CN102927052B - Processing method for radial slot cartridge receiver - Google Patents

Abstract

The invention provides a processing method for a radial slot cartridge receiver, which synthetically considers structural features of a centrifugal compressor and internal flowing state. The position in a vane diffuser passenger, which is easy to have a stall phenomenon, is provided with a radial slot along the side of a wheel cover. The processing method is characterized by processing a coverage range of a slot along the radial direction and the slot depth by using the designed result of another processing method for a circumferential slot cartridge receiver, i.e., comprising the following steps of: designing a processing proposal for the circumferential slot cartridge receiver to determine the best slot depth and the coverage range of the processed slot along the radial direction; and designing the processing proposal for the radial slot cartridge receiver, wherein the radial slot is specifically a straight slot distributed along the radial direction in a discrete manner. The basic thinking for the design is that the trend and distance of the radial slot are expected to guide the trend of low-speed fluid at the side of the diffuser wheel cover, and a reflow passage for low-speed fluid is provided, therefore, the blockage of a top passage is weakened, a stable working range of the compressor is greatly improved, and simultaneously, the peak-value efficiency and small-flow lateral pressure ratio are improved.

Description

Radial groove treated casing method

Technical field

The present invention relates to a kind of centrifugal compressor treated casing method, particularly a kind of radial groove treated casing method.

Background technique

Centrifugal compressor has that volume is little, single-stage pressure ratio is high and advantages of simple structure and simple, is more and more applied to many fields.In recent years, along with the demand of people for microminiature energy conversion system and the continuous lifting of interest, high rotating speed, high pressure ratio, high efficiency, wide operating mode, miniaturization have become one of important trend of centrifugal compressor development, and have proposed day by day harsh requirement to its performance.The development trend of current gas compressor height rotating speed, high load is to the stable operation of gas compressor and expand steady technology and propose new challenge, and the UNSTEADY FLOW unstable phenomenon being particularly representative with rotating stall, surge is the key factor jeopardizing gas compressor stable operation.In the actual moving process of gas compressor, reach the minimum stream value on performance curve when flow after, reduce flow if continue, can there is unexpected change in gas compressor internal flow, stall group appears in runner inside, flows into instability status, and rotating stall occurs.Rotating stall is further to the development of the degree of depth, and compression system surge can occur, and causes the region occurring minus flow in compression system.

The generation of rotating stall can make impeller blade bear long vibration stress, cause the reduction of leaf longevity, and during surge generation, impeller blade and casing all will bear very large momentary force effect, larger destruction can be caused, therefore, safely and steadily run in order to ensure gas compressor, rotating stall and these two kinds of flow unstable phenomenons of surge must be avoided as far as possible.At present, general way allows gas compressor work under away from the state of stalling point, namely will consider certain stall margin in the design phase.But the efficient and high parameter operation area of typical gas compressor closes on the flow unstable border of gas compressor usually, the way of reserved certain stall margin is a kind of waste greatly concerning the performance of gas compressor.Therefore, for the gas compressor in practical application, usually wish that its stable operation range is wide as far as possible, working close to efficient and high parameter operation area to make gas compressor as far as possible.And widen the stable operation range of gas compressor, postpone the generation of air-flow stall, the Performance And Reliability tool improving gas compressor is of great significance, also become gas compressor design specialists and endeavour one of key issue solved.

As a kind of Passive Control strategy of gas compressor internal flow unstability, adopting treated casing (CasingTreatments) to weaken top clearance leakage flow to the negative effect of gas compressor by contributing to, improving the stall margin of gas compressor.The treated casing form of extensive use is various slot type treated casing structures, and traditional slot type treated casing structure is often carried out for compressor rotor, but is expanding the same decline that often can cause efficiency of gas compressor stable operation nargin.

Summary of the invention

The object of the invention is to the shortcoming overcoming above-mentioned prior art, provide a kind of can while increasing substantially gas compressor stable operation range, ensure peak efficiencies and the small flow side pressure radial groove treated casing method than the centrifugal compressor also increased.

For achieving the above object, the technical solution used in the present invention is:

1) first, do not have slotted gas compressor to carry out modeling to wheel cap side, and numerical simulation and flow analysis are carried out to its interior flow field, determine in gas compressor, to account for leading flow field structure and flow performance thereof, specify in compressor passage the region being easy to stall occurs;

2) secondly, region according to being easy to occur stall in the compressor passage that step 1) is determined is offered single peripheral groove along gas compressor wheel cap side and carries out modeling and numerical simulation to it in different meridian position, relatively the steady effect of expansion of diverse location peripheral groove casing and the impact on compressor efficiency thereof, determine best slotting position;

3) then, peripheral groove groove depth is fixed in the optimum position offering peripheral groove according to gas compressor wheel cap side, changes peripheral groove groove width, carries out modeling and numerical simulation to the peripheral groove of different in width, relatively groove width expands the impact of steady effect and compressor efficiency on peripheral groove casing, thus determines best groove width;

4) further, the best groove width that the optimum position of peripheral groove and step 3) obtain is offered according to gas compressor wheel cap side, fixing peripheral groove groove width, change peripheral groove groove depth, modeling and numerical simulation are carried out to the peripheral groove of different depth, relatively groove depth expands the impact of steady effect and compressor efficiency on peripheral groove casing, thus determines best groove depth;

5) last, according to step 2), 3), 4) the peripheral groove position determined, the groove depth of peripheral groove and groove width, extended laterally by peripheral groove position and offer identical peripheral groove, determine the spacing of the groove facewidth and adjacent slot, change peripheral groove number, modeling and numerical simulation are carried out to the peripheral groove casing of different slots number, compares peripheral groove number expands steady effect and compressor efficiency impact on treated casing, determine best peripheral groove number;

6), after peripheral groove number is determined, radial process groove coverage area is radially namely from the forward position of first peripheral groove to the rear edge of last one peripheral groove;

7) forward position of radial groove overlaps with the forward position of first peripheral groove, the rear edge of radial groove overlaps on the rear edge of peripheral groove together with last, and the degree of depth of radial groove chooses the best groove depth of above-mentioned peripheral groove, and radial groove has 17 groups, 17 blades of corresponding vane diffuser, often group comprises 3 radial grooves.

Described best slotting position, best groove depth, best groove width and best peripheral groove number are determined by following index:

Comprehensive stall margin improvement (Δ SM): $\mathrm{\ΔSM}=\frac{{\left(Q_{m,\mathrm{stall}}\right)}_{\mathrm{solid}}}{Q_{m,\mathrm{stall}}}\×\frac{{\mathrm{\ϵ}}_{\mathrm{tot},\mathrm{stall}}}{{\left({\mathrm{\ϵ}}_{\mathrm{tot},\mathrm{stall}}\right)}_{\mathrm{solid}}}-1$

Design point/peak point efficiency change (Δ η _des/peak):

In formula: Q _mand ε _totbe respectively mass flow rate and overall pressure tatio, subscript stall, des and peak represent stalling point, design point and peak efficiencies point respectively, parameter with subscript solid is real wall casing gas compressor parameter, the parameter of non-subscripting is processor box gas compressor parameter, utilizes These parameters also can the steady effect of expansion of quantitative analysis radial groove treated casing method.

Described radial groove advanced position place width is 4.47mm, and in group, adjacent slot spacing is 4.47mm, and the spacing of two adjacent groups groove is 8.95mm.

In radial groove treated casing method provided by the invention, the trend of radial groove and spacing can guide the trend of Diffuser wheel cap side low velocity fluid, and for low velocity fluid provides a return flow line, contribute to the blocking weakening top passageway, increased substantially the stable operation range of gas compressor, peak efficiencies and small flow side pressure are than also increasing simultaneously.

This casing processing method can realize processing easily, and can obtain larger stall margin improvement under the prerequisite of not losing compressor efficiency, therefore having certain meaning for improving Capability of Compressor, having very high social benefit and promotional value.

Accompanying drawing explanation

Fig. 1 is radial process groove schematic diagram.

Fig. 2 is with or without the flow-efficiency characteristic of treated casing small size centrifugal compressor when 85% design speed (30,000rpm).

Fig. 3 is with or without the flow-pressure ratio characteristic curve of treated casing small size centrifugal compressor when 85% design speed (30,000rpm).

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail.

1) first, do not have slotted gas compressor to carry out modeling to wheel cap side, and numerical simulation and flow analysis are carried out to its interior flow field, determine in gas compressor, to account for leading flow field structure and flow performance thereof, specify in compressor passage the region being easy to stall occurs;

2) secondly, region according to being easy to occur stall in the compressor passage that step 1) is determined is offered single peripheral groove along gas compressor wheel cap side and carries out modeling and numerical simulation to it in different meridian position, relatively the steady effect of expansion of diverse location peripheral groove casing and the impact on compressor efficiency thereof, determine best slotting position;

3) then, peripheral groove groove depth is fixed in the optimum position offering peripheral groove according to gas compressor wheel cap side, changes peripheral groove groove width, carries out modeling and numerical simulation to the peripheral groove of different in width, relatively groove width expands the impact of steady effect and compressor efficiency on peripheral groove casing, thus determines best groove width;

4) further, the best groove width that the optimum position of peripheral groove and step 3) obtain is offered according to gas compressor wheel cap side, fixing peripheral groove groove width, change peripheral groove groove depth, modeling and numerical simulation are carried out to the peripheral groove of different depth, relatively groove depth expands the impact of steady effect and compressor efficiency on peripheral groove casing, thus determines best groove depth;

5) last, according to step 2), 3), 4) the peripheral groove position determined, the groove depth of peripheral groove and groove width, extended laterally by peripheral groove position and offer identical peripheral groove, determine the spacing of the groove facewidth and adjacent slot, change peripheral groove number, modeling and numerical simulation are carried out to the peripheral groove casing of different slots number, compares peripheral groove number expands steady effect and compressor efficiency impact on casing, determine best peripheral groove number.After peripheral groove number is determined, treatment trough coverage area is radially determined immediately, that is: from the forward position of first groove to the rear edge of last a groove.

6) after above-mentioned steps completes, start the design of radial groove, the forward position of radial groove overlaps with the forward position of first peripheral groove, the rear edge of radial groove overlaps on the rear edge of peripheral groove together with last, the degree of depth of radial groove chooses the best groove depth of above-mentioned peripheral groove, radial groove has 17 groups, and 17 blades of corresponding vane diffuser, often group comprises 3 radial grooves.The radial groove advanced position place width of such generation is 4.47mm, and in group, adjacent slot spacing is 4.47mm, and the spacing of two adjacent groups groove is 8.95mm.

The present invention is best, and slotting position, best groove depth, best groove width and best peripheral groove number are determined by following index:

Comprehensive stall margin improvement (Δ SM): $\mathrm{\ΔSM}=\frac{{\left(Q_{m,\mathrm{stall}}\right)}_{\mathrm{solid}}}{Q_{m,\mathrm{stall}}}\×\frac{{\mathrm{\ϵ}}_{\mathrm{tot},\mathrm{stall}}}{{\left({\mathrm{\ϵ}}_{\mathrm{tot},\mathrm{stall}}\right)}_{\mathrm{solid}}}-1$

Design point/peak point efficiency change (Δ η _des/peak):

In formula: Q _mand ε _totbe respectively mass flow rate and overall pressure tatio, subscript stall, des and peak represent stalling point, design point and peak efficiencies point respectively, parameter with subscript solid is real wall casing gas compressor parameter, the parameter of non-subscripting is processor box gas compressor parameter, utilizes These parameters also can the steady effect of expansion of quantitative analysis radial groove treated casing method.

Design process according to above-mentioned radial groove treated casing method carries out processor box design to certain high rotating speed small size centrifugal compressor, and with its action effect of experimental verification.

The design parameter of this gas compressor is as shown in table 1.

Table 1 small size centrifugal compressor design parameter

The circumferential treatment trough groove depth of initial option is 2mm, and groove width is 2.5mm, and by expanding the comparative analysis of steady effect to different meridian positions circumference treatment trough, the circumferential treatment trough advanced position finally determined is R=84.75mm.

The research of the circumferential treatment trough degree of depth and widths affect is found: increase the raising that the degree of depth of circumferential treatment trough and width are all conducive to compressor stall nargin, but negative effect can be caused to compressor efficiency, therefore, the circumferential treatment trough degree of depth finally selected and width are respectively 2mm and 2.5mm.

The circumferential treatment trough number finally determined is 3, and the groove facewidth is 1.5mm, and now, radial process groove coverage area radially is also determined immediately, that is: advanced position is R=84.75mm, and back edge position is R=95.25mm, and the degree of depth is 2mm, as shown in Figure 1.

With or without treated casing compressor efficiency, pressure ratio characteristic curve when Fig. 2 and Fig. 3 is part rotating speed, experiment rotating speed is 30,000rpm, as can be seen from the figure, compared to real wall casing gas compressor (SolidCasing), after employing treated casing (Treated Casing), gas compressor stable operation nargin has greatly improved, and comprehensive stall margin improvement reaches 22.442%, simultaneously, peak efficiencies promotes 1.454%, and small flow side pressure is than also having obvious lifting.

The foregoing is only one embodiment of the present invention, is not whole or unique mode of execution, and the exchange of those of ordinary skill in the art by reading present disclosure to any equivalence that technical solution of the present invention is taked, is claim of the present invention and contains.

Claims (1)

1. a radial groove treated casing method, is characterized in that comprising the following steps:

1) first, do not have slotted gas compressor to carry out modeling to wheel cap side, and numerical simulation and flow analysis are carried out to its interior flow field, determine in gas compressor, to account for leading flow field structure and flow performance thereof, specify in compressor passage the region being easy to stall occurs;

2) secondly, according to step 1) region that is easy to occur stall in the compressor passage determined offers single peripheral groove along gas compressor wheel cap side and carries out modeling and numerical simulation to it in different meridian position, relatively the steady effect of expansion of diverse location peripheral groove casing and the impact on compressor efficiency thereof, determine best slotting position;

3) then, peripheral groove groove depth is fixed in the optimum position offering peripheral groove according to gas compressor wheel cap side, change peripheral groove groove width, modeling and numerical simulation are carried out to the peripheral groove of different in width, relatively groove width expands the impact of steady effect and compressor efficiency on peripheral groove casing, thus determines best groove width;

4) further, optimum position and the step 3 of peripheral groove is offered according to gas compressor wheel cap side) the best groove width that obtains, fixing peripheral groove groove width, change peripheral groove groove depth, modeling and numerical simulation are carried out to the peripheral groove of different depth, relatively groove depth expands the impact of steady effect and compressor efficiency on peripheral groove casing, thus determines best groove depth;

5) last, according to step 2), 3), 4) the peripheral groove position determined, the groove depth of peripheral groove and groove width, extended laterally by peripheral groove position and offer identical peripheral groove, determine the spacing of the groove facewidth and adjacent slot, change peripheral groove number, modeling and numerical simulation are carried out to the peripheral groove casing of different slots number, compares peripheral groove number expands steady effect and compressor efficiency impact on treated casing, determine best peripheral groove number;

6), after peripheral groove number is determined, radial process groove coverage area is radially namely from the forward position of first peripheral groove to the rear edge of last one peripheral groove;

7) forward position of radial groove overlaps with the forward position of first peripheral groove, the rear edge of radial groove overlaps on the rear edge of peripheral groove together with last, and the degree of depth of radial groove chooses the best groove depth of above-mentioned peripheral groove, and radial groove has 17 groups, 17 blades of corresponding vane diffuser, often group comprises 3 radial grooves;

Described best slotting position, best groove depth, best groove width and best peripheral groove number are determined by following index:

Comprehensive stall margin improvement $\left(\mathrm{\ΔSM}\right):\mathrm{\ΔSM}=\frac{{\left(Q_{m,\mathrm{stall}}\right)}_{\mathrm{solid}}}{Q_{m,\mathrm{stall}}}\×\frac{{\mathrm{\ϵ}}_{\mathrm{tot},\mathrm{stall}}}{{\left({\mathrm{\ϵ}}_{\mathrm{tot},\mathrm{stall}}\right)}_{\mathrm{solid}}}-1$

Design point/peak point efficiency change $\left({\mathrm{\Δ\η}}_{\mathrm{des}/\mathrm{peak}}\right):\mathrm{\Δ}{\mathrm{\η}}_{\mathrm{des}/\mathrm{peak}}=\frac{{\mathrm{\η}}_{\mathrm{des}/\mathrm{peak}}}{{\left({\mathrm{\η}}_{\mathrm{des}/\mathrm{peak}}\right)}_{\mathrm{solid}}}-1$

In formula: Q _mand ε _totbe respectively mass flow rate and overall pressure tatio, subscript stall, des and peak represent stalling point, design point and peak efficiencies point respectively, parameter with subscript solid is real wall casing gas compressor parameter, the parameter of non-subscripting is processor box gas compressor parameter, utilizes the steady effect of expansion of These parameters also quantitative analysis radial groove treated casing method;

Described radial groove advanced position place width is 4.47mm, and in group, adjacent slot spacing is 4.47mm, and the spacing of two adjacent groups groove is 8.95mm.