threads fixed on them, pre-treated with an antistatic agent, and then smoke streams are blown into the boundary areas of the circulation zones of the stream, while the structure of the air flows is fixed to the film and transferred as vectors to the general plan and axonometric diagram of the object under study . In addition, the layout and its base are made of transparent material.

A known system for studying the behavior of sand and dust particles under the influence of wind (China application CN 162179, G01M 9/00, 06/01/2005). The system includes a velocity source of air flow simulating

winds, test sand and dust, air regulator and pipes. An air regulator is connected through pipes to a source of air flow, and each of the pipes is equipped with a valve to control flow, flow rate and pressure. An air regulator is also used to control temperature and humidity. The system can be used for experiments with sand and dust to establish their interaction with a vehicle (aircraft, tank, etc.)

Other devices for aerodynamic testing are also known (US 3835703, JP 62005145, JP 2002022597, JP 8054334, DE 19902573, US 6276217).

Known analogues are designed to visualize turbulent and / or laminar flows in liquids or a gaseous medium, and are not intended to study the behavior of sand particles when interacting with the model of the air intake of an aircraft engine located above the surface of the runway.

The closest analogue of the claimed technical solution is the installation for aerodynamic testing of the model of the air intake of the aircraft engine, used to determine the intensity of the vortex (vortices) under the air intake (patent of the Russian Federation RU 2252404, G01M 9/00, 05.20.2005).

The installation according to patent RU 2252404 contains a control panel, an electric motor, a blower in the form of a centrifugal compressor, an air discharge pipe with a damper, a suction pipe

air damper, diffuser, U-shaped differential pressure gauge for measuring air flow in the air intake duct, lighting equipment. A screen is installed under the air intake (runway surface simulator). The dimensions of the air intake are selected from the condition of achieving a speed equal to the speed in the real air intake of the aircraft.

Installation according to patent RU 2252404 works as follows.

After the motor spins up, the shutters are smoothly opened. The blower enters the operating mode with a given air flow rate in the air intake, which is determined by the U-shaped differential pressure gauge. A vortex (vortices) is formed under the air intake, which carries a certain mass of liquid from the supply vessel into the channel. A change in the liquid level in the supply vessel through the central opening leads to a change in the liquid level in the storage device. The difference in liquid level in the storage device is measured, then the area of the supply vessel at the level of the remaining liquid is determined. After that, the volume V _{B of the} sucked-in liquid is calculated by the air intake from the supply vessel for a certain time interval t. After conducting a series of measurements and determining the characteristics for an air intake of one shape, an air intake of another shape is installed, then the complex of measurements is repeated. Installation allows you to quantify

the intensity of the vortex (vortices) under the air intake for a certain time interval t.

The closest analogue, as its name implies, allows you to determine the vortex intensity, and is not intended to assess the behavior of solid particles under the air intake under various engine operating conditions and various external conditions, as well as the behavior of sand particles after they enter the air intake channel.

Utility Model Essence

The problem solved by the utility model is the elimination of these shortcomings, providing a detailed study of vortex formation in front of the air intake, including determining the trajectory of sand particles inside the air intake, in particular, in the zone of reflection from the conical surface of the coke, estimating the total mass of sand interacting with the vortex, and also determining the amount sand captured by the air intake and the mass of sand flying over the surface of the runway, including depending on the size, weight and shape of the hour tits.

The study of particle suction from the surface of the runway is necessary to obtain recommendations when designing air intake devices. An important condition for such studies is the selection of the size, density and shape of the particles used as an object of absorption for the tested model

air intake of predetermined geometric dimensions at different distances to the underlying surface.

The task for the first embodiment of the installation is solved due to the fact that it contains a model of a nacelle with an air intake, a system that provides air leakage through the air intake, a fixed screen that simulates the runway, a container located under the inlet of the air intake with the substance that affects the vortex flow arising under the air intake, and the storage device installed in the output part of the model. Distinctive features of the claimed device is that it is equipped with a fan installation that simulates an external adjustable air flow for the model of various speeds, directions and degrees of unevenness, solid particles with a shape and size selected from similar conditions, coated with fluorescent paint are placed in the container, a layer is laid around the container of the same uncoated solid particles forming together with the solid particles in the tank a common surface simulating the surface of the runway, additional itelno installation is provided with a light source, providing the appearance of the fluorescence effect, and by means of photo and / or video fixation trajectory of luminous particles.

The second embodiment of the installation is characterized in that it contains a model of a nacelle with an air intake, a system that allows air to flow through the air intake, stationary

a screen simulating a runway, a substance located under the inlet of the air intake, which is affected by the vortex flow arising under the air intake, and a storage device installed in the output of the model, while the unit is equipped with a fan installation that simulates an external adjustable air flow for the model of different the speed, direction and degree of unevenness, as a substance that is affected by the vortex flow, used solid particles with selected from the conditions I am similar in shape and size, coated with fluorescent paint, in addition, the installation is equipped with a light source that provides the occurrence of the fluorescence effect, and means of photo and / or video recording of the trajectory of luminous particles.

As solid particles, washed river sand sifted on calibrated sieves is used in the experiment.

Means of video recording the trajectory of luminous particles is made in the form of a digital video recording system associated with a personal computer.

To fix the trajectories of luminous particles inside the model, a transparent window is made on its lateral surface.

To test the model of the air intake of the dual-circuit engine, the model is made with a shell simulating the separation of the external and internal circuit of the engine, a separation grid is installed at the output of each circuit, which delays the one that got into the corresponding circuit

sand and its directing into the corresponding storage device - sand collector.

The technical result of using the utility model is the ability to assess the degree of engine protection for the selected layout of the engine nacelle and the ability to determine safe modes of taxiing the aircraft at the aerodrome by visualizing the behavior of particulate matter (sand) under various engine operating conditions and various external conditions (crosswind) as well as the behavior of particles after they enter the air intake channel, fixing the place of impact of sand particles with the inner surface of the model. In addition, the result provided by the utility model is to obtain a flow pattern between the screen and the entrance to the air intake, which is very important for studying the process of vortex formation and capture of sand particles, obtaining a quantitative characteristic of the mass of sand captured by the air intake (with a dual-circuit engine, with separation along the contours), as well as an assessment (depending on the regimes) of the nature of the spread of sand and the area and location of the zone of capture of sand from the surface, determining the ratio of the mass of sand falling into the the air intake, and the mass of sand flying over the surface of the runway, in particular, depending on the size, mass and shape of the particles.

The proposed installation, in contrast to the previously known ones, allows us to study, along with the vortex formation process in front of the air intake, the trajectory of sand particles outside and inside the air intake, taking into account

modeling their mass and geometric shape, in particular, the trajectory of particles in their reflection zone from the conical surface of the coca. In addition, it is possible to determine how much sand is generally captured by the vortex flow, i.e. rises from the surface of the runway of the runway, and which part of this amount is dangerous for the aircraft, i.e. how much sand enters directly into the air intake duct.

Visualization of the movement of sand particles inside the air intake is possible using a special window made on the side surface of the model, or when observing the behavior of particles through the input channel of the air intake model.

The study of fluxes using grains of sand coated with a special fluorescent paint and the light source used to illuminate grains of sand during an experiment is known from Japanese patent application JP 5297014, as well as US Pat. No. 6,276,217, which describes an apparatus that implements a method for visualizing a flux in which particles coated with a fluorescent composition illuminate them to create conditions for fluorescence, while the particles are prepared by impregnating quartz (SiO ₂ ) with a liquid fluorescent substance, then dried particles are used.

However, this setup is intended only for the study of fluid flow lines, and cannot be used to study the behavior of sand particles under the influence of the vortex gas motion. Particles coated

fluorescent composition, forced into the fluid stream in order to track the nature of its movement. The task of modeling the behavior of particles in the flow was not solved. Unlike the known installation in the claimed utility model, coated with a fluorescent composition, are not forced into the stream, but are involved in movement when a vortex occurs during operation of the air intake, which allows one to judge not only the nature of the vortex movement, but also the behavior of solid particles under the influence of the vortex .

Brief Description of the Drawings

The utility model is illustrated by the following materials:

figure 1, 2 is a General diagram of the installation,

figure 3 - diagram of the model,

4, 5, 6 - location on the model of a transparent window,

7, 8 - a fragment of a video recording of the experiment (the path of the expansion of particles coated with a fluorescent composition),

Fig.9 - the trajectory of the particles coated with a fluorescent composition inside the air intake,

figure 10 - layout of recording equipment.

Utility Model Implementation

Installation for aerodynamic testing of the model of the air intake of the aircraft engine contains:

- a model of a nacelle with an air intake 1, intended for testing in a wind tunnel above a fixed screen simulating a runway;

- cook engine 2;

- shell 3, simulating the separation of the external and internal contour of the engine;

- separation grid 4 at the output of the external circuit of the engine, delaying the sand trapped in the external circuit;

- sand collector 5 of the external circuit, into which sand is sent from the separation grid 4;

- separation grid 6 at the output of the internal circuit of the engine, delaying the sand that has fallen into the internal circuit;

- sand collector 7 of the inner circuit, into which sand is sent from the separation grid 6;

- an ejector system providing air leakage through the air intake;

- a fan unit 9, simulating an external air flow (wind) for the model of various speeds, directions and varying degrees of unevenness;

- screen 10 simulating the surface of the runway;

- a container 11 located at the entrance to the air intake (for the first embodiment of the installation) with solid particles (sand) placed in it and coated with a fluorescent composition, surface

which is at the simulator level the surface of the runway (hereinafter runway);

- a light source (not shown) providing the occurrence of a fluorescence effect;

- means of photo and / or video recording of the experiment, providing the ability to record and process the received image on a personal computer (not shown).

According to the results of a statistical analysis of particles collected on the surface of a full-scale runway, the most common particles are 10-20 mm in size. The relatively large particle size largely determines the possible methods for their modeling (geometric, mass similarity), studying their spatial distribution and the nature of the movement.

An example implementation of a utility model.

For a model made on a scale of 1: 6, particles of washed river sand sized 2 ... 3 mm sifted on special sieves were selected according to the laws of similarity. Before the experiment, fluorescent paint was applied to a part of the volume of sand. Sand covered with fluorescent paint, in principle, can be poured directly onto the screen at the entrance to the air intake. However, for a quantitative assessment of the mass of sand captured by the vortex flow, it is advisable to pre-weighed a portion of the sand covered with fluorescent paint, pour it into the tank installed on the screen simulating the runway. The rest

it is advisable to fill the screen surface to the same level with uncoated sand, since the glow of grains of sand against a dark background of ordinary sand looks contrasting, and the paths of expansion of fluorescent grains of sand are clearly visible. You can not use ordinary sand, but cover the screen with matte dark paint. If a container is used, it must be installed in a niche of the screen in order to position the surface of sand at the level of the screen.

The internal surfaces of the model — coke, shells — are coated with a matte dark paint in order to minimize the degree of illumination of the image and to provide the ability to visualize the trajectory of fluorescent grains of sand and the places where they collide with the internal parts of the model.

Dynamic visualization of the process of the formation of vortex structures, the development of the process of particle capture and the evolution of their motion in the region between the screen and the air intake model can be captured by filming or digital video recording systems. Despite the relatively low speed of video recording, tracks that fix the trajectory of particles coated with fluorescent paint and illuminated by a light source that causes fluorescence clearly show the direction of development of the process, characteristic moments of its restructuring. When using digital video recording systems, the image was recorded on a personal computer to which a digital video camera was connected.

Particle movement can also be visualized by photographing or filming from a side angle from a distance of about 1.5 m with appropriate illumination of sand particles by a light source to obtain a fluorescence effect against a dark background.

When photographing images of tracks have a clearly defined length (depending on shutter speed). The prevailing particle paths were determined by the nature of the direction of the set of images of the tracks. In addition, the choice of exposure time made it possible to set the track length fixed by the camera (a fixed image of a segment of the particle trajectory). By analyzing the projection of tracks onto the image plane, we obtained results indicating the corresponding components of the direction of motion and particle velocity.

In order to obtain an image allowing these conclusions to be drawn, it is necessary to ensure the minimum reflective properties of the channel walls and other structural elements of the air intake model. This was achieved by using matte black paint to cover the interior surfaces of the model (background). The green glow of the particles against a dark background (using an ultraviolet light source) was very contrasting and made it possible to obtain good experimental material for further processing.

When installing a recording device (photo and / or video camera) in a different perspective, particle tracks were received at the entrance to

air intake, including moments associated with the reflection of particles from the Coca model.

An ultraviolet source or a pulsed laser with a cylindrical focusing system was used as a light source, which ensures a high brightness of the particles in a narrow (in width) observation zone with minimal contact of the laser light with the side walls of the channel. In this case, only the coke remained in the zone of the light beam. It is also possible to use laser sources of continuous radiation, which makes it possible to obtain a higher probability of obtaining a track image in the frame compared to a pulsed laser.

The study of the particle suction process and their movement in the inlet of the air intake was carried out in two zones:

- in the area of interaction of the air vortex created as a result of the process of suction of air into the air intake, with the surface on which there were particles of sand covered with fluorescent paint;

- inside the air intake.

The tests were carried out at an angle of blowing the model with an external air flow created by the fan unit 9, from 0 ° to 90 ° at various air flow rates through the model’s air intake and various external flow rates.

Visualization of the movement of sand particles inside the air intake was carried out through a transparent window on the side surface of the model, to which a photo or video camera adjoined, and through the entrance

air intake with the corresponding aspect of the camera or camera (at an angle to the longitudinal axis of the model).

As a result of the experiments, the chaotic nature of the expansion of particles in the "fountain" in front of the air intake was established. The trajectories of particles flying into the air intake are distributed over a wide area, and not in a narrow beam. Video recording recorded the pulsating nature of the "fountain" of grains of sand. This allowed us to conclude that the vortex trajectory is unstable within the crater created by it. In the photo inside the channel, individual bright points are visible - on the walls of the channel and on the edge of the shell separating the external and internal contours. These are places of impact with fluorescent sand particles.

It was established that the dependence of the vortex intensity on the flow rate of air flowing into the air intake is nonmonotonic. Video data and the results of weighing sand that fell into the sand collectors confirmed this result. A whirlwind, rotating around its axis, simultaneously moves along a closed curve that is close in shape to a circle, "sucking out" sand from a restricted area. This area is less than the width of the air intake in width. Part of the colored sand enters the air intake and a significantly larger part of it is scattered randomly on the screen surface. This is clearly demonstrated by the photographs taken, on which, against the background of ordinary sand, fluorescent grains of sand thrown out of the tank are clearly visible.

The separate weighing of sand that got into the sand collectors after the experiment showed that due to the separating role of the coca, the amount of sand that got into the inner loop is several times less than the amount of sand that got into the outer loop.

Comparison of the total mass of sand falling into both sand collectors with the mass of sand remaining in the tank allows us to determine the ratio of the amount of sand raised from the surface of the screen to the amount of sand trapped in the air intake.

The results obtained make it possible to obtain a qualitative and quantitative characteristic of the interaction of the air intake and solid particles located on the surface of the runway. The data obtained can be used in the design of air intake devices.

Claims (8)

1. Installation for aerodynamic testing of the model of the air intake of the engine of the aircraft, containing a model of a nacelle with an air intake, a system that provides air leakage through the air intake, a fixed screen that simulates the runway, a container located under the inlet of the air intake, with the substance that is affected by the vortex the flow arising under the air intake and the storage device installed in the output part of the model, characterized in that it is equipped with a fan a set-up that imitates an external adjustable air flow of different speed, direction and degree of unevenness for the model, solid particles with a shape and size selected from similar conditions, coated with fluorescent paint are placed in the container, a layer of the same uncoated solid particles are laid around the container, forming together with solid particles in the tank, the common surface simulating the surface of the runway, in addition, the installation is equipped with a light source that provides the occurrence of the fluorescence effect tion, and by means of photo and / or video recording of the trajectory of luminous particles, moreover, washed river sand sifted on calibrating sieves is used as solid particles. 2. Installation according to claim 1, characterized in that a digital video recording system connected to a personal computer is used as a means of video recording the trajectory of luminous particles. 3. Installation according to claim 1, characterized in that in order to fix the trajectories of luminous particles inside the model, a transparent window is made on its lateral surface. 4. Installation according to claim 2 or 3, characterized in that for testing the model of the air intake of the dual-circuit engine, the model is made with a shell simulating the separation of the external and internal circuit of the engine, a separation grid is installed at the output of each circuit, which traps sand and guides it into the corresponding storage device - a sand collector. 5. Installation for aerodynamic testing of the model of the air intake of the engine of the aircraft, containing a model of a nacelle with an air intake, a system that provides air leakage through the air intake, a fixed screen that simulates the runway located under the inlet of the air intake substance, which is affected by the vortex flow arising under air intake, and a storage device installed in the output part of the model, characterized in that it is equipped with a fan installation, which protects the model with an external adjustable air flow of different speed, direction and degree of unevenness, as a substance that is affected by the vortex flow, solid particles with a shape and size selected from the conditions of similarity, coated with fluorescent paint are used, the unit is additionally equipped with a light source that provides the effect fluorescence, and by means of photo and / or video recording of the trajectory of luminous particles, moreover, washed river sand is used as solid particles, sifted on calibrating sieves. 6. Installation according to claim 5, characterized in that a digital video recording system connected to a personal computer is used as a means of video recording the trajectory of luminous particles. 7. Installation according to claim 5, characterized in that a transparent window is made on its side surface to ensure fixation of the trajectories of luminous particles inside the model. 8. Installation according to claim 6 or 7, characterized in that for testing the model of the air intake of the dual-circuit engine, the model is made with a shell simulating the separation of the external and internal circuit of the engine, a separation grid is installed at the output of each circuit, which traps sand and guides it into the corresponding storage device - a sand collector.