A strengthened heat transfer structure for changing the local flow field of pneumatic thermal de-icing of blades

Abstract

The present invention belongs to the technical field of blade pneumatic thermal de-icing systems, and relates to a heat transfer enhancement structure for changing the local flow field of blade pneumatic thermal de-icing. The heat transfer enhancement structure is a strengthened heating section in the blade where the heat transfer intensity needs to be improved. A corrugated pipe section is provided in the strengthened heating section for changing the hot gas flow area in the strengthened heating section. The corrugated pipe section is composed of a front end face, a rear end face and a semi-cylindrical section. The distances from the front end face and the rear end face to the inner surface of the corresponding blade edge are the same. The corrugated pipe section is fixed on the first web in the blade, and the first web overlaps with the center of the corrugated pipe section. In the corresponding selected heat transfer enhancement area, by designing and setting a corrugated flow field structure in this area, the turbulence intensity of the hot gas flow in the corrugated flow area is improved, thereby enhancing the overall heat transfer effect between the hot gas flow and the leading edge of the middle section of the blade with a larger thickness. That is, on the basis of the original pneumatic thermal de-icing effect, the heating effect of the corresponding flow section is additionally improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of blade pneumatic thermal de-icing systems, and particularly relates to a heat transfer enhancement structure for changing the local flow field of blade pneumatic thermal de-icing. Background Art

[0002] Pneumatic thermal de-icing is a relatively common technology at present. However, due to the long length of the blade, there are problems of uneven thickness distribution to varying degrees in both the chordwise and spanwise directions of the blade. If only the single technology of pneumatic thermal de-icing is used for de-icing, the following problems exist: Although the icing situation on the blade is relatively serious, because the thickness is small, the heating effect of the hot air flow on the blade tip is good, making it not easy to have ice coverage at the blade tip; In contrast, in the middle section of the blade, especially the leading edge part, due to the large blade thickness, although there is a hot air flow inside, the heating effect is poor. Summary of the Invention

[0003] The purpose of the present invention is to provide a heat transfer enhancement structure for changing the local flow field of blade pneumatic thermal de-icing, which solves the problem of poor pneumatic thermal de-icing effect in the middle section of the blade.

[0004] The present invention is realized through the following technical solutions:

[0005] A heat transfer enhancement structure for changing the local flow field of blade pneumatic thermal de-icing, wherein the heat transfer enhancement structure is a strengthened heating section in the blade where the heat transfer intensity needs to be improved;

[0006] A corrugated pipe section is provided in the strengthened heating section for changing the flow region of the hot air flow in the strengthened heating section;

[0007] The corrugated pipe section is composed of a front end face, a rear end face, and a semi-cylindrical section, and the distances between the front end face and the rear end face and the inner surface of the corresponding blade edge are the same;

[0008] The corrugated pipe section is fixed on the first web in the blade, and the first web overlaps with the center of the corrugated pipe section.

[0009] Further, smooth tapered sections are connected to the front end and the end of the corrugated pipe section.

[0010] Further, a pair of flow channel baffles are symmetrically arranged on the tapered section connected to the front end of the corrugated pipe section for diverting more hot air flow to the flow field area near the leading edge angle point of the blade edge.

[0011] Further, the flow channel baffle forms an angle of 20° - 45° with the spanwise center line of the blade.

[0012] Further, when the strengthened heating section is arranged inside the blade leading edge, the flow area enclosed by the two flow channel baffles, the tapered section, and the inner surface of the blade leading edge accounts for 0.4 - 0.6 of the entire semi-circular ring-shaped flow area at the corresponding position.

[0013] Furthermore, the flow velocity of the hot air flow entering the front end face is increased by 2 to 3 times compared with that before the enhanced heating section is provided.

[0014] Furthermore, the corrugated pipe section is arranged inside the leading edge of the blade or between the first web and the second web inside the blade.

[0015] Furthermore, the shortest distance from any point on the surface of cross-section i of the corrugated pipe section parallel to the chord direction of the blade to the inner surface of the cross-section of the leading edge of the blade at the same position is the same.

[0016] Furthermore, the material of the corrugated pipe section is selected as a composite material the same as that of the blade.

[0017] Furthermore, the height of adjacent wave crests and wave troughs on the corrugated pipe section takes the same value, which is equal to 0.4 to 0.6 times the shortest distance between the corresponding corrugation and the cross-section of the leading edge of the blade.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] The present invention discloses a heat transfer enhancement structure for changing the local flow field of blade pneumatic thermal de-icing. In the corresponding selected heat transfer enhancement area, by designing and arranging a flow field structure in the shape of corrugations in this area, the turbulence intensity of the hot air flow in the corrugated flow-through area is improved, thereby enhancing the overall heat transfer effect between the hot air flow and the leading edge of the middle section of the blade with a larger thickness. That is, on the basis of the original pneumatic thermal de-icing effect, the heating effect of the corresponding flow section is additionally improved; the corrugated pipe designed by the present invention is semi-cylindrical instead of conical because if a conical shape is adopted, there will be a change in the flow-through area at the place where heat transfer needs to be enhanced. Although the flow velocity becomes faster downstream, it will lead to relatively poor heat transfer enhancement effect at the front end. Because the overall heating improvement effect of the heat transfer enhancement section is pursued, the present invention finally selects a cylindrical shape, which will achieve a better balance effect between the heating effect and the flow resistance; the middle section of the blade in the spanwise direction is the area where the pneumatic thermal effect of the blade is poor. In this area, the leading edge of the blade is prone to icing and needs heat transfer enhancement, but it is not limited to the leading edge only. For example, in the middle section of the blade adjacent to the leading edge, this situation may also exist, so this heat transfer enhancement structure can also be used for heat transfer.

[0020] Furthermore, in order to avoid additional pressure loss, vibration and other situations caused by the sudden change of the flow-through area of the hot air flow inside the leading edge of the blade, a smooth conical section is connected to the front end face of the corrugated pipe section. Similarly, a conical section is also connected to the end of the frustum flow field structure, avoiding the sudden change of the flow field before and after the hot air flow enters the frustum flow field structure.

[0021] Further, since the area near the leading-edge angle of attack point of the blade is a relatively more severe area among the blade leading edges with serious icing conditions, a pair of flow channel baffles are symmetrically arranged on the vertebral section at the front end of the corrugated pipe section. Through the flow channel baffles, more hot air flow is diverted to the flow field area near the leading-edge angle of attack point of the blade. By increasing the flow rate, more heat flow for ice melting is provided for the area near the leading-edge angle of attack point.

[0022] Further, the velocity of the hot air flow entering the corresponding flow-through cross-section of the front end face is increased to 2 - 3 times. In this way, a balance can be achieved between the increase in flow velocity and the pressure loss, and better economic benefits can be obtained.

[0023] Further, the material of the corrugated pipe section is selected as a composite material the same as that of the blade. While reconstructing the flow field in the area, the weight of the corrugated pipe section is reduced, and its influence on the unit load, etc. is decreased. Description of the Drawings

[0024] Figure 1 It is a structural diagram of gas-solid enhanced heat transfer in the gas-thermal enhanced heating section at the leading edge of the blade;

[0025] Figure 2 It is a schematic structural diagram of the corrugated pipe section;

[0026] Figure 3 It is a schematic diagram of the flow channel baffle at the front end of the corrugated pipe section.

[0027] 1: Leading edge of the blade; 2. Trailing edge of the blade; 3: First web; 4: Second web; 5: Leading-edge enhanced heating section; 6: Vertebral section; 7: Corrugated pipe section; 8: Front end face; 9: Rear end face; 10: Flow channel baffle; 11: Cross-section of the corrugated section. Detailed Implementation Manner

[0028] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further detailed description is given in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0029] The components described and shown in the drawings and embodiments of the present invention can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present invention provided in the following drawings is not intended to limit the scope of the claimed present invention, but only represents a selected embodiment of the present invention. Based on the drawings and embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present invention.

[0030] On the premise of limiting factors such as the output power of the device, the safety of the blade, and the overall operating economy, find the areas that need to be additionally improved in terms of gas-thermal heat transfer in the chordwise and spanwise directions of the blade. That is, instead of blindly achieving the de-icing effect of the difficult-to-heat blade areas by increasing gas-thermal de-icing operating parameters (such as flow rate and temperature), which are detrimental to blade safety and operating economy, the present invention uses normal and general operating methods to solve the de-icing requirements of the blade root and tip (preliminary conclusions for the blade icing area). For the middle part and (or) other areas of the blade, because the blade thickness or icing condition is relatively serious, the areas that need to enhance heat transfer are screened out, and local enhanced heat transfer structures are designed inside the above areas.

[0031] As Figure 1 shown, a strengthened heat transfer structure for changing the local flow field of blade gas-thermal de-icing designed by the present invention has the principle that a corrugated pipe section, that is, a corrugated pipe section 7, is arranged in the selected blade strengthened heat transfer section. The hot air flow with increased flow velocity is lifted by the diversion and guiding structure. Under the action of the corrugated flow channel on the surface of the corrugated pipe section 7, the turbulence intensity of the heat flow is increased, resulting in a corresponding increase in the heat transfer intensity.

[0032] Based on Figure 1 the structure shown, the leading edge strengthened heating section 5 that needs to enhance the heat transfer intensity is screened out in the whole blade, and its length is L1. In addition to the leading edge part, it may also include the remaining areas in the chordwise direction of the blade, such as the partial area between the first web 3 and the second web 4 of the blade. Its design method is similar to that of the blade leading edge section and is not drawn in Figure 1 .

[0033] As Figure 1 and Figure 2 shown, inside the leading edge 1 of the blade in this area, a built-in flow field changing structure of the corrugated pipe section 7 is designed to change the hot air flow area in the leading edge strengthened heating section 5. The corrugated pipe section 7 is composed of a front end face 8, a rear end face 9, and the corrugated surface between the two. The front end face 8 and the rear end face 9 are designed in the same shape. Considering the small change in the distance between them and the inner surface of the leading edge, corresponding dimensional modifications need to be made to the shape to ensure that the distances between the front end face 8 and the rear end face 9 and the corresponding inner surface of the leading edge are the same. Between the front end face 8 and the rear end face 9, it is enveloped with a corrugated surface in a corrugated shape. Finally, the corrugated pipe section 7 is fixed on the first web 3, and their centers overlap.

[0034] As Figure 1 shown, to avoid additional pressure loss and vibration caused by the sudden change in the flow area of the hot air flow inside the blade leading edge (i.e., the sudden contraction when entering the flow channel and the sudden expansion when flowing out of the flow channel), a smooth tapered section 6 is connected to the front end face 8 of the corrugated pipe section 7. Similarly, a tapered section ( Figure 1(not shown in the figure), which avoids the sudden change of the flow field of the hot air flow before and after entering the corrugated pipe section 7.

[0035] As Figure 2 shown, regarding the design of the corrugated pipe section 7, the front end face 8 and the rear end face 9 are directly connected with outward convex corrugations respectively, and the shape can be selected as semicircular or bow-shaped. The radius and height of this shape, as well as its distance from the inner surface of the leading edge, can carry out corresponding design and optimization from the starting point of strengthening heat transfer by combining numerical simulation methods. After determining the shape parameters, the concave and convex shapes alternate to form the entire corrugated surface.

[0036] As Figure 2 shown, on the cross-section 11 of the corrugated section, it can be seen that the heights of the adjacent wave crests and wave troughs on the corrugated pipe section 7 take the same value, which is equal to 0.4 - 0.6 times the closest distance between the corresponding corrugation and the cross-section of the blade leading edge.

[0037] In the present invention, the flow channel heights of the front end face 8 and the rear end face 9 from the blade leading edge are the same, that is Figure 3 r1 in. In order to improve the heat transfer effect of the hot air flow in the leading edge strengthening heating section 5, the flow velocity of the hot air flow is increased by 2 - 5 times compared with that in other regions of the leading edge without the leading edge strengthening heating section 5. In the present invention, the velocity of the hot air flow entering the corresponding flow-through cross-section of the front end face 8 is increased by 2 - 3 times, so that a balance can be achieved between the increase in flow velocity and the pressure loss, and better economic benefits can be obtained.

[0038] Since the area near the leading edge attack angle point of the blade is a relatively more serious area among the blade leading edges with more serious icing conditions, a pair of flow channel baffles 10 are symmetrically arranged at the vertebral section 6 in front of the corrugated pipe section 7, as Figure 3 shown. The function of the flow channel baffle 10 is to divert more hot air flow to the flow field area near the leading edge attack angle point of the blade, and provide more heat flow for melting ice in the area near the leading edge attack angle point by increasing the flow rate. The flow channel baffle 10 is distributed at a certain angle with respect to the blade spanwise center line, and can take values between 20° and 45°.

[0039] As Figure 3 shown, the two flow channel baffles 10 form a reduced flow channel at a certain angle, which is beneficial to introducing a higher proportion of heat flow into the middle area of the leading edge in the strengthening heat transfer section, and better solving the heat transfer requirements of the area where icing is more likely to form at the leading edge.

[0040] The flow area enclosed by the two flow path baffles 10, the conical section 6, and the inner surface of the blade leading edge 1, that is, the cross-sectional area at a specific position in the spanwise direction, accounts for 0.4 to 0.6 of the entire semi-circular annular flow area at the corresponding position. For example, at the position where the front end of the flow path baffle 10 is located, the area enclosed by the edge of the flow path baffle, the curved surface of the conical section 6, and the arc of the blade leading edge accounts for 0.6 of the semi-circular annular area here, while the area enclosed by the corresponding end of the flow path baffle accounts for 0.4 of the corresponding semi-circular annular area.

[0041] After determining the corrugated pipe section 7 according to the above method, the layout method of the flow path baffle 10 can be optimized in combination with the design of the flow path baffle 10.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: still can modify the specific implementation manners of the present invention or make equivalent replacements, and any modification or equivalent replacement without departing from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A strengthened heat transfer structure for changing the local flow field of pneumatic thermal deicing of blades, characterized in that, The enhanced heat transfer structure is an enhanced heating section in the blade where the heat transfer intensity needs to be improved; A corrugated pipe section (7) is arranged in the enhanced heating section for changing the hot gas flow region in the enhanced heating section; The corrugated pipe section (7) is composed of a front end face (8), a rear end face (9) and a semi-cylindrical section. The distances between the front end face (8) and the rear end face (9) and the inner surfaces of the corresponding blade edges are the same; The corrugated pipe section (7) is fixed on the first web (3) inside the blade, and the first web (3) overlaps with the center of the corrugated pipe section (7); Smooth tapered sections (6) are connected to the front end and the end of the corrugated pipe section (7); A pair of flow channel baffles (10) are symmetrically arranged on the tapered section (6) connected to the front end of the corrugated pipe section (7) for diverting more hot air flows to the flow field region near the leading edge angle point of the blade edge.

2. The enhanced heat transfer structure for changing the local flow field of blade pneumatic de-icing according to claim 1, characterized in that, The flow channel baffle (10) forms an angle of 20° - 45° with the blade spanwise center line.

3. A heat transfer enhancement structure for changing the local flow field of blade pneumatic de-icing according to claim 1, characterized in that, When the enhanced heating section is arranged inside the blade leading edge (1), the flow-through area enclosed by the 2 flow channel baffles (10), the tapered section (6) and the inner surface of the blade leading edge (1) accounts for 0.4 - 0.6 of the entire semi-circular ring flow-through area at the corresponding position.

4. A strengthened heat transfer structure for changing the local flow field of blade pneumatic thermal de-icing according to claim 1, characterized in that The flow velocity of the hot air flow entering the front end face (8) is increased by 2 - 3 times compared with the flow velocity before the enhanced heating section is not arranged.

5. The enhanced heat transfer structure for changing the local flow field of blade pneumatic thermal de-icing according to claim 1, characterized in that The corrugated pipe section (7) is arranged inside the blade leading edge (1) or between the first web (3) and the second web (4) inside the blade.

6. The enhanced heat transfer structure for changing the local flow field of blade pneumatic thermal de-icing according to claim 1, wherein The shortest distance from any point on the cross-section i surface parallel to the blade chord direction of the corrugated pipe section (7) to the inner surface of the cross-section of the blade leading edge (1) at the same position is the same.

7. A strengthened heat transfer structure for changing the local flow field of blade pneumatic thermal de-icing according to claim 1, characterized in that The material of the corrugated pipe section (7) is selected as a composite material the same as the blade material.

8. The enhanced heat transfer structure for changing the local flow field of blade pneumatic thermal de-icing according to claim 1, characterized in that, The heights of adjacent wave crests and wave troughs on the corrugated pipe section (7) take the same value, and the value is 0.4 - 0.6 times the shortest distance between the corresponding corrugation and the cross-section of the blade leading edge (1).

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