RU2406877C2 - Strengthening of fan housing in gas-turbine jet engine - Google Patents

Abstract

FIELD: engines and pumps. ^ SUBSTANCE: as per one version of the design, protection ring and heat-resistant ring are subject to shrinkage fit by being tightened to inner diametre of fan housing; protection ring is where big blades of the fan rotate, and heat-resistant ring is where heated air from return exhaust heats the fan housing. In one example, protection ring is made from superalloy in order to provide additional strength of the fan housing where the fan blades can be opened, thus retaining the fan blade inside the fan housing. Also protection ring can be continued at least to the distance in front of the edge of each fan blade and at least to the distance behind rear edge of each fan blade. Heat-resistant ring is made from titanium or other appropriate material. In addition, one or more stiffener rings can be subject to shrinkage fit by being tightened to outer diametre of the fan housing. Protection ring and stiffener rings can decrease flight weight of the fan housing and reduce the cost of materials, and at the same time they can increase the strength of the fan housing. ^ EFFECT: decreasing the weight of the fan housing at maintaining or improving its strength.

Description

The present invention relates to a method and apparatus for hardening a fan casing in a gas turbine jet engine, respectively, made gas turbine jet engine, a method for its modernization and operation.

In a full-scale test of a gas turbine jet engine, the fan blade is deliberately separated from the sleeve at the maximum engine speed by means of a burst bolt located at the base of the fan blade. This test is used to demonstrate the ability of the engine frame to withstand the impact of a fan blade and withstand the resulting unbalanced forces. This shock is absorbed through vibration, the holding system of the fan housing that surrounds the engine. The fan casing is an element in the holding system of the fan casing and is usually the heaviest component of a gas turbine jet engine due to its size and due to the strength requirements that the fan casing may have for holding purposes. In gas turbine jet engines capable of reverse exhaust, heated air flows back from the combustion chamber to the fan region, increasing the temperature inside the fan housing and causing the temperature of the fan housing to rise. Such high temperatures can be a factor in determining which material the fan enclosure should be made of. Maintaining or reducing the weight of the fan casing while maintaining or improving the strength of the fan casing at the same time, and using fan casing materials that can withstand elevated temperatures of the fan casing, is a clearly demonstrated need in the art. Solutions of this kind are disclosed in the foregoing technical damage in documents GB 2192238, US 5163809, EP 1087105, which can be considered as analogues of the present invention, as well as in documents FR 2574476, US 4878821, EP 1197570, US 388602, EP 1406019 and US 3241813.

Brief Description of the Drawings

Figure 1 depicts a schematic drawing of the General structure of a conventional gas turbine jet engine with a fan casing, usual for the prior art.

Figure 2 depicts a cross section of a forged billet for a fan casing, conventional for the prior art.

FIG. 3 is a cross-sectional view of a forged blank for a fan case for protecting a fan case in an embodiment of the present invention.

Figure 4 depicts a cross section of a machined fan casing having two stiffening rings (Figs. 5A, 5B and 6A, 6B) and a protective ring (Figs. 7A, 7B) that were installed in a hot fit with an interference fit on the fan casing figure 3 in an embodiment of the present invention.

Fig. 5A is a cross-sectional view of a forged billet for a first stiffening ring for a fan casing of Fig. 3 in an embodiment of the present invention.

Fig. 5B depicts the first stiffening ring of Fig. 5A with respect to the place to be hot-seated with an interference fit to the fan case of Fig. 3 in an embodiment of the present invention.

FIG. 6A is a cross-sectional view of a forged blank for a second stiffening ring for the fan case of FIG. 3 in an embodiment of the present invention.

FIG. 6B depicts the second stiffening ring of FIG. 6A at the hot seat fit on the fan housing of FIG. 3 in an embodiment of the present invention.

FIG. 7A is a cross-sectional view of a forged blank for a protective ring for the fan case of FIG. 3 in an embodiment of the present invention.

Fig. 7B depicts the protective ring of Fig. 7A at the site of the hot fit interference fit on the fan case of Fig. 3 in an embodiment of the present invention.

Fig. 8 is a schematic drawing of air flow through a conventional gas turbine jet engine.

9 is a schematic drawing of air flow through a conventional gas turbine jet engine capable of reverse exhaust.

10 is a cross-sectional view of a forged blank for a fan housing for improved thermal stability in an embodiment of the present disclosure.

11 is a cross-sectional view of a machined fan casing having a ring of heat-resistant material that has been hot-seated to fit the fan casing of FIG. 10 in an embodiment of the present invention.

12 is a schematic cross-sectional view of a fan housing having an inner protective ring in an embodiment of the present invention.

FIG. 13 is a schematic cross-sectional view of a fan case having an outer protective ring in an embodiment of the present invention.

Fig. 14 is a cross-sectional view of a machined fan casing in an alternative embodiment having two stiffening rings and a guard ring that were installed in a hot fit with an interference fit on the fan casing, and the fan casing is located between them.

Fig. 15 is a schematic cross-sectional view of the fan casing of Fig. 14 having an inner protective ring opposite the outer stiffening rings.

Fig. 16 is a schematic drawing illustrating a shock holding region of a fan body blade in an embodiment of the present invention.

FIG. 17 is a schematic cross-sectional view of a fan blade of a fan case of FIG. 16.

Detailed description

Turning now to the drawings, in which like reference numerals and names refer to structurally and / or functionally similar elements, note that FIG. 1 is a schematic drawing of the general construction of a conventional gas turbine jet engine with a fan casing conventional in the prior art. Let us now consider FIG. 1, in which a gas turbine jet engine 100 is shown with a fan 102 having a plurality of fan blades 104 located inside a fan case 106. The fan 104 rotates on the axis of rotation along the axial line 107 to provide air flow, and the axial pressure booster compressor 108 is a low pressure compressor that supplies fresh air to the rotor 110 of the high pressure compressor, the attached blades and stators of which force air to pass into the chamber 112 combustion, increasing the pressure and temperature of the supply air. The rotor 114 of the high pressure turbine and its corresponding blades and stators are located inside the housing 116 of the high pressure turbine. The rotor 118 of the low pressure turbine and its corresponding blades and stators are located inside the housing 120 of the low pressure turbine. The rotor 118 of the low-pressure turbine and its corresponding blades and stators receive energy from the high-speed high-pressure gas flowing from the combustion chamber 112 and transmit energy to the shaft 122 of the low-pressure turbine, which in turn drives the fan 102, providing most of the axial pressure for gas turbine jet engine 100.

Figure 2 depicts a cross section of a forged billet for a fan casing, conventional for the prior art. Turning now to FIG. 2, it is noted that the forged blank 200 of the fan housing after machining provides the fan housing 202, shown by a dashed line. In this example, the forged billet 200 of the fan housing is forged from a titanium cylinder in one piece. Due to the operating temperatures and load characteristics of the particular gas turbine jet engine for which the fan housing 202 is intended, it may be required that the fan housing 202 be made of titanium. The weight of the forged blank for this particular forged blank 200 of the fan casing is approximately 3347 pounds. After machining, the fan housing 202 has a flight weight of approximately 975.2 pounds. On gas turbine jet engines, the fan casing can also be made of aluminum, steel or made of composite materials. Composite materials typically include core material, hardening material, and a resin binder component. The core materials are typically wood, foam, and honeycomb. Reinforcing materials include fiberglass, carbon fiber and Kevlar® (Kevlar). The resin component typically includes polyesters, vinyl esters, and epoxides. As technology evolves and temperatures rise in gas turbine jet engines, aluminum enclosures are often coated with Kevlar® to provide added strength to protect the fan enclosure. For even higher operating temperatures, for which aluminum or steel is not suitable, titanium is used, which can also be coated with Kevlar® if necessary for extra strength.

Structural details of the machined fan case 202 include a first stiffening ring 204 and a second stiffening ring 206. These two rings of stiffness help prevent the body 202 from acquiring an oval-shaped fan under the influence of the load and the temperature conditions to which it is exposed during engine operation. Auxiliary flange 208 will have openings passing through it and various engine components suspended from it, such as gearboxes, pipes, electrical wiring, and the like. A first guard ring 210 surrounds the outside of the fan housing 202 and provides additional strength to the fan housing. A second guard ring 212 surrounds the inside of the fan housing 202 and also provides additional strength to the fan housing. The section of the fan housing 202 between the first guard ring 210 and the second guard ring 212 is a blow holding region of a fan blade, where a fan blade, such as fan blade 104 (FIG. 1), may strike if it comes off the sleeve. Due to the size of the fan blades 104, which are usually the largest fan blades in a gas turbine jet engine, this section of the fan casing 202 is often designed to be exceptionally robust. Thus, the first and second guard rings 210, 212 provide additional strength.

Figure 3 depicts a cross section of a forged blank for a fan housing in an embodiment of the present invention. Turning now to FIG. 3, we note that it is possible to replace the fan housing according to the present description for the fan housing 202 for use in the same gas turbine jet engine for which the fan housing 202 was designed, either in a retrofit of an existing engine or in a newly manufactured engine . The features of the present invention are applicable to a fan housing of a gas turbine jet engine used in a variety of applications in which the fan provides air flow and creates axial pressure. Such applications include aviation, amphibious and other applications. The forged billet 300 of the fan casing after machining provides the fan casing 302, shown by a dashed line. In this example, the forged blank 300 of the fan housing is also forged from the titanium cylinder in one piece. In this example, the forged blank 300 has a simpler shape that simplifies the forging process, but it should be understood that the shape can be changed depending on the particular application. The weight of the forged billet for the forged billet 300 of the fan casing, in this embodiment, is approximately 2595 pounds, which is 752 pounds lighter than the forged billet 200 of the fan casing. After machining, the fan case 302 has a flight weight of about 751.3 pounds, which is 223.9 pounds lighter than the fan case 202. It should be understood that the materials, weight and characteristics of the forged workpiece 300 can be changed depending on the specific application.

Structural details of the machined fan case 302 include a first recess 304 for a stiffener ring and a second recess 306 for a stiffener ring located in the middle of the fan case 302. Two stiffening rings from two additional forged blanks (see FIGS. 5A, 5B, 6A and 6B) are respectively located in the first recess 304 for the stiffening ring and the second recess 306 for the stiffening ring (see FIG. 4), to prevent the housing 302 from acquiring oval-shaped fan under the influence of load and temperature conditions, which it is exposed to during engine operation. Depending on the design of the particular fan casing, more or less recesses can be provided for the stiffening rings, and they can be located in different positions on the surface of the fan casing. Although the stiffening rings 502, 602 are depicted as being placed on the outer surface of the fan casing 302, it should be understood that one or more stiffening rings can be mounted on the inner surface of the fan casing, depending on the particular application. The auxiliary flange 308 directed to the rear of the fan housing 302 may have holes passing through it or other mounting surfaces formed thereon and to support various engine components, such as gearboxes, pipes, electrical wiring, and the like, with it.

A recess for the protective ring 310 surrounds the inside of the fan housing 302 in a circle at the front end. In the recess 310 for the protective ring will be placed a protective ring of additional forged billets (see figa and 7B). 12 is a schematic cross-sectional drawing of a fan housing 302 equipped with a guard ring 702 housed in an inner recess 310 for the guard ring. The section of the fan casing 302, covering the recess 310 for the protective ring, represents the area where the fan blade, such as the fan blade 104 (figure 1), is likely to hit if it comes off its sleeve. This section of the fan housing 302 in this embodiment is relatively strong, and the protective ring of the additional forged billet, machined to a predetermined shape to fit with the notch 310 for the protective ring, provides additional strength and protective function. The fan casing 302 has no structure comparable to the first protective ring 210 that can be removed from the fan casing 302 of the present description due to the additional strength provided by the protective ring 702. It will be appreciated that in other embodiments a second or additional protective rings may be added. rings, depending on the specific application.

Fig. 5A shows a cross section of the forged blank for the first stiffening ring for the fan casing of Fig. 3 in the embodiment of the present description, and Fig. 5B depicts the first stiffening ring of Fig. 5A at the hot seat with an interference fit on the fan casing of Fig. 3 in an embodiment of the present invention. Turning now to FIGS. 5A and 5B, it is noted that the forged blank 500 of the first stiffening ring, after being machined to a predetermined shape to fit the first recess 304 for the stiffening ring, provides the first stiffening ring 502, shown by a dashed line in FIG. .5A. In this example, the forged blank 500 of the first stiffening ring is forged from an aluminum ring in one piece. The weight of the forged blank for the forged blank 500 of the first stiffener ring is approximately 154 pounds. After machining, the first stiffening ring 502 has a flight weight of approximately 41 lbs.

In this example, the first stiffening ring 502, manufactured separately from the fan housing 302, is installed by hot interference fit into the first recess 304 for the stiffening ring. At ambient temperature, the inner diameter of the first stiffening ring 502 will be slightly smaller than the outer diameter of the first stiffening ring recess 304. The first stiffening ring 502 is heated, which causes the first stiffening ring 502 to expand, increasing the inner diameter to a diameter that exceeds the outer diameter of the first stiffening ring recess 304, and creating a first ring gap 504 allowing the first stiffening ring 502 to be positioned as shown in the first recess 304 for the stiffening ring. In this position, the first stiffening ring 502 is allowed to cool, as a result of which it is reduced in diameter and is itself placed around the circumference in the first stiffening ring recess 304. At ambient temperature, due to the fact that the first stiffening ring 502 tends to return to its smaller inner diameter, but this is prevented due to the larger outer diameter of the first stiffening ring recess 304, a tight fit is formed with a radially compressive peripheral force applied to the fan housing 302 by the first stiffening ring 502, and a tensile peripheral force applied to the first stiffening ring 502 by the fan housing 302. In one embodiment, the radially compressive forces can be centered on the axis of rotation defined by the axial line 107. Also, radially compressive forces are continuously applied around the entire circumference of the first stiffening ring 502 without interruption.

Fig. 6A shows a cross section of a forged blank for a second stiffening ring for the fan casing of Fig. 3 in an embodiment of the present invention, and Fig. 6B depicts a second stiffening ring of Fig. 6A at a hot seat with an interference fit on the fan casing of Fig. 3 in an embodiment the implementation of the present invention. Turning now to FIGS. 6A and 6B, it is noted that the forged blank 600 of the second stiffening ring, after machining to a predetermined shape to fit with the second recess 306 for the stiffening ring, provides a second stiffening ring 602, shown by a dashed line in FIG. .6A. In this example, the forged blank 600 of the second stiffening ring is forged from an aluminum ring in one piece. The weight of the forged blank for the forged blank 600 of the second stiffening ring is approximately 148 pounds. After machining, the second stiffening ring 602 has a flight weight of approximately 40.6 pounds.

In this example, a second stiffening ring 602, manufactured separately from the fan housing 302, is hot-seated in an interference fit in the second recess 306 for the stiffening ring. At ambient temperature, the inner diameter of the second stiffening ring 602 will be slightly smaller than the outer diameter of the second recess 306 for the stiffening ring. The second stiffening ring 602 is heated, which causes the second stiffening ring 602 to expand, increasing the inner diameter to a diameter that exceeds the outer diameter of the second stiffening ring recess 306, and creating a second ring gap 604 allowing the second stiffening ring 602 to be positioned as shown in a second recess 306 for the stiffening ring. In this position, the second stiffening ring 602 is allowed to cool, as a result of which it is reduced in diameter and is itself placed around the circumference in the second stiffening ring recess 306. At ambient temperature, due to the fact that the second stiffening ring 502 tends to return to its smaller inner diameter, but this is prevented due to the larger outer diameter of the second stiffening ring recess 306, this leads to the formation of a tight fit with a radially compressing peripheral the force applied to the fan casing 302 by the second stiffening ring 602, and the tensile peripheral force applied to the second stiffening ring 602 of the fan casing 302. In one embodiment, the radially compressive forces can be centered on the axis of rotation defined by the axial line 107. Also, radially compressive forces are applied continuously around the entire circumference of the second stiffening ring 602 without interruption. Also, each stiffening ring, in one embodiment, is made in the form of a solid, unitary or solid continuous or seamless element, forged or manufactured by machine processing in the form of a closed loop. In another embodiment, the stiffener element ring may be made using an open loop element by joining the ends together, for example by welding, to form a closed loop shape.

It should be understood that stiffening rings may be located at other positions in the fan housing, depending on the application. Additionally, it should be understood that dimensions, length, shapes, materials and gaps may vary depending on the particular application. It should be understood that due to various factors, such as imperfect roundness, a stiffening ring, such as the first stiffening ring 502, cannot come into contact with 100% of the circumference of the outer surface of the fan casing 302. For example, the first stiffening ring 502 may come into contact with 70% of the circumference of the outer surface of the fan housing 302, but the amount of contact may vary, depending on the particular application. However, it is contemplated that the first stiffening ring 502 exerts radially compressive forces along the circumference of the inner peripheral surface of the first stiffening ring 502 when the first stiffening ring 502 is installed in a hot fit with an interference fit on the fan housing 302. Additionally, it should be understood that in some applications it may be appropriate to provide liner material between the stiffening ring which is hot-seated with an interference fit on the fan housing, such that compressive forces between the stiffener ring and the fan housing are transmitted through this liner material. In one embodiment, the liner material may be made of compressible material. It should be understood that in other embodiments, the liner material may be relatively rigid or may have other properties.

FIG. 7A is a cross-sectional view of a forged blank for a protective ring for the fan shell of FIG. 3 in an embodiment of the present disclosure, and FIG. 7B is a protective ring of FIG. 7A at a hot fit interference fit of the fan shell of FIG. 3 in an embodiment of the present descriptions. Turning now to FIGS. 7A and 7B, it is noted that the forged blank of the protective ring 700, after being machined to a predetermined shape for alignment with the recess 310 for the protective ring, provides the protective ring 702 shown by the outline drawn by the dotted line in FIG. 7A. In this example, the forged blank of the protective ring 700 is forged from a nickel-based superalloy ring, such as Inconel 718 (Inconel), in one piece. The weight of the forged blank for the forged blank 700 of the guard ring is approximately 467 pounds. After machining to a predetermined shape, the guard ring 702 has a flight weight of approximately 138.1 pounds. It should be understood that the guard ring may be located in other positions of the fan housing, depending on the application. Additionally, it should be understood that dimensions, lengths, shapes, materials and gaps may vary, depending on the particular application. For example, the guard ring 702 may be made of other heat resistant alloys, steel, titanium, or other appropriate materials to hold the blade. Also, the protective ring, in one embodiment, is made in the form of a solid, unitary or solid continuous or seamless element, forged or obtained by machine processing in the form of a closed loop. In another embodiment, the protective ring may be made using an open-loop-shaped member by joining the ends together, for example by welding, to form a closed-loop shape.

In this example, a guard ring 702, manufactured separately from the fan housing 302, is fitted with an interference fit into a notch 310 for the guard ring. At ambient temperature, the outer diameter of the protective ring 702 will be slightly larger than the inner diameter of the recess 310 for the protective ring. The fan casing 302 is heated, causing the fan casing 302 to expand, increasing the inner diameter to a diameter that is larger than the outer diameter of the protective ring 702, and leads to a gap 704 of the protective ring, making it possible to place the protective ring 702, as shown, in the recess 310 for protective ring. In this position, the fan casing 302 is allowed to cool, as a result of which it is reduced in diameter and allows the protective ring 702 to be placed circumferentially in the recess 310 for the protective ring. At ambient temperature, due to the fact that the fan casing 302 tends to return to its smaller inner diameter, but this is prevented by the larger outer diameter of the protective ring 702, which is reduced, this results in an interference fit with a radially compressive peripheral force applied to the guard ring 702 by the fan housing 302 and tensile peripheral force applied to the fan housing 302 by the guard ring 702. In one embodiment, the radially compressive forces could ut be centered on the axis of rotation defined by the center line 107, as schematically represented by arrows in FIG. 12. In one embodiment, radially compressive forces are continuously applied around the full circumference of the recess 310 for the protection ring of the fan housing 202 without interruption. It should be understood that due to various factors, such as imperfect roundness, a protective ring, such as a protective ring 702, cannot come into contact with 100% of the circumference of the inner surface of the fan case 302. For example, the guard ring 702 may come into contact with 70% of the circumference of the inner surface of the fan housing 302, but the amount of contact may vary, depending on the particular application. However, it is contemplated that the fan case 302 exerts radially compressive forces along the circumference of the inner peripheral surface of the protective ring recess 310 when the fan case 302 is installed in a hot fit with an interference fit on the protective ring 702. Additionally, it should be understood that in some applications it may be appropriate to provide liner material between the hot-fitting interference fit ring on the fan housing such that compressive forces between the protective ring and the vent housing insulator transmitted through the liner material. In one embodiment, the liner material may be made of compressible material. It should be understood that the liner material in other embodiments may be relatively rigid or may have other properties.

In the case of a fan casing made of composite material, the protective ring 702 can be cooled with liquid nitrogen to reduce its outer diameter, leading to the formation of a protective ring gap 704, allowing the protective ring 702 to be positioned, as shown, in the recess 310 for the protective rings. In this position, the protective ring 702 is allowed to warm to ambient temperature, increasing in diameter, and placed around the circumference in the recess 310 for the protective ring. At ambient temperature, due to the fact that the protective ring 702 tends to return to its larger outer diameter, but this is prevented by the smaller inner diameter of the recess 310 for the protective ring, this results in an interference fit with a radially compressive peripheral force, applied to the protective ring 702 by the fan housing 302, and tensile peripheral force applied to the fan housing 302 by the protective ring 702. One skilled in the art will appreciate that in some situations, in order to make a hot landing, it is also possible to use a combination of heating the fan casing 302 along with cooling the guard ring 702.

In one embodiment, the notch 310 for the protective ring is machined in a circumferential circumferential manner so that the inner diameter of the fan housing 302 at point A is smaller than the internal diameter of the fan housing 302 at point B. The taper can vary from one fan housing to another fan case, varying from a value that is only slightly more than 0 ° for a cylindrical case to an appropriate value that may depend on the specific geometry of the conical body mustache fan. The guard ring 702 is machined circumferentially on its outer surface to align with the same inverse taper. Even though the guard ring 702 is hot-pressed against the fan housing 302, the taper can add additional strength and prevent axial sliding of the guard ring 702 on the fan housing 302.

In addition, the machining for the fan housing 302 can be performed in a first direction, such as a radial direction, and the machining for the guard ring 702 can be performed in a second direction, such as an axis direction that is more or less perpendicular to the first direction. Since machining leaves a spiral, or contiguous, continuous groove on machined surfaces, the grooves on each surface can be aligned by cross-hatching with respect to each other, increasing the friction forces between the two surfaces and reducing the potential for rotation of the protective ring 702 inside the recess 310 for the protective rings. A plurality of recesses on a protective ring 702, which may be made, for example, of nickel-based superalloy, may be harder than a plurality of recesses in a recess 310 for a protective ring of a fan housing 302, which may be made of titanium, or in other fan cases, possibly made of steel or aluminum. Nickel-based superalloys can be pressed into softer recesses in titanium, steel or aluminum. Alternatively, the guard ring 702 can be spot welded at one or more locations in the guard ring recess 310, or bolted to one or more flanges attached to the guard ring recess 310 to prevent rotation of the guard ring 702 relative to the recess 310 for a protective ring. Machining in cross directions (cross-hatching) can also be applied or omitted, as appropriate, depending on the application.

FIG. 4 is a cross-sectional view of a machined fan case having two stiffening rings (FIGS. 5A, 5B, 6A and 6B) and a guard ring (FIGS. 7A and 7B) that have been hot-pressed to the fan case of FIG. .3, in an embodiment of the present invention. Turning now to FIG. 4, it is noted that the guard ring 702 may repeat a portion of the structure similar to the second guard ring 212, and may completely or partially avoid the use of the first guard ring 210, depending on the application. By hot seating an interference fit of the guard ring 702 on the inner diameter of the fan housing 302, as opposed to the outside, the harder heat-resistant alloy of the guard ring 702 can provide a surface that the blade should initially tear upon tearing. The softer titanium, steel, or aluminum of the fan housing 302 on the outside of the guard ring 702 can act as a shock absorber due to varying degrees of expansion between the two materials. When the superalloy of the guard ring 702 begins to move, it can press on titanium, steel, or aluminum of the fan housing 302 with a different expansion coefficient. This is similar to having two networks close together. The superalloy of the guard ring 702 can take an initial impact, and part of the force can be transmitted to the titanium, steel, or aluminum fan case 302 like a shock absorber.

The first stiffening ring 502 and the second stiffening ring 602 are shown arranged in the first stiffening ring recess 304 and the second stiffening ring recess 306, respectively. The first stiffening ring 502 and the second stiffening ring 602 provide stiffening to prevent eccentric deformation of the fan casing 302, or the formation of an oval shape, during engine operation under load and temperature conditions.

In this specific example, Table 1 below shows a comparison of forged workpiece weights and flight weights, and cost, of the fan casing 202 of the prior art compared to the fan casing 302 of the present invention.

Table 1 Part / Material Forged Workpiece Weight (lbs) Flight weight (lbs) Cost / pound total cost Fan housing 202
Titanium 3347,0 975.2 $ 8.00 $ 26,776.00 Fan housing 302
Titanium 2595,0 751.3 $ 8.00 $ 20,760.00 First stiffening ring 502 Aluminum 154.0 40.5 $ 1.50 $ 231.00 Second ring 602 stiffness Aluminum 148.0 40, 6 $ 1.50 $ 222.00 Protective Ring 702
Inconel 718 467.0 138.1 $ 7.00 $ 3,269.00 Amount 3364.0 970.5 $ 7.28 $ 24,482.00 Saving -17.0 4.7 $ 0.72 $ 2294.00

Thus, in this example, although the weight of the forged workpiece is 17 pounds more, the flight weight is 4.7 pounds less. In addition, the average cost per pound of materials for a fan case 302 is $ 0.72 per pound less than that for a fan case 202, resulting in total savings of $ 2,294.00. Also, in this example, it is believed that the fan case 302 is significantly more durable than the fan case 202.

In other applications, the savings may be more substantial. For example, for a fan casing that requires hardening from Kevlar®, the fan casing of the present invention may be strong enough to eliminate the need for hardening from Kevlar®, which can provide significant savings in both material and labor costs. The present invention can also be used with Kevlar® hardening in order to achieve higher holding strength of the fan casing. For gas turbine jet engines that currently use steel or titanium for fan housings, the present invention can allow steel or titanium to be replaced with aluminum, and the strength necessary for holding it can be provided by a nickel-based superalloy shielding ring or other suitable material. Since the same volume of aluminum or titanium is approximately 30% -55% by weight of the same volume of steel, substantial weight savings can be obtained as a result. This weight saving can translate into increased trucking capacity or reduced fuel consumption, or a combination of both.

In the production of gas turbine jet engines, the general direction is the manufacture of longer fan blades to increase axial pressure. The tips of the fan blades can rotate at supersonic speeds, while the base of the fan blades rotates at subsonic speeds. This can cause harmonic vibrations in the blades, leading to breaking off the tips of the blades. To counter this problem, instead of making direct fan blades, the blades are shaped more like wide oars. These wider and longer blades result in a larger mass that must be contained within the fan casing. Also, as engines become more efficient, they tend to operate at higher temperatures, potentially adding more difficulty to the retention problem. It is contemplated that the present invention can greatly help meet these requirements for greater holding strength of the fan housing and potentially lower overall weight and lower cost, as well as providing other features in addition to or instead of them, depending on the particular application.

Fig. 8 is a schematic drawing of air flow through a conventional gas turbine jet engine. Turning now to FIG. 8, we note that for a gas turbine jet engine incapable of reverse exhaust, air stream 824 flows into the fan housing 806 and into the booster compressor 808. The rotor 810 of the high pressure compressor compresses the air stream 824 when it enters the chamber 812 combustion. After passing through the high pressure and low pressure turbines, the air stream 824 flows out from the rear of the gas turbine jet engine 800. The heated air stream 824 in the combustion chamber 812 passes through it and exits the back of the gas turbine jet engine 800.

FIG. 9 is a schematic drawing of air flow through a conventional gas turbine jet engine capable of reverse exhaust. Turning now to FIG. 9, we note that in contrast to FIG. 8, a gas turbine jet engine 900 is capable of reverse exhaust, which causes a portion of the air stream 924, heated air 926, represented by dashed lines, to flow backward through the gas turbine jet engine 900 and into the region of the fan 902. The heated air 926 increases the temperature inside the fan case 906, which also increases the temperature of the fan case 906 directly in the area indicated by the general area 928. The temperature is Of course, one of the main factors in determining the fan housing 906 should be made of any material. When the temperature of the fan casing rises to more than 800 degrees, aluminum is not suitable. More expensive materials suitable for this temperature may be suitable, such as steel, titanium or superalloys.

10 is a cross-sectional view of a forged blank for a fan housing for improved thermal stability in an embodiment of the present disclosure. Turning now to FIG. 10, it should be noted that for gas turbine jet engines capable of reverse exhaust, it is assumed that the fan housing according to the present description can be used to counter thermal problems and improve the thermal resistance of the fan housing 1002. The forged blank 1000 of the fan housing is similar to the forged blank 300 of the fan housing shown in FIG. The forged billet 1000 of the fan casing after machining provides the fan casing 1002 shown by a dashed line that is similar to the fan casing 302. In this example, the forged blank 1000 of the fan housing is forged from aluminum in one piece.

The structural parts of the machined fan case 1002 are similar to the parts shown in FIGS. 3 and 4, but also include a heat-resistant ring recess 1012 that surrounds the inside of the fan case 1002 at a periphery at a location defined by a common area 928 in FIG. 9. A ring of heat-resistant material will be placed in a recess 1012 for a heat-resistant ring, in this example using a tight fit. The section of the fan housing 1002, which encompasses the recess 1012 for the heat-resistant ring, is an area where heated air from the return exhaust may increase the temperature of the fan housing.

It should be understood that the heat-resistant ring may be located in other positions of the fan housing, depending on the application. Additionally, it should be understood that dimensions, lengths, shapes, materials, and gaps may vary, depending on the particular application.

As described above, the machining for the fan housing 1002 can be performed in the first direction, for example in the radial direction, and the machining for the heat-resistant ring 1112 can be performed in the second direction, for example in the axial direction, which is more or less perpendicular to the first direction. Because machining can leave a spiral or contiguous groove written on the machined surfaces, the grooves on each surface can be aligned by cross-hatching relative to each other, increasing the friction forces between the two surfaces and reducing the potential for rotation of the heat-resistant ring 1112 inside the recess 1012 for heat resistant ring. Many of the recesses on the heat-resistant ring 1112, which is made of titanium, can be more rigid than many recesses on the recess 1012 for the heat-resistant ring in the fan housing 1002, which is made of aluminum. Titanium recesses can be pressed into softer aluminum recesses. Alternatively, the heat-resistant ring 1112 may be spot welded in one or more places to the heat-resistant ring recess 1012 or bolted to one or more flanges attached to the heat-resistant ring recess 1012 to keep the heat-resistant ring 1112 from rotating relatively recesses 1012 for a heat-resistant ring. Machining in cross directions in this case may not be required or may be applied in addition to this.

11 is a cross-sectional view of a machined fan case having a ring of heat-resistant material that has been hot-seated to fit the fan case of FIG. 10 in an embodiment of the present invention. Turning now to FIG. 11, it is noted that a heat-resistant ring 1112 is shown mounted on a hot fit with an interference fit on the inner diameter of the fan housing 1002 in a recess 1012 for the heat-resistant ring. In this example, the heat-resistant ring 1112 is made of titanium, but can also be made of other materials that have a combination of heat resistance and strength properties to maintain the structural integrity required for the fan housing 1002, such as steel, alloy steel, or any quantity commonly used aerospace superalloys. The heat-resistant ring 1112 can be made of titanium sheet material, which is cut, bent into a cylindrical shape, welded along the seam and formed to fit with the inner diameter of the recess 1012 for the heat-resistant ring. The heat resistant ring 1112 can also be forged as described above.

An interference fit can be performed as described above by heating the fan housing 1002, causing it to expand in diameter and allowing the heat-resistant ring 1112 to slide into a place where, after cooling, the fan housing 1002 and heat-resistant ring 1112 apply force to each other, forming a hot fit with an interference fit. Alternatively, the heat-resistant ring 1112 can be cooled with liquid nitrogen, reducing its outer diameter and allowing the heat-resistant ring 1112 to slide into the recess 1012 for the heat-resistant ring. Also, a combination of heating the fan housing 1002 and cooling the heat-resistant ring 1112 can be used to ensure a tight fit. The titanium of the heat-resistant ring 1112 is not structurally weakened due to the temperatures of the fan casing and serves as a buffer for the aluminum fan casing 1002 due to different degrees of expansion between the two materials. The titanium of the heat-resistant ring 1112 is exposed to internal temperatures in the fan housing, and some of the heat is transferred to the aluminum fan housing 1002. Titanium provides the necessary strength, which is absent in aluminum at higher temperatures. The protective ring 1102 may be made of superalloy. It should be understood that due to various factors, such as imperfect roundness, a heat-resistant ring, such as heat-resistant ring 1112, cannot come into contact with 100% of the circumference of the outer surface of the fan casing 1002. For example, the heat-resistant ring 1112 may come into contact with 70% of the circumference of the inner surface of the fan housing 1002, but the amount of contact may vary, depending on the particular application. However, it is contemplated that the fan case 1002 exerts radially compressive forces along the circumference of the inner peripheral surface of the heat-resistant ring recess 1012 when the fan case 1002 is installed in a hot fit with an interference fit on the heat-resistant ring 1112. Additionally, it should be understood that in some applications it may it should be appropriate to provide liner material between the heat-resistant ring mounted on a hot seat with an interference fit on the fan case, so that compressive forces between the thermos The ring and fan casing were transmitted through the liner material. In one embodiment, the liner material may be made of compressible material. It should be understood that the liner material in other embodiments may be relatively rigid or may have other properties, such as improved thermal insulation properties, to further protect the fan casing.

The first recess 1104 for the stiffening ring and the second recess 1106 for the stiffening ring can be made, for example, in aluminum, titanium or steel. Depending on the particular gas turbine jet engine in question, a shielding ring and one or more stiffening rings may not necessarily be used with a heat-resistant ring, and a heat-resistant ring may not necessarily be used with a shielding ring and with one or more stiffening rings. The present description provides the engine designer with many options regarding materials, weights, strengths and thermal resistance, which can be combined to create the optimal design for the goals and requirements of a particular engine. For example, the fan housing 302 may be made of a relatively lightweight but relatively inexpensive material, such as aluminum, and the guard ring 702 may be made of a material having a relatively higher strength (such as Inco 718 superalloy) compared to the material of the fan housing. However, since the protective ring 702 can be made substantially smaller in mass than the mass of the fan casing 302, the material of the protective ring 702 can be more expensive or heavier than the material of the fan casing 302, and yet it is possible to achieve savings in total weight or expense, or both, and in another, depending on the specific application. Similarly, the fan casing 1002 may be made of a material with relatively low thermal resistance, such as aluminum, and the heat-resistant ring 1102 may be made of a material having a relatively higher thermal resistance (for example, such as titanium) compared to the case material fan. However, since the heat-resistant ring 1112 can be made substantially smaller in mass than the mass of the fan casing 1002, the material of the heat-resistant ring can be more expensive or heavier than the material of the fan casing 1002, and yet it is possible to achieve savings in full weight or costs, or both, depending on the specific application.

As mentioned, FIG. 12 schematically illustrates a protective ring 702 housed in a recess 310 for a protective ring formed on the inner surface of the fan housing 302. With reference to FIG. 13, it should be understood that the protective ring 702a may be placed in the recess 310 for the protective ring formed on the outer surface of the fan housing 302, as shown in FIG. 13. In this example, the guard ring 702a exerts radially compressive forces directed towards the axis of rotation defined by the center line 107, as schematically represented by arrows in FIG. 13. In one embodiment, radially compressive forces are continuously applied around the full circumference of the guard ring 702a without interruption.

As mentioned, stiffening rings can be placed at a variety of locations along the fan housing 302. Fig. 14 shows an example in which a pair of stiffening rings 502, 602 are placed opposite the guard ring 702b. As shown in cross-section in FIG. 15, each of the stiffener element ring 502 and the guard ring 702b are hot-pressed to fit the fan body 302, the fan body 302 being located between the stiffener ring 502 and the guard ring 702b. The stiffening ring 602 was likewise installed on a hot fit with an interference fit on the fan housing 302, where the fan housing 302 is located between the stiffening ring 602 and the guard ring 702b. The stiffening rings 502, 602, in addition to their stiffening functions, in this embodiment can provide additional strength to complement the strength provided by the guard ring 702b.

Again, the fan housing 302 can be made of a relatively lightweight but relatively inexpensive material, such as aluminum, and the stiffening rings 502, 602 can be made of a material having a relatively higher holding or stiffening force (such as an Inco 718 superalloy or other superalloy , steel, titanium, or other appropriate materials) compared to the fan casing material. However, since the stiffening rings 502, 602 can be made substantially less mass than the mass of the fan casing 302, the material of the stiffening rings 502, 602 can be more expensive or heavier than the material of the fan casing 302, and yet it is possible to achieve savings in total weight or consumption, or both, depending on the specific application.

As schematically shown in FIG. 16, a section of the fan casing 302 spanning the width of the guard ring 702 is an impact region of a fan blade 1600, where a fan blade, such as a fan blade 104 (FIGS. 1, 16), or a portion of a fan blade can strike if the blade, or part of it, is torn off of its sleeve 102 or the remaining part of the blade. In this embodiment, the fan blade impact region 1600 extends from the engaging portion 1601 at the front end of the guard ring 702 to the tail end 1603 of the guard ring 702. Region 1600 can be determined by appropriate computer simulation and / or empirically through laboratory studies of the probable or potential trajectory of the detachable blade fan or fan blade section. It should be understood that in some embodiments, the width of the protective ring may exceed the width of the potential impact region.

Inside the fan blade impact region 1600, there is a region 1602 in which the fan blade or portion of the blade, likely or potentially, may first hit the fan housing 302. As shown in FIG. 16, it is assumed that for many engine designs, the width of the initial impact region 1602 extends from the line in front of the leading edge 1604 of the fan blade 104 to the line behind the trailing edge 1608 of the fan blade 104. The forward direction is the direction toward the front of the fan housing 302 in which air is received. The tail direction is the direction in which air is discharged from the engine to provide axial pressure in the forward direction.

As best seen in cross-sectional view of the fan blade 104 in FIG. 17, the leading edge 1604 is a portion of the fan blade 104 that extends further in the forward direction. Conversely, the trailing edge 1608 of the fan blade 104 is a portion of the fan blade 204 that extends in the tail direction. In the illustrated embodiment, the width of the guard ring 702 overlaps at least the width of the fan blade initial impact region 1602. Therefore, the width of the guard ring 702, when installed in the engine, extends from at least a line in front of the leading edge 1604 of the fan blade 104 to a line behind the trailing edge 1608 of the fan blade 104. It should be understood that the fan blade impact holding region 1600 and the width of the guard ring 702 can extend in one or both of the front and tail directions beyond the boundaries of the initial impact region 1602, as shown in FIG. 16.

In the illustrated embodiment, the guard ring 702 has a thickness T (FIG. 16). The thickness T of the guard ring 702 in the illustrated embodiment is sufficient to prevent penetration of the guard ring 7.02 by a separated blade 104 or a fragment of the blade. The thickness can be determined by appropriate computer simulations or empirical tests based on the projected or observed mass and speed of the blade or fragments of the blade and the strength of the material of the protective ring 702.

In the described embodiments, each of the rings, such as rings 702, 702a, 702b, 502, 602, 1112, is described as being placed in an associated recess. It should be understood that one or more rings manufactured separately from the fan housing 302 can be attached to the fan housing to reinforce the fan housing without using a recess.

In the described embodiments, each of the rings, such as rings 702, 702a, 702b, 502, 602, 1112, is described as being placed by interference fit on the fan housing 302, 302a. It should be understood that one or more rings manufactured separately from the fan case 302 can be attached to the fan case to reinforce the fan case so that radially compressive forces are applied between the corresponding ring and the fan case, without using a tight fit.

Thanks to the present invention, specialists in the art will understand many modifications in the design, and they themselves will be able to offer widely varying embodiments and applications of the invention, without going beyond the scope of the present invention.

Claims (58)

1. A method of hardening a fan casing in a gas turbine jet engine, comprising surrounding the outer peripheral surface of the protective ring, which is installed by tight fit in the area of holding the fan blades in the fan casing of the gas turbine jet engine having a turbine casing surrounding the turbine, adapted for rotation along the axis rotation inside said housing, and a fan having fan blades connected to said turbine and adapted to rotate along the axis of rotation inside the said fan casing, each fan blade having a leading edge and a trailing edge using the inner peripheral surface of the holding area of the fan blades in the fan casing of the gas turbine jet engine, and applying radially compressive forces to the said outer peripheral surface along the circumference of the said inner peripheral surface and across the width of the holding area of the fan blades, continuing at least at oyanie front of the front edge of each fan blade and at least at a distance behind the trailing edge of each fan blade, using said surrounding an inner peripheral surface. 2. The method according to claim 1, wherein said applying a radially compressive force includes placing said protective ring inside a recess defined by said fan case and having a shape preventing said protective ring from being displaced in the longitudinal direction relative to said fan case. 3. The method according to claim 1, wherein said radially compressive forces are directed toward a center located on said axis of rotation. 4. The method according to claim 1, further comprising machining to form a recess for the protective ring circumferentially in the inner surface toward the front end of the fan casing, wherein said surroundings and attachment include placing said protective ring in said recess for the protective ring by means of a tight fit. 5. The method according to claim 1, further comprising machining to form a recess for the protective ring circumferentially in the outer surface toward the front end of the fan casing, said surroundings and attaching include placing said protective ring in said recess for the protective ring by means of a tight fit. 6. The method according to claim 4, in which said machining further comprises machining said recess for the protective ring in said first surface of the fan housing in a first direction, wherein a plurality of recesses are formed and aligned on said inner surface in said first direction. 7. The method according to claim 6, further comprising, before said machining of the recess, forging said protective ring in one piece and machining said protective ring to a predetermined shape for alignment with said recess for the protective ring. 8. The method according to claim 7, in which said protective ring is forged from a material in the form of a single part, wherein said material is selected from the group consisting of steel, titanium, nickel-based superalloy. 9. The method according to claim 7, in which said machining of the protective ring further comprises machining the outer surface of said protective ring in a second direction, in which a plurality of recesses are formed and aligned on said outer surface in said second direction, wherein, when said inner the surface of said recess for the protective ring and said outer surface of said protective ring are placed together, said plurality of recesses on said inside the lower surface of said recess for a protective ring and said plurality of recesses on said outer surface of said protective ring are aligned by cross-hatching with respect to each other, increasing the friction forces between said recess for the protective ring and said protective ring and reducing the potential for rotation of said protective ring inside said recess for the protective ring. 10. The method according to claim 7, further comprising spot welding said protective ring with said recess for the protective ring at least at one location to prevent rotation of said protective ring relative to said recess for the protective ring. 11. The method according to claim 7, further comprising bolting said protective ring to at least one flange attached to said recess for the protective ring to prevent rotation of said protective ring relative to said recess for the protective ring. 12. The method according to claim 7, in which said machining of the protective ring further comprises machining said protective ring with a reverse taper, in which the first outer diameter of said protective ring at a first point toward the front end is smaller than the second inner diameter of said protective rings at a second point remote from said front end. 13. The method according to claim 4, wherein said machining further comprises machining said recess for the inverse taper protective ring, in which the first inner diameter of the fan casing at the first point of said recess for the protective ring toward said front end is less than the second inner diameter of the fan casing at the second point of said recess for the protective ring located at a distance from said front end. 14. The method according to claim 4, in which said placement further comprises heating the fan casing to cause the inner diameter of said recess for the protective ring to increase to a second diameter that is larger than the outer diameter of said protective ring at ambient temperature, the location of said protective ring in said recess for the protective ring and allowing the fan casing to cool to said ambient temperature, causing said recess for protection of the ring to tend to decrease from said second diameter to said inner diameter, but to prevent it from doing so by said outer diameter of said protective ring at said ambient temperature, providing said interference fit. 15. The method according to claim 4, in which said placement further comprises heating the fan casing to cause the inner diameter of said recess for the protective ring to increase to a second diameter, cooling said protective ring to cause the outer diameter of said protective ring to decrease to a second diameter, wherein said second diameter of said protective ring is smaller than said second diameter of said recess for said protective ring, the arrangement of said protective ring in said recess for the protective ring and allowing the fan body to cool to ambient temperature, causing said recess for the protective ring to decrease from said second diameter to said inner diameter and allowing said protective ring to heat to said ambient temperature, causing said protective ring to increase to said outer diameter, resulting in said interference fit. 16. The method according to claim 4, in which said placement further comprises cooling said protective ring to cause the outer diameter of said protective ring to decrease to a second diameter, wherein said second diameter of said protective ring is smaller than an inner diameter of said recess for the protective ring, the location of said protective ring in said recess for the protective ring and allowing the protective ring to heat to said ambient temperature, causing said protective ring to increase to said outer diameter, but to prevent this from happening by said inner diameter of said recess for the protective ring at said ambient temperature, providing said interference fit. 17. The method according to claim 4, further comprising machining to form at least one recess for the stiffening ring circumferentially in the surface of the fan casing and placing the stiffening ring in said at least one recess for the stiffening ring, wherein said stiffening ring resists acquisition oval-shaped fan casing under the action of the load and temperature conditions to which it is exposed during the operation of a gas turbine jet engine. 18. The method according to 17, in which said recess for the stiffening ring is performed by machining in the outer surface of the fan casing, and said arrangement of said stiffening element ring further comprises heating said stiffening ring to cause the first inner diameter of said stiffening ring to increase to a second inner a diameter that is larger than the outer diameter of the at least one recess of the stiffening ring at ambient temperature, the location mentioned about a stiffening ring in said at least one recess of the stiffening ring and allowing said stiffening ring to cool to said ambient temperature, causing said stiffening ring to decrease from said second inner diameter to said first inner diameter, but to prevent this from happening by said outer diameter of said at least one recess of the stiffening ring, providing the mentioned hot fit. 19. The method according to claim 1, wherein said fan casing is made of a first material having a first strength, and said protective ring is made of a second material having a second strength that is higher than the strength of the first material. 20. The method according to claim 19, wherein said first material is aluminum, and said second material is a nickel-based superalloy. 21. The method according to 17, in which said fan casing is made of a first material having a first strength, and said stiffening ring is made of a second material having a second strength that is higher than the strength of the first material. 22. The method of claim 21, wherein said first material is aluminum and said second material is a nickel-based superalloy. 23. The method according to claim 1, in which said protective ring has a thickness sufficient to prevent penetration of said protective ring with a separated blade. 24. A device for hardening a fan casing in a gas turbine jet engine for use in a gas turbine jet engine having a turbine casing that surrounds a turbine adapted to rotate along a rotation axis inside said casing and a fan having fan blades attached to said turbine and adapted for rotation along the axis of rotation inside the fan housing, wherein each fan blade has a leading edge and a trailing edge, the device comprising a fan casing having an inner peripheral surface that includes a holding area of the fan blades and a protective ring having an outer peripheral surface and tightly attached to said inner peripheral surface of the fan casing, said protective ring being located around the circumference of said fan casing in within said holding area of the fan casing to hold said fan blades in case mentioned the fan blades are separated from said fan, wherein said protective ring extends at least a distance in front of the leading edge of each fan blade and at least a distance behind the trailing edge of each fan blade, said holding area of the fan blades of said fan housing being adapted by said hot interference fit for applying radially compressive forces to said outer peripheral surface of said protective rings along the circumference of said holding region of the fan blades of said inner peripheral surface. 25. The device according to paragraph 24, in which the aforementioned protective ring has a thickness sufficient to prevent penetration of the said protective ring with a separate blade. 26. A device for hardening a fan casing in a gas turbine jet engine, intended for use in a gas turbine jet engine having a turbine casing that surrounds a turbine adapted to rotate along an axis of rotation inside the casing, and a fan having fan blades attached to said turbine and adapted for rotation along the axis of rotation inside the aforementioned fan casing, each fan blade having a leading edge and a trailing edge, the device comprising a fan case having a front end, which includes a holding area of the fan blades, and an inner surface and an outer surface towards said front end of the fan case, in which the inner surface defines a recess for the protective ring produced by machining around the circumference in the said inner surface the fan casing and within the aforementioned area of the holding of the fan blades, and a protective ring adapted for placement by means of hot interference fit in said recess for the protective ring and extending at least a distance in front of the leading edge of each fan blade and at least a distance behind the trailing edge of each fan blade to provide radially compressive forces applied from said fan housing and said protective ring . 27. The device according to p. 26, in which the said recess of the protective ring is performed by machining around the circumference in the said inner surface of the fan casing towards the front end of the fan casing. 28. The device according to p. 26, in which the aforementioned protective ring is forged from the retaining material in the form of one part and subjected to machining to a predetermined shape, while the said material is selected from the group consisting of steel, titanium, nickel-based superalloy. 29. The device according to item 27, in which the outer diameter of the said protective ring is slightly larger than the inner diameter of the said recess for the protective ring at ambient temperature, and the fan casing is heated to cause the said inner diameter of the said recess for the protective ring to increase to a second diameter which is larger than said outer diameter of said protective ring, allows said protective ring to be located in said recess of the protective ring, forming a tightened tight fit when the fan casing is cooled to the mentioned ambient temperature. 30. The device according to clause 29, in which the said recess for the protective ring is subjected to machining with reverse taper, such that the first inner diameter of the fan casing at the first point towards said front end is less than the second inner diameter of the fan casing at the second point located at a distance from said front end, said protective ring being machined circumferentially on its outer surface to match said reverse taper. 31. The device according to item 27, in which the outer diameter of said protective ring is slightly larger than the inner diameter of said recess for the protective ring at ambient temperature, and the fan casing is heated to cause said inner diameter of said recess for the protective ring to increase to a second diameter and said protective ring is cooled to cause the outer diameter of said protective ring to decrease to a second diameter in which said second diameter of said protective The smaller ring than said second diameter of said recess for the protective ring allows said protective ring to be located in said recess for the protective ring, providing said interference fit while the fan casing is cooled and said protective ring is heated to said ambient temperature. 32. The device according to item 27, in which the outer diameter of said protective ring is slightly larger than the inner diameter of said recess for the protective ring at ambient temperature, and said protective ring is cooled to cause the outer diameter of said protective ring to decrease to a second diameter, wherein said second diameter of said protective ring is smaller than the inner diameter of said recess for the protective ring, allow said protective ring to be located in said a removed recess for the protective ring, providing said interference fit when said protective ring is heated to said ambient temperature. 33. The apparatus of claim 27, further comprising a plurality of recesses aligned in a first direction on a machined inner surface of said recess for a protective ring, and a plurality of recesses aligned in a second direction on a machined outer surface of said protective ring, wherein when said inner surface of said recess for a protective ring and said outer surface of said protective ring are hot-seated together hom, said plurality of recesses on said inner surface of said recess for a protective ring and said plurality of recesses on said outer surface of said protective ring are aligned by cross-hatching with respect to each other, increasing the frictional forces between said recess for the protective ring and said protective ring and reducing the potential for rotation of said protective ring within said recess for the protective ring. 34. The device according to p. 26, further comprising welding by spot welding at least one location of the said protective ring to the said recess for the protective ring, to prevent rotation of the said protective ring relative to the said recess for the protective ring. 35. The device according to p. 26, further containing at least one flange attached to said recess for the protective ring, in which the said protective ring is bolted to the said at least one flange to prevent rotation of the said protective ring relative to the said recess for the protective ring . 36. The device according to p. 26, further comprising at least one recess for the stiffening ring, made by machining around the circumference in the surface of the fan casing, and a stiffening ring placed in said at least one recess for the stiffening ring, said stiffening ring on a tight fit with an interference fit, while the mentioned stiffness ring resists the oval shape of the fan casing under the influence of the load and the temperature conditions to which it is exposed during operation turbine jet engine. 37. The device according to clause 36, in which said stiffening ring is forged from aluminum in one piece. 38. The device according to clause 36, in which said recess for the stiffening ring is performed by machining in the outer surface of the fan casing, and the inner diameter of said stiffening ring is slightly smaller than the outer diameter of said at least one recess for the stiffening ring at ambient temperature, and said stiffening ring is heated to cause said inner diameter of said stiffening ring to increase to a second diameter that is larger than said outer diameter of said that at least one stiffening ring notch, enabling said stiffening ring disposed in said at least one stiffening ring notch, giving rise to said shrink interference fit when said stiffening ring cools to said ambient temperature. 39. The device according to p, in which the fan casing is forged from one material: steel, titanium and aluminum. 40. The device according to p, in which the fan casing is made of one material: steel, titanium and aluminum. 41. The device according to p, in which the fan casing is made of composite material. 42. The device according to paragraph 41, in which the outer diameter of said protective ring is slightly larger than the inner diameter of said recess for the protective ring at ambient temperature, and said protective ring is cooled to cause said outer diameter of said protective ring to decrease to a second diameter, which is smaller than said inner diameter of said recess for the protective ring, enable said protective ring to be located in said recess for the protective ring, providing an interference fit when said protective ring is heated to said ambient temperature. 43. The device according to p, in which said fan casing is made of a first material having a first strength, and said protective ring is made of a second material having a second strength that is higher than the strength of the first material. 44. The device according to item 43, in which said first material is aluminum, and said second material is a heat-resistant nickel-based alloy. 45. The device according to clause 36, wherein said fan casing is made of a first material having a first strength, and said stiffening ring is made of a second material having a second strength that is higher than the strength of the first material. 46. The device according to item 45, in which the aforementioned first material is aluminum, and said second material is a heat-resistant alloy based on Nickel. 47. A gas turbine jet engine comprising a fan housing having an inner peripheral surface that includes a holding area of fan blades, a turbine housing surrounding a turbine adapted to rotate along an axis of rotation within said housing, a fan having fan blades attached to said turbine and adapted for rotation along the axis of rotation inside said fan case, wherein each fan blade has a leading edge and a trailing edge, and a protective e ring having an outer peripheral surface, said protective ring being arranged around said fan in order to hold said fan blades in case said fan blades are separated from said fan, said protective ring extending at least a distance in front of the leading edge of each blade the fan and at least a distance behind the trailing edge of each fan blade, wherein said holding area of the fan blades at the fan casing by means of a hot fit with an interference fit on said protective ring is adapted to apply radially compressive forces to said outer peripheral surface of said protective ring, along the circumference of said holding region of the fan blades of said inner peripheral surface. 48. The engine according to clause 47, further comprising at least one flange attached to the fan casing, wherein said protective ring is bolted to said at least one flange to delay rotation of said protective ring relative to said fan casing. 49. The engine of claim 48, further comprising at least one recess for the stiffening ring, machined circumferentially in the surface of the fan casing, and a stiffening ring housed in said at least one recess for the stiffening ring, wherein said stiffening ring placed on a tight fit with an interference fit, while the mentioned stiffness ring resists the oval shape of the fan casing under the influence of the load and the temperature conditions to which it is exposed during operation zoturbine jet engine. 50. The engine according to clause 47, in which the fan casing has a middle section having an inner surface that defines a recess for the heat-resistant ring, machined circumferentially in said surface of the fan casing, the engine further comprising a heat-resistant ring adapted to be placed in said a recess for the heat-resistant ring to provide radially compressive forces applied from said fan casing to said heat-resistant ring. 51. The engine according to item 50, in which the aforementioned heat-resistant ring is adapted for placement on a hot landing with an interference fit. 52. A method of modernizing a gas turbine jet engine, comprising removing the fan casing from the jet engine and installing a replacement fan casing on said jet engine, wherein said replacement fan casing has a protective ring located in the inner peripheral surface of the replacement fan casing through a tight fit and adapted for holding the fan blades striking into said replacement fan case, while said protective ring extends at least over a distance in front of the front edge of each said fan blade and at least at a distance behind the trailing edge of each said fan blade when it is taken within the substitute fan case. 53. The method according to paragraph 52, further comprising placing said protective ring in a peripheral recess of said inner peripheral surface of the replacement fan housing in a tight fit, prior to installing said replacement fan housing. 54. A method of operating a gas turbine jet engine, comprising rotating the fan blades located inside the fan housing using a turbine along the rotation axis to provide air flow and axial pressure, and applying radially compressive forces to the outer peripheral surface of the protective ring using the inner peripheral surface the area of holding the fan blades of the fan casing surrounding and placed with a hot fit with an interference fit on said outer peripheral surface a protective ring, wherein said radially compressive forces are applied along the circumference of the inner peripheral surface and across the width of the holding area of the fan blades, extending at least a distance in front of the front edge of each fan blade and at least a distance behind the trailing edge of each fan blade, and are directed to the center located on the said axis of rotation. 55. The method according to item 54, further comprising applying radially compressive forces to the outer peripheral surface of the fan housing using the inner peripheral surface of the stiffening ring surrounding said outer peripheral surface of the fan housing. 56. The method according to item 54, further comprising applying radially compressive forces to the outer peripheral surface of the heat-resistant ring, using the inner peripheral surface of the fan housing surrounding said outer peripheral surface of the heat-resistant ring. 57. A device for hardening a fan casing in a gas turbine jet engine, intended for use in a gas turbine jet engine having a turbine casing that surrounds a turbine adapted to rotate along the axis of rotation inside the casing, and a fan having fan blades attached to said turbine and adapted for rotation along the axis of rotation inside the aforementioned fan casing, each fan blade having a leading edge and a trailing edge, the device comprising a fan casing having a front end and an inner surface and an outer surface towards said front end of the fan casing, wherein said inner surface defines a holding area of the fan blades and a heated reverse exhaust region in which said fan casing is made of a first material having a first holding strength and first thermal resistance, a protective ring having an outer peripheral surface, said protective ring being located within the said holding region of the fan casing for holding said fan blades in case said fan blades are separated from said fan, said protective ring extending at least a distance in front of the leading edge of each fan blade and at least a distance behind the trailing edge each fan blade, wherein said holding area of the fan blades of said fan housing is connected by hot landing with by pulling against said protective ring for applying radially compressive forces to said outer peripheral surface of said protective ring, said protective ring being made of a second material having a second strength that is higher than the strength of the first material, a stiffening ring adapted to be placed on said outer the surface of the fan casing behind said protective ring to provide radially compressive forces applied from said stiffening ring to a crumpled outer surface of the fan casing, and wherein said stiffening ring is made of a material having a strength that is higher than the strength of the first material, and a heat-resistant ring adapted to be placed on said inner surface of the fan casing within said heated area of the return exhaust to provide radially compressive forces applied from said heated region of the reverse exhaust of the fan casing to said heat-resistant ring, and in which yanutoe heat resistance ring is made of a third material having a second thermal resistance, which is higher than the thermal resistance of the first material. 58. The apparatus of claim 57, wherein said first material is aluminum, said second material is nickel-based superalloy, said stiffening ring material is nickel-based superalloy, and said third material is titanium.

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