Impeller structure for widening pressure ratio and flow range of gas compressor

Abstract

The invention provides an impeller structure for widening the pressure ratio and flow range of a gas compressor, which is a semi-open impeller and comprises a wheel disc, a wheel shaft and blades, the wheel shaft is arranged in the middle of the wheel disc, and the blades are evenly arranged between the wheel shaft and the wheel disc with the wheel shaft as the center. The blades comprise the main blades and the auxiliary blades, the auxiliary blades are arranged between the two main blades, and the height of the main blades is larger than that of the auxiliary blades. According to the wing-shaped swept impeller, the front edge of the blade is subjected to swept-forward design, the front edge molded line is subjected to optimization design on the basis, so that the wing-shaped swept impeller is formed, the pressure ratio and the flow range of a gas compressor can be effectively widened, and the purpose of meeting engineering requirements is achieved.

Description

Technical Field

[0001] The invention belongs to the field of turbocharging, and in particular relates to an impeller structure for widening the pressure ratio and flow range of a compressor. Background Art

[0002] Blade sweep was first applied in axial compressors in the early 20th century, and many related studies have been conducted so far. Early studies on the blade sweep effect used blade sweepback to improve performance. Hah et al. found that blade sweep and sweepback had little effect on fan efficiency, but blade sweep forward could increase the fan stall margin. Sweepback reduces the fan stall margin. Jang et al. optimized a transonic axial compressor by bending, tilting, and sweeping the blades. The optimal impeller internal flow separation and shock wave intensity were reduced, and the efficiency was improved. Among them, blade bending is the most effective way to improve impeller efficiency. Compared with axial compressors, research on the aerodynamic effect of centrifugal compressor blade leading edge sweep is relatively limited. Hazby et al. found that forward sweep can obtain higher efficiency and a wider range of stable operating conditions, while sweepback is the opposite. Krain et al. obtained higher efficiency and greater blockage flow by sweeping the leading edge of the blade. Ganes et al. found that the sweep effect is related to the sweep angle by changing different forward and backward sweep angles, and forward and backward sweeping have their own advantages. Xu et al. found that the leading edge inclination of centrifugal impeller blades has a great influence on the performance of the impeller. Both forward and backward inclination can improve the maximum efficiency of the impeller, but the efficiency is the highest when the blades are backward, and the range of stable operating conditions is the largest when the blades are forward.

[0003] At present, the research on the swept leading edge of the blade is relatively mature, and the research objects are all in the form of straight leading edge profiles, and no research has been carried out on the design optimization of the leading edge profile. Through research, it is found that compared with unswept impellers or forward-swept impellers, airfoil-swept impellers will significantly improve the performance of the compressor. Summary of the invention

[0004] In view of this, the present invention aims to propose an impeller structure that can broaden the pressure ratio and flow range of the compressor, so as to meet the requirements of the supercharger for high pressure ratio and wide flow range. The leading edge of the blade is designed to be swept forward, and the leading edge profile is optimized on this basis to form an airfoil sweep. The airfoil swept impeller can effectively broaden the pressure ratio and flow range of the compressor, thereby achieving the purpose of meeting engineering requirements.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] An impeller structure for widening the pressure ratio and flow range of a compressor is a semi-open impeller, comprising a wheel disc, a wheel shaft and blades;

[0007] The wheel axle is arranged in the middle of the wheel disc, and the blades are evenly arranged between the wheel axle and the wheel disc with the wheel axle as the center;

[0008] The blades include a main blade and an auxiliary blade. The auxiliary blade is arranged between two main blades, and the height of the main blade is greater than that of the auxiliary blade.

[0009] Furthermore, the leading edge of the main blade is swept forward by 10°.

[0010] Furthermore, the forward-swept end surface of the main blade is a double-wave structure.

[0011] Furthermore, the diameter of the impeller is 90-150 mm.

[0012] Compared with the prior art, the impeller structure for widening the compressor pressure ratio and flow range described in the present invention has the following advantages:

[0013] The present invention discloses an impeller structure for widening the pressure ratio and flow range of a compressor. The leading edge of the blade is designed to be swept forward, and on this basis, the leading edge profile is optimized to form an airfoil sweep. The airfoil swept impeller can effectively widen the pressure ratio and flow range of the compressor, thereby achieving the purpose of meeting engineering requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0015] Figure 1 A cross-sectional view of an impeller structure for widening the compressor pressure ratio and flow range according to an embodiment of the present invention;

[0016] Figure 2 It is a three-dimensional schematic diagram of an impeller structure for widening the compressor pressure ratio and flow range according to an embodiment of the present invention;

[0017] Figure 3 It is a schematic diagram of the meridian plane structure of the unswept, forward-swept and airfoil-swept impellers according to the embodiments of the present invention;

[0018] Figure 4 A schematic diagram of the angle distribution of the airfoil swept impeller according to an embodiment of the present invention;

[0019] Figure 5 A schematic diagram of thickness distribution of an airfoil swept impeller according to an embodiment of the present invention;

[0020] Figure 6 This is a schematic diagram of the meridian angle distribution of the airfoil swept impeller according to an embodiment of the present invention;

[0021] Figure 7 A schematic diagram comparing pressure ratio characteristic curves of the swept airfoil, the swept-leading-edge blade shape and the unswept blade shape according to an embodiment of the present invention;

[0022] Figure 8 A schematic diagram comparing the efficiency characteristic curves of the swept airfoil, the front-edge swept blade and the unswept blade according to an embodiment of the present invention;

[0023] Fig. 9 It is a schematic diagram of the isosurface of the blade along the flow channel direction according to an embodiment of the present invention;

[0024] Fig.10 It is a schematic diagram of the distribution contour lines of relative Mach numbers at different blade heights in the flow channel according to an embodiment of the present invention;

[0025] Fig.11 Schematic diagram of static entropy distribution of pressure surface and suction surface of two blade shapes according to an embodiment of the present invention;

[0026] Fig.12 Schematic diagram of total pressure distribution at the outlet of two impeller blade shapes according to an embodiment of the present invention;

[0027] Fig.13 It is a schematic diagram comparing the loading of 60% leaf height of two leaf shapes according to an embodiment of the present invention.

[0028] Description of reference numerals:

[0029] 1. Wing sweep. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0033] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0034] An impeller structure that broadens the compressor pressure ratio and flow range is a semi-open impeller, such as Figure 1 Figure 2 As shown, it includes a wheel disc, a wheel shaft and blades;

[0035] The wheel axle is arranged in the middle of the wheel disc, and the blades are evenly arranged between the wheel axle and the wheel disc with the wheel axle as the center;

[0036] The blades include a main blade and an auxiliary blade. The auxiliary blade is arranged between two main blades, and the height of the main blade is greater than that of the auxiliary blade.

[0037] Preferably, the leading edge sweep angle of the main blade is 10°.

[0038] Preferably, the swept-forward end surface of the main blade is a double-wave structure.

[0039] The following are the basic parameters of the airfoil swept impeller: Unit: mm

[0040] Hub diameter 24 Inlet diameter 82.35 Impeller height 50 Outlet diameter 135 Impeller outlet width 6.72

[0041] Examples, such as Figure 3-Figure 6 As shown,

[0042] Experimental comparison between an impeller with unswept blades, an impeller with pure forward-swept blades, and an impeller with airfoil-swept blades:

[0043] The inlet airflow angle is 60.824°, the back bend angle is 39.057°, the main impeller is selected with a diameter of 130-140mm, the impeller speed setting value is 70000rpm, the flow rate and pressure ratio of the impeller with no swept blades, the impeller with simple forward swept blades, and the airfoil swept impeller;

[0044]

[0045]

[0046] Impeller with unswept blades

[0047] Speed flow Pressure ratio 70000 1.2951 2.3037 70000 1.2814 2.5166 70000 1.2389 2.7304 70000 1.1667 2.9435 70000 1.1021 3.0878 70000 1.0586 3.1596 70000 1.2951 2.3037

[0048] Impeller with simple forward-swept blades

[0049] Speed flow Pressure ratio 70000 1.2483 2.2681 70000 1.2441 2.49 70000 1.2335 2.7264 70000 1.2039 2.9635 70000 1.1553 3.1129 70000 1.1191 3.1855

[0050] Airfoil swept impeller

[0051] From the above experimental data, it can be seen that the swept airfoil impeller is more adaptable to the inlet flow, improves the shock wave shape at the impeller inlet, reduces flow loss, and brings about efficiency improvement;

[0052] like Figure 7 Figure 8 As shown, with the increase of speed, the pressure ratio increases more and more obviously, increasing by 2% at 50,000 rpm, 3.8% at 60,000 rpm, and 4.6% at 70,000 rpm. The peak efficiency of the compressor has also been improved to a certain extent, increasing by 2% at 50,000 rpm, and 2.2% at 60,000 rpm. At a high speed of 70,000 rpm, the peak efficiency of the airfoil-swept blade compressor is about 3.2% higher than that of the tip-swept compressor. For surge margin, the airfoil-swept blade has a wider surge margin than the tip-swept and unswept blades.

[0053] In order to further analyze the internal flow, the swept blade shape of the airfoil and the forward swept blade shape of the leading edge tip were compared at the highest efficiency operating point of 70,000 rpm, and a detailed flow field analysis was performed on the flow at the leading edge.

[0054] According to the swept-forward characteristics of the leading edge of the blade, four isosurfaces are divided along the blade height direction, such as Fig. 9 As shown, the flow characteristics of the leading edge of the blade are analyzed;

[0055] Fig.10 The Mach number distribution of four flow channels along the blade height isosurface (comparison between airfoil sweep and leading edge blade tip forward sweep). It can be seen from the figure that with the decrease of the blade height isosurface, the Mach number decreases. Compared with the leading edge forward swept blade shape, on the same blade height isosurface, the shock wave intensity of the airfoil swept blade shape is significantly reduced. Below 50% blade height, the airfoil swept blade shape inlet velocity is already lower than 1 Mach. This shows that the use of airfoil sweep can improve the shock wave form at the inlet and effectively improve the flow state at the impeller inlet.

[0056] Fig.11 It is the distribution form of static entropy on the pressure and suction surfaces of the two blade shapes. From the perspective of static entropy distribution, the two blade shapes have basically the same distribution form on the pressure surface. The static entropy of the swept airfoil impeller in the middle of the wheel is slightly lower than that of the swept airfoil at the leading edge. From the perspective of entropy increase, it is reflected that the static entropy value at this position is lower, the flow loss is smaller, and the efficiency characteristics can be improved and enhanced.

[0057] from Figure 7 The change in pressure ratio characteristics shows that the swept airfoil can significantly improve the pressure ratio. The total pressure at the impeller outlet is a factor of measurement. Therefore Fig.12 The total pressure distribution of the two blade outlets is given. From the total pressure distribution, the pressure distribution form of the two blades is basically the same.

[0058] Fig.13 It is a comparison of loading at 60% blade height of the two blade shapes, which can generally reflect the improvement of the airfoil sweep characteristics. At the inlet position, there is a sudden change in static pressure on the suction side of the blade, and the airfoil sweep is lower, indicating that the shock wave intensity is reduced. The static pressure airfoil sweep at the outlet position is slightly higher than the leading edge swept blade shape, indicating that the leading edge airfoil sweep has a certain degree of improvement on the pressure ratio.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An impeller structure for widening the compressor pressure ratio and flow range is a semi-open impeller, characterized in that: Including wheel disc, wheel axle and blades; The wheel axle is arranged in the middle of the wheel disc, and the blades are evenly arranged between the wheel axle and the wheel disc with the wheel axle as the center; The blades include a main blade and an auxiliary blade. The auxiliary blade is arranged between two main blades, and the height of the main blade is greater than that of the auxiliary blade.

2. The impeller structure for widening the compressor pressure ratio and flow range according to claim 1, characterized in that: The leading edge of the main blade is swept forward by 10°.

3. The impeller structure for widening the compressor pressure ratio and flow range according to claim 1, characterized in that: The forward-swept end surface of the main blade is a double-wave structure.

4. The impeller structure for widening the compressor pressure ratio and flow range according to claim 1, characterized in that: The diameter of the impeller is 90-150 mm.

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