RU-2861571-C1 - AIRCRAFT AIR INTAKE DEVICE SUPPLYING AIR TO BYPASS TURBOJET ENGINE

RU2861571C1RU 2861571 C1RU2861571 C1RU 2861571C1RU-2861571-C1

Abstract

FIELD: aviation. SUBSTANCE: proposed is an aircraft air intake device supplying air to a bypass turbojet engine, which includes a system for protecting the engine from foreign objects entering its inner air circuit. However, due to the insufficient efficiency of the engine protection system, the aircraft air intake device is also proposed to be equipped with a protection system designed to work together with the engine protection system and increase the overall efficiency of air purification from foreign objects to the required level. The system consists of a protective screen and a control mechanism that installs the protective screen in the air intake device tunnel in the working and retracted positions. EFFECT: possibility for solving structural and layout problems, maintaining the characteristics of the power plant at the proper level, ensuring reliability and operational manufacturability of the aircraft. 1 cl, 3 dwg

Inventors

SITNITSKIJ YURIJ YAKOVLEVICH
Sitnitskij Aleksej YUrevich

Dates

Publication Date: 20260506
Application Date: 20251106

Claims (1)

An aircraft air intake device that supplies air to a bypass turbojet engine that includes a system to protect the engine from foreign objects entering its internal circuit, which has an insufficient level of efficiency in cleaning the air from foreign objects, characterized in that the aircraft air intake device also includes a protection system designed to work together with the engine protection system, to obtain a total effective level of air purification and protection from foreign objects entering the internal circuit of the engine, said system consists of a protective screen and a control mechanism that installs the protective screen in the air intake tunnel in the working and retracted position, in the working position, when there are foreign objects in the air flow, the protective screen is installed in the space between the inlet opening of the air intake tunnel and the mating surface of the engine, blocking part of the flow zone in the tunnel, from which the air flow with foreign objects enters the hub zone of the fan stage, in its lower half, where the bulk of foreign objects moves objects entering the inner circuit of the engine, at the same time the protective valve is located in the air flow zone through which foreign objects enter the inner half of the hub zone of the fan stage, in which the engine protection system has the lowest efficiency of protection against foreign objects, in the absence of foreign objects in the air flow, the protective screen is removed from the flow by the control mechanism and placed in a niche made in the side wall of the air intake tunnel, the protective screen is a louvered grille consisting of several separating profiles, in each of which a reflective surface is made in the front part, facing at an angle towards the oncoming air flow, the rear part of the separating profile is made in the form of a tapering fairing, with a bend in the tail section, the separating profiles are attached to the longitudinal elements of the grille with a gap from each other and form between themselves a system of echeloned curved flow channels through which air passes into the zone of the inner circuit of the engine, while the relative cross-sectional area of the air flow blocked by the protective screen is within 15-35% of the total cross-sectional area of the flow following the inner circuit before entering the fan stage of the engine, the geometry of the separating profiles of the louvered grille, their relative position when the grille is in the operating position is such that the total area of the flow sections of the grille flow channels is equivalent to the midsection area of the protective screen, the geometry of each flow channel in the grille and their echeloned arrangement along the air flow movement predetermines the air flow to perform a wave-like motion when passing through the channels, which does not cause consequences in the form of extensive vortex formation, increased energy consumption and a large value of the local hydraulic resistance coefficient, the total midsection area of the reflecting surfaces of the separating profiles in the grille in its operating position is also equivalent to the midsection area of the flow channel blocked by the protective screen, the clear gap in the direction of the axis of the air intake tunnel between adjacent grille profiles is made equal to either zero or has some overlap.

Description

The invention pertains to the field of aviation, and more specifically to a device for protecting turbojet engines (TJE) 1 ( 1 Abbreviations are explained in the text; a full list of abbreviations is also provided on page 10.) from the ingress of foreign objects (FO), in particular, to air intake devices for bypass turbojet engines (TJE) that clean the air entering the engine's internal circuit from foreign objects. Currently, this type of engine is widely used in operation on civil and military aircraft. Furthermore, the invention can be used on ground-based gas turbine units (GTU), where there is also a frequent need to protect the engine from the ingress of foreign objects into its gas-air tract (GAT). A feature of the layout of many modern aircraft is the low (close to the ground surface) location of the engine under the wing of the aircraft, which leads to a high frequency of foreign objects (FO) entering the engine main turbine through the aircraft air intake, resulting in engine failure due to the destruction of compressor blades. As a result, the reliability of both engines and aircraft, flight safety, combat readiness, mobility, and flight regularity are reduced. Premature engine removals are common due to compressor blade damage that cannot be repaired under operating conditions. Furthermore, operational performance indicators are significantly deteriorating—engine maintenance volumes, aircraft downtime, and aircraft operating costs are increasing. The efficiency and profitability of aircraft use are sharply reduced. In modern aircraft engine building practice, design solutions are known aimed at engine self-protection, reducing the incidence of ingress of PP into the turbofan core. Typically, this is achieved by using the process of inertial separation of PP during their interaction with the fan blades and compressor booster stages. In this process, some of the PP moving along the fan hub zone 2(2 The fan hub zone is the zone of the fan stage from which air enters the engine core) moves to the periphery of the core channel and is discharged into the engine's outer circuit through the axial gap between the fan impeller (RI) blades and the inlet guide vane (IGV) of the core—outward from the circuit separator. The other part of the PP, remaining in the internal circuit, is separated by a group of subsequent booster stages of the low-pressure compressor (LPC), moves to the periphery of the flow channel, and after the last stage is discharged into the bypass channel and air extraction into the external circuit or into the surrounding air space. The described design solutions are used in various types of foreign and domestic turbofan engines [1, 2]. They significantly reduce the incidence of propellant gas entering the engine's main circuit. However, the problem of reducing the incidence of propellant gas entering the turbofan engine's internal combustion engine circuit, as demonstrated by actual operating experience, has not yet been fully resolved and remains relevant for many engine types, especially older designs, such as the domestic PS-90A engine used on the IL-96, IL-76, TU-204, and TU-214 aircraft. The main reasons for the insufficient purification of air entering the engine's high-pressure compressor (HPC) are the low efficiency of the PP separation process in the hub zone of the fan stage, especially in its inner half, as well as the process of removing separated PP from the last booster stage of the low-pressure compressor. The above conclusions are confirmed by a patent [3], which indicates the presence of similar problems in air purification in a gas turbine unit manufactured as a conversion of the PS-90A aircraft engine. However, implementing known solutions [4, 5, 6] into the design of the PS-90A engine or at least somehow improving the existing air purification system in the engine turned out to be practically impossible due to the large volume of work, long lead times, and high economic costs with an uncertain risky outcome. The search for a solution to the problem of increasing the efficiency of cleaning the air moving into the internal engine circuit continued in the direction of the possibility of introducing an additional cleaning system into the aircraft power plant (PP), duplicating the operation of the engine system and not adding any unacceptable harmful consequences for the engine and the aircraft. The final result of the search for analogs among domestic and foreign aircraft air intake devices with protection of the internal contour of turbofan engines can be found in the quotation from the review [7] p. 29 3 ( 3 From the Boeing report on the development of a version of the Boeing 737 aircraft intended for operation from airfields with gravel surfaces, “Various designs of engine protective devices were studied, such as retractable screens, protected entrance, gravel traps and others. It was concluded that the problems of loss of engine thrust, heating of the device, pressure