Birotary srew-type blower

FIELD: engines and pumps.

SUBSTANCE: invention relates to aircraft engine production, particularly to aircraft gas turbine engine blowers. Proposed birotary blower consists of two consecutive impellers running in opposite directions. To produce required profiles of both impellers, necessary distributions of blades angles are corrected by algebraic summation of their designed angles. Birotary screw-type blower can be cowled.

EFFECT: reduced operating noise.

2 cl, 4 dwg

The invention relates to aircraft engine, particularly to a fan aircraft gas turbine engines.

One of the main tasks in the development of aircraft engines, the construction of which is applied birotational windowancestor composed of two oppositely rotating about the axis of the propfan wheels, is satisfactory acoustic characteristics such windowancestor while ensuring the required aerodynamic and structural characteristics. Created birotational windowancestor the noise that must be reduced to the required international standards, is a consequence of the aerodynamic interaction of the fields of the currents formed by rotating in opposite directions, the blades of the impeller, as well as interaction of trailing vortices from the blades of the first wheel and a second wheel blades and interaction trailing vortices from both blades of the wheels for the second impeller. Due to the last two circumstances peripheral portions of the blades make a more significant contribution in the generated windowancestor noise.

When designing the impeller blades propfan need to develop its geometry, which should provide at the output of blades required distribution VD is l, the height of the blade degrees of increase of the total pressure airflow rates and efficiencies occurring in the interscapular channels processes. Directly the shape of the blade is determined found when designing distributions along the height of the blades of the required angles of entry and exit angles to the median skeletal surface of zero thickness and, consequently, the distribution of bend angles of this skeletal surface, which is defined as the difference between the angles of entrance and exit angles. Then the skeletal surface wears the skin of the aerodynamic profiles with varying in height blade form.

The present invention is applied to both wheels at the stage of profiling blades before their skeletal surface of zero thickness, which is already found in the distribution of the required angles of entrance and exit angles and angles of bending, it is necessary cross-sections of the blades to "dress" the aerodynamic profiles of the selected form.

Known ntakarutimana birotational wincounter, German patent DE No. 3933776 on 10 October 1989, consisting of two oppositely rotating about the axis of the propfan impellers with blades made with an aerodynamic profile in the cross sections. The traditional form of both blades of the impeller allows us to conclude that these blades are made with aerodyna the practical load profiles, slightly varying along the height of the blades to ensure approximately uniform vertical distribution generated by impellers values of degrees of increase of the total pressure. As a consequence, the disturbance to the flow of the peripheral areas of blades is as significant as other areas of blades. So remain intense aerodynamic interaction between both blades of the impeller and the interaction of trailing vortices, which leads to elevated levels generated by windowancestor noise.

Known ntakarutimana birotational wincounter, U.S. patent No. 5,028,207 dated July 2, 1991, consisting of adjacent the first impeller and the second impeller with blades, in which the contours of cross-sections form the airfoils covering set for the profiling of skeletal surface of zero thickness, built on varying along the height of the blades of the corners of the entrance and exit angles and the angles of the bend profile. In this windowancestor peripheral profiles of both blades of the impeller are made with significant curves, indicating a significant aerodynamic load peripheral areas of the blades, resulting in a disturbing effect on the flow of the peripheral teaching Dow blades is quite significant. Because of this, and in this windowancestor remain intense aerodynamic interaction between both blades of the impeller and the interaction of trailing vortices, and therefore, the occurrence of high noise levels.

The technical objective of the proposed technical solution is to reduce the level of noise generated birotational windowancestor.

The claimed technical solution is significantly attenuated:

- the intensity of the aerodynamic interaction of the fields of the currents generated by the rotating blades of the impeller;

- the intensity of the interaction of trailing vortices from the blades of the first wheel and a second wheel blades;

- the intensity of the interaction of trailing vortices from both blades of the wheels for the second impeller,

which leads to the reduction of noise impellers birotational propfan.

Technical result is achieved by the claimed birotational windowancestor consisting of adjacent the first impeller and the second impeller with blades, in which the contours of cross-sections form the airfoils covering a given profiled skeletal surface of zero thickness, which is built on varying along the height of the blades of the set angles of the input (a_WH), is specified in the corners of output (In _wyhand educated of their difference to bend (a_i) profile, in both impellers to reduce the bending angle (a_i) profile in the peripheral areas of the blades and increase the bending angle (a_i) profile in the median areas of blades by changing the angle of the output at a constant angle of entrance (a_WH), the aerodynamic profile in the cross sections of the blades above the cross-section, spaced from the sleeve 0.25-0.35 height (h_b) blades perform with modified corners of the output obtained by algebraic summation of the angles (a_wyh) release and adjustment of the angles (a_ci), with adjustment angles (a_ci) is determined by the ratio of:

and_ci={c₁×[(h_i-h_b)/(H-h_b)]³+c₂×[(h_i-h_b)/(H-h_b)]²+c₃×[(h_i-h_b)/(H-h_b)]}×a_i,

where c₁- constant when the member of the third degree in the range -3,87÷0,0,

c₂- constant when the member of the second degree in the range +7,19÷0,0,

c₃- constant when the member first degree in the range -2,92÷0,0,

and_CIcorrective angle in degrees, algebraically summed with a fixed angle of output in the local cross-section of the blade,

h_b- lower limit of the height of the local pop the river cross-section of the blade, above which are corrected angles of output and which is separated from the height of the stub of the cross-section of 0.25-0.35-height blades,

h_i- local value of the height of the local cross-section of the blade, measured from the height of the stub cross-section,

H - the height of the shoulder,

a_WH- angle of entrance,

a_wyh- angle output

and_i- formed by the bending angle profile in degrees in the local cross-section of the blade, which is equal to the difference between a given entrance angle (a_WHand given the exit angle (a_wyh), measured from the axis of rotation propfan and_i=a_WH-a_wyh.

Birotational wincounter can be performed zaopatrzonym, i.e. to contain the outer shell.

In the cross section of the blades, the contour of which is selected aerodynamic profile, the cross section of skeletal surface is limited to the curved line inside the airfoil and having a bulge in the side of the back of the blade. The bending angle profile in the cross section of the blades is determined as the difference between the entrance angle and the exit angle of this curve, and these angles are measured relative to the axis of rotation propfan.

The use in the above f is rule to declare birotational propfan left boundary values of the constants c ₁÷c₃from their bands (c₁=-3,87, c₂=+7,19,₃=-2,92) leads to both blades of the impeller to the values of the correction angle and_cidecreasing from a maximum positive value at the periphery, constituting ≈0,40 correct bending angle profile and_iin the peripheral cross section of the blade, to 0.0 in cross section, spaced from the sleeve to 0.70 to 0.74 and the height of the blades, and to the minimum negative value, amounting to ≈-0,33 from the desired bending angle profile and_iin cross section, spaced from the sleeve 0.48-0.54-height blades, and then increasing to 0.0 in the boundary cross-section, spaced from the sleeve 0.25-0.35-height blades. For cross-sections located below this boundary section, correcting the angle a_cishould be set to 0.0.

The increase in the angles of output in peripheral areas due to the addition of the correction angle to the desired angle of the output at a constant angle of entry and, therefore, reducing the bending angle profile in the peripheral parts of the both blades of the impeller ensures reduction of the aerodynamic load profiles of peripheral areas and, as a consequence, the reduction of the disturbing influence of these sites on the ambient flow and the decrease in the intensity of trailing vortices generated e is their plots. Because a reduction in aerodynamic loading peripheral areas of blades causes and reduction of generated these plots the values of the degrees of increase of total pressure, to compensate for the shortage of the increase in total pressure in the peripheral areas of the blades at the same time increase the value of the degrees of the total pressure generated by the middle sections of the blades, which adequately increase the bend profile in these middle sections of the blades by subtracting the correction angle from the desired angle of the output at a constant angle of entry.

Due to the predominant role of aerodynamic loading peripheral areas of blades in the creation of the propfan noise reduction bend profiles in cross sections of peripheral areas of both blades of the impeller and the associated reduction in aerodynamic load profiles of these sites, despite adequate increase in the load profile cross-sections of the mid sections of the blades, causes the attenuated intensity of the aerodynamic interaction of the fields of the currents generated vozmushchaemym the influence of the impeller, and is particularly significantly attenuated the intensity of the interaction of trailing vortices from the blades of the first wheel and a second wheel blades and the intensity of usaimage the effects of trailing vortices from both blades of the wheels for the second impeller, and therefore, decreases the levels established in windowancestor noise.

At zero values of the constants c₁÷₃corresponding to the right edge of their range, correcting the angle a_cibecomes equal to 0.0 for peripheral and middle sections of the blades, and therefore disappears positive effect from the use of the claimed invention.

Additionally the essence of the invention is illustrated on the submitted drawings.

Figure 1 shows the form of impellers stated birotational propfan in the longitudinal section.

Figure 2 illustrates the kind of median skeletal surface of zero thickness for the blades of the first impeller.

On figa shows a local cross-section along a-a, figure 1, the blades of the first impeller on arbitrary local height of the scapula.

On figb shows a local cross-section along a-a, figure 1, the blades of the second impeller to an arbitrary local height of the scapula.

Figure 1 in longitudinal section stated birotational propfan shown arranged one after another the first impeller 1 and the second impeller 2, rotating in opposite directions about the axis 3 propfan. The blades 4 of the first impeller 1 and the blades 5 of the second impeller 2 may be the issue is lnany rotating respectively in the disks 6 and 7 relative to the radial axes 8 and 9 or is stationary in these disks. Input flange 10 and output edge 11 of the blade 4, and the input flange 12 and output edge 13 of the blade 5 can have varying along the height H of these blades form, which ensures the blades 4 and 5 direct or reverse sweep. For information, figure 1 shows the height H of the blades 4 of the first impeller 1 and the height H of the blades 5 of the second impeller 2, and the local height h_ilocation of cross-sections respectively in the blade 4 and the blade 5.

In the case of zakuporivanija birotational fan it can be equipped with outer cowling (engine) 14.

Figure 2 for example shows the skeleton surface 15 of zero thickness, which could be obtained by designing the blades, similar to the blade 4 of the first impeller 1. As can be seen from this figure, the distribution of the angles of the entrance to the skeletal surface and angles logoff provide a continuous decrease of the bending skeletal surface in the direction away from the sleeve 16 to the periphery 17.

On figa and 3b shows a local cross-section of the blades 4 of the first impeller 1 and the blades 5 of the second impeller 2, located on the local height h_ithese blades 4 and 5 (section a-a propfan, figure 1). Cross-section of the scaffold surface, which constitutes the basis of the blades 4, and the cross is the cross-section of skeletal surface, the basis of blades 5, are respectively curved lines 18 and 19, conducted by the strokes. The contours of cross-sections of the blades 4 and 5 are required to provide aerodynamic characteristics of airfoils 20 blades 4 and 21 of the blades 5. These airfoils 20 and 21 when profiling blades "dress up" respectively cross-sections 18 and 19 of the skeletal surfaces of the blades 4 and 5. For information on fega and 3b shows the entrance angles a_WHaccordingly, in the cross-section of skeletal surfaces of the blades 4 and blades 5 and the angles a_wyh+a_ciout of these cross-sections, as well as bend and_i-a_CItransverse sections of skeletal surfaces respectively of the blades 4 and 5. Entrance angles a_WHand angles of output a_wyh+a_ciare straight lines parallel to the axis 3 of the propfan. The angles a_i-a_cibending transverse sections of skeletal surfaces equal to the difference respectively between the entrance angle a_WHand the exit angle of a_wyh+a_ciblades 4 and between the entrance angle a_WHand the exit angle of a_wyh+a_CIthe blades 5 are at the same angles of bending, respectively, of the profiles 20 and 21 in the cross sections of the blades 4 and 5.

It is obvious that increasing the exit angle at a constant angle of entrance leads to mind is neseniyu bending angle profile in the cross section of the blades, and reducing the exit angle at a constant angle of entrance leads to an increase in bending angle profile.

Thus, the technical result of the claimed birotational windowancestor is because after the design process of the blades of the first and second impellers found distribution along the height of the blade angles of entrance and angles of their skeletal surfaces, providing the required distribution over the blades of degrees of increase of the total pressure airflow rates and efficiencies, distribution of exit angles are adjusted by algebraic summation of the angles of output and adjustment of the angles determined by the present value, to ensure reduction of bend angles of the profiles in the peripheral areas of blades and adequate increase in the bend of the profiles in the middle sections of the blades at a constant the corners of the entrance. The reduction of the bending angle profile in the peripheral parts of the both blades of the impeller reduces aerodynamic load profiles in peripheral areas and, consequently, to reduce disturbance of these sites on the ambient flow and the decrease in the intensity of trailing vortices generated by those sites. Due to the decrease in bend profiles shortfall degree of enhancement is the total pressure in the peripheral areas of blades is compensated by a simultaneous increase in degrees of increasing total pressure, created the middle sections of the blades due to the increase of the bend profile in these middle sections. As the aerodynamic load on the peripheral areas of blades plays a predominant role in the creation of the propfan noise, by reducing bend profiles in cross sections of peripheral areas of both blades of the impeller, despite adequately increased angles of bending profiles, cross-sections of the mid sections of the blades is achieved by weakening the intensity of the aerodynamic interaction of the fields of the currents generated vozmushchaemym the influence of the impeller, and especially a significant decrease in the intensity of interaction trailing vortices from the blades of the first wheel and a second wheel blades and intensity of interaction trailing vortices from both blades of the wheels for the second impeller, and therefore, reduced levels generated by windowancestor noise.

1. Birotational wincounter consisting of adjacent the first impeller and the second impeller with blades, in which the contours of cross-sections form the airfoils covering a given profiled skeletal surface of zero thickness, which is built on varying along the height of the blades of predetermined angles of entry, the specified angle is output and educated of their difference to bend profile, characterized in that both impellers to reduce the bending angle profile in the peripheral areas of the blades and increase the bending angle profile in the median areas of blades by changing the angle of the output at a constant angle of entrance, aerodynamic profile in the cross sections of the blades above the cross-section, spaced from the sleeve 0.25-0.35-height blades perform with modified corners of the output obtained by algebraic summation of the angles of output and adjustment of the angles (a_ci), with adjustment angles (a_ci) is determined by the ratio:
a_ci={c₁·[(h_i-h_b)/(H-h_b)]³+c₂·[(h_i-h_b)/(H-h_b)]²+c₃·[(h_i-h_b)/(H-h_b)]}·a_i;
where c₁- constant when the member of the third degree in the range -3,87÷0,0,
c₂- constant when the member of the second degree in the range +7,19÷0,0,
c₃- constant when the member first degree in the range -2,92÷0,0,
a_cicorrective angle in degrees, algebraically summed with a fixed angle of output in the local cross-section of the scapula,
h_b- lower limit of the height of the local cross-section of the blade, above which is the correction angles of output and furthest from the height is what I stub cross section 0,25-0,35 height of the scapula,
h_i- local value of the height of the local cross-section of the blade, measured from the height of the stub cross-section,
H - the height of the scapula,
a_i- formed by the bending angle profile in degrees in the local cross-section of the blade, which is equal to the difference between a given entrance angle and the desired angle of the output, measured from the axis of rotation propfan.

2. Birotational wincounter according to claim 1, characterized in that it is made zaopatrzonym.