CN103016380A - Method and device for determining performance of blade tip clearance region of cooling fan of automobile engine - Google Patents

Abstract

The invention discloses a device for testing performance of a blade tip clearance region of a cooling fan of an automobile engine with a flow guide ring. The device is characterized in that an outlet of an auxiliary fan is communicated with the inlet end of an air chamber test bed; the outlet end of the air chamber test bed is provided with a tested device; an inner cavity of the air chamber test bed is sequentially provided with a front air deflector, a spray nozzle and a rear air deflector along the direction from the inlet end to the outlet end; the auxiliary fan is sequentially connected with a frequency converter and a calculating system by signals; the calculating system is respectively connected with a static pressure difference measurement device and a motor speed regulation device by signals; the motor speed regulation device is connected with a motor by a signal; the tested device comprises the flow guide ring and a seal disc which are fixedly connected together; the periphery of the flow guide ring is provided with an air guide sleeve; and the seal disc is in transmission connection with a motor rotating shaft of the motor. The invention also discloses a method for testing performance of the blade tip clearance region of the cooling fan of the automobile engine with the flow guide ring. Due to utilization of the device, the experimental period is short and detection accuracy is high.

Description

The performance in automobile engine cooling fan blade tip clearance zone is determined method and device

Technical field

The invention belongs to automobile technical field, relate to a kind of performance testing device of the automobile engine cooling fan blade tip clearance zone with guide ring, the performance that the invention still further relates to a kind of automobile engine cooling fan blade tip clearance zone with guide ring is determined method.

Background technique

The leakage flow that blade tip clearance causes is one of flow phenomenon important in the axial turbomachine, and tip leakage flows and can cause degradation under adverse current, leakage flow, generation noise, flow losses increase, the mechanical efficiency is occuring near the radial clearance.Further investigation in this respect is to the Complex Flows significant [1] [2] [3] [4] [5] [6] [7] [8] [9] of overall understanding turbomachine inside.Generally in the devices such as aerostatic press, turbine, axial-flow pump, the maximum functional static pressure is about 1.0 * 10 ²~ 3.0 * 10 ⁴Kpa, clearance height is in the scope of 0.1 ~ 0.6mm.Early stage research mainly is to carry out in this scope.But the work static pressure of automobile engine cooling fan is very little, and the blade tip clearance zone is also larger, and this research field from other turbomachine blade tip clearance zones has significantly different.Automobile engine cooling fan blade tip clearance zone is to be 50 ~ 250kpa in static pressure, and clearance height is in the scope of 3 ~ 20mm.Therefore, may not be suitable in automobile engine cooling fan the achievement in research that obtains in early days.

For automobile engine cooling fan, exist certain radial clearance between the guide ring of fan and the fan dome, leaf top leakage flow phenomenon occurs easily.Flow mechanism for clear and definite automobile engine cooling fan blade tip clearance zone leakage vortex reduces the leakage flow that occurs between air guide sleeve and guide ring, reduces aerodynamic noise, significantly improves the problems such as automobile engine cooling fan aeroperformance.In addition, in the design of existing automobile engine cooling fan, mostly rely on the means of air compartment (air channel) test to verify and solve the fan aeroperformance, it is longer that this mode implements testing expenses costliness, cycle, and design cost is high.

On the other hand, at present in the test of tip clearance on the fan performance impact for automobile engine cooling fan, do not mention one the cover full and accurate effective performance determine method and device thereof, determine that specially the fluidal texture in automobile engine cooling fan blade tip clearance zone is to the size [10] [11] [12] [13] of performance impact.

Summary of the invention

The objective of the invention is, a kind of performance testing device of the automobile engine cooling fan blade tip clearance zone with guide ring is proposed, solved in the prior art, mostly rely on the means of air compartment (air channel) test to verify the aeroperformance of cooling fan, the problem of performance that can not Measurement accuracy blade tip clearance zone.

Another object of the present invention is, the performance that proposes a kind of automobile engine cooling fan blade tip clearance zone with guide ring is determined method, solved in the prior art, the means that mostly rely on air compartment (air channel) to test are verified the aeroperformance of cooling fan, can only be represented by the fan performance curve (only comprising flow rate pressure, flow-power and flow-relationship between efficiency), can not accurately express the problem of the performance in blade tip clearance zone.

The technical solution adopted in the present invention is, a kind of performance testing device of the automobile engine cooling fan blade tip clearance zone with guide ring, comprise air compartment test stand and accessory fan, atmosphere is led in the import of accessory fan, the entrance point UNICOM of the outlet of accessory fan and air compartment test stand; Be provided with tested device at air compartment test stand outlet end, atmosphere is led in the air outlet of tested device; The inner chamber of air compartment test stand is disposed with front current plate, nozzle and rear current plate along entrance point to the outlet end direction;

Described accessory fan is connected with frequency variator, computing system successively signal, and computing system is connected with the motor speed control device signal with the differential static pressure measuring device respectively in addition, and motor speed control device is connected with the motor signal;

Described tested device comprises guide ring and the seal disc that is fixed together, and the periphery of guide ring is equipped with air guide sleeve, and seal disc is connected with the motor passback shaft drive of motor.

Another technological scheme of the present invention is, a kind of performance of the automobile engine cooling fan blade tip clearance zone with guide ring is determined method, utilizes above-mentioned tested device, specifically may further comprise the steps:

Under the standard operation state, namely external pressure is that a standard atmospheric pressure, ambient temperature are that 20 ℃, relative moisture are 50%, air density is 1.2kg/m ³Tested device is controlled under the constant rotating speed, come the rotating speed of regulating and controlling accessory fan by frequency variator, regulate tested device import and outlet static pressure under the different flow, air stream is when nozzle, it is poor to have produced static pressure before and after nozzle, obtains static pressure difference value by the differential static pressure measuring device;

The work static pressure of tested device is adjusted in 50Pa～250Pa scope carries out applied voltage test, simultaneously, the largest circumference speed of the guide ring in tested device blade tip clearance zone is set to U=47.4m/s, one of the flow leakage rate group of dimensionless number certificate in prediction on such basis, thereby obtain the aeroperformance curve in tested device blade tip clearance zone.

The invention has the beneficial effects as follows: can avoid the leakage flow in main flow zone on the impact of aeroperformance, the important function that more accurate calculating blade tip clearance leakage rate plays; By apparatus of the present invention, can completely provide the performance curve in automobile engine cooling fan blade tip clearance zone.

Description of drawings

Fig. 1 is the car engine cooling system schematic representation of prior art;

Fig. 2 is the schematic representation that concerns of automobile engine cooling fan structure and flow characteristic;

Fig. 3 is two the structural model figure that separate fin embodiment in blade tip clearance zone;

Fig. 4 is three the structural model figure that separate fin embodiment in blade tip clearance zone;

Fig. 5 is five the structural model figure that separate fin embodiment in blade tip clearance zone;

Fig. 6 is the structural representation of performance testing device in the automobile engine cooling fan blade tip clearance zone of band guide ring of the present invention;

Fig. 7 is the schematic cross-section of the performance test test zone in the inventive method;

Fig. 8 is the flowing state model sketch in the inventive method blade tip clearance zone of adopting;

Fig. 9 is the experimental performance curve of the guide ring state of rest inferior lobe top gap area that obtains of the inventive method;

Figure 10 is the experimental performance curve of the guide ring rotation motion state inferior lobe top gap area that obtains of the inventive method.

Among the figure, 1. motor support base, 2. motor, 3. fan blade, 4. air guide sleeve, 5. radiator, 6. guide ring, 7. wheel hub is 8. separated fin, 9. expansion chamber, 10. seal disc, 11. motor speed control devices, 12. computing systems, 13. frequency variator, 14. accessory fans, 15. front current plates, 16. rear current plate, 17. nozzles, 18. differential static pressure measuring devices.

Embodiment

The automobile engine cooling fan with guide ring of prior art is installed with a guide ring jointly in all cooling fan blade outer ends.

With reference to Fig. 1, it is the car engine cooling system schematic representation of prior art, comprise the motor 2 that is arranged on the motor support base 1, motor 2 and 3 coaxial connections of cooling fan, cooling fan 3 cylindricals are provided with air guide sleeve 4(and have formed the blade tip clearance zone between the fixed guide rings of air guide sleeve and blade tip), the direction of facining the wind of cooling fan 3 is provided with radiator 5.

With reference to Fig. 2, be the schematic representation that concerns of automobile engine cooling fan structure and flow characteristic, be the blade tip clearance zone between the fixed guide ring 6 in cooling fan 3 blade outer ends and air guide sleeve 4, produce leaf top leakage flow.

With reference to Fig. 3, Fig. 4, Fig. 5, the performance testing device in the automobile engine cooling fan blade tip clearance zone of band guide ring of the present invention has carried out respectively three kinds of embodiments' structured testing.The arc section in the zone, gateway of guide ring is same radius and radian is equidistant value in three groups of example structure, the arc section in the zone, gateway of guide ring is same radius and radian in three groups of structures, the section length L is 49.7mm, and the span l and the S that separate fin are equidistant value.

Such as Fig. 3 embodiment, the structure in blade tip clearance zone is for straight-through U-groove bevel (namely separate fin 8 and comprise each one of front and back), and is simple in structure, installs easily, is widely used in the present automobile engine cooling fan.

Such as Fig. 4 embodiment, the structure in blade tip clearance zone is similar to the labyrinth sealing groove, the interval of U-groove bevel can be regarded as by three separation fins 8 and form two expansion chambers, it is 3mm that ε is got in the gap of the cylindric inwall of air guide sleeve and separation fin top, section length L=49.7mm, the diameter D=362mm of guide ring; The span S=21.6mm that separates fin, the fin thickness δ 1=2.5mm at entrance and exit place, middle fin thickness δ 2=1.5mm.

Such as Fig. 5 embodiment, the structure in blade tip clearance zone is separated the labyrinth sealing groove that fin 8 forms by five, and five radial heights of separating fin are consistent, and the guide ring end height is consistent, and it is 3mm that ε is got in the gap of the cylindric inwall of air guide sleeve and separation fin top.

Such as Fig. 6, the performance testing device in the automobile engine cooling fan blade tip clearance zone of band guide ring of the present invention, design [14] [15] [16] [17] according to the air compartment air inlet test requirements document in the CNS (GB/T1236-2000), be used for carrying out the performance test in motor car engine blade tip clearance zone

This testing apparatus comprises air compartment test stand and accessory fan 14, and atmosphere is led in the import of accessory fan 14, the entrance point UNICOM of the outlet of accessory fan 14 and air compartment test stand; Be provided with tested device at air compartment test stand outlet end, atmosphere is led in the air outlet of tested device; The inner chamber of air compartment test stand is disposed with front constant-current stabilizer 15, multiinjector flowmeter 17 and rear constant-current stabilizer 16 along entrance point to the outlet end direction;

Accessory fan 14 is connected with frequency variator 13, computing system 12 successively signal, and computing system 12 is connected signal with differential static pressure measuring device 18 respectively in addition and is connected with motor speed control device.Computing system 12 adopts various sensors to realize that physical signalling is to the conversion of electrical signal, send into computer by Interface Terminal, the parameters such as pressure, temperature, humidity are converted to digital quantity by data collecting card with the analog amount variable signal and send into computer, and rotating speed, power use communication converter to send into computer [18] [19].

(tested device that will originally install is changed to seal disc 10), tested device comprises that guide ring 6 is fixedly connected with seal disc 10, be fixedly connected with and fit together, can avoid like this leakage flow in main flow zone on the impact of performance, calculate comparatively accurately the blade tip clearance leakage flow.The periphery of guide ring 6 is equipped with air guide sleeve 4, and the internal-and external diameter location tolerance of air guide sleeve 4 and guide ring 6 is controlled at ± 0.1mm, and as shown in Figure 7, seal disc 10 is connected with the motor passback shaft drive of motor 2, and motor 2 is connected with motor speed control device 11 signals.

The performance in the automobile engine cooling fan blade tip clearance zone with guide ring of the present invention is determined method, utilizes above-mentioned tested device, with reference to Fig. 6, Fig. 7, specifically may further comprise the steps:

Under the standard operation state, namely external pressure is that a standard atmospheric pressure (101325Pa or 760mmHg), ambient temperature are that 20 ℃, relative moisture are 50%, air density is 1.2kg/m ³Tested device is controlled under the constant rotating speed, come the rotating speed of regulating and controlling accessory fan 14 by frequency variator 13, regulate tested device import and outlet static pressure under the different flow, air stream is when nozzle 17, air-flow forms local contraction at nozzle 17 places, flow velocity increases, and static pressure reduces, so produced static pressure poor (or claiming pressure reduction) in nozzle 17 front and back, air velocity is larger, and the pressure reduction that produces in nozzle 17 front and back is also larger.By measuring pressure reduction, just can weigh the size that flow is crossed nozzle 17 flows, obtain static pressure difference value by differential static pressure measuring device 18, this method of measurement is take law of conservation of energy and mobile equation of continuity as basis [20].The work static pressure of automobile engine cooling fan is 250Pa usually to the maximum, therefore, pressure is adjusted in 50Pa～250Pa scope and carries out applied voltage test, simultaneously, the winding number of automobile engine cooling fan is 2500rpm usually to the maximum, like this, and the largest circumference speed U=47.4m/s of the guide ring 6 in tested device blade tip clearance zone, calculate one group of dimensionless number certificate of flow leakage rate, thereby obtain the aeroperformance curve in tested device (device) blade tip clearance zone.

In addition, can also be provided with the air-flow constant-current stabilizer in apparatus of the present invention, be provided with altogether upper and lower sides two covers, the upstream side constant-current stabilizer is used for absorbing the kinetic energy of upstream side air-flow, the purposes of downstream side constant-current stabilizer is that air-flow is substantially uniform before the measuring plane in order to ensure entering, for satisfying these requirements, need in air compartment test stand runner, add the composite set (not showing among the figure) of some filter screens or perforated plate.

Theoretical calculation method of the present invention is the sealing principle according to the Steam Turbine in Fire Power Plant packing, between the guide ring of automobile engine cooling fan and air guide sleeve, form a series of throttle clearance and expansion cavity, force air-flow to pass through tortuous approach, produce throttling and thermomechanical effect, increase flow resistance with the method that expands step by step and suppress to leak the aeroperformance that improves fan.Fig. 8 is blade tip clearance zone labyrinth gland internal flow model schematic representation, packing is comprised of the separation fin and the expansion chamber that are arranged in order among the figure, at the some separation fins of the hard-wired guide ring processing of fan leaf tip portion, separate and keep less radial clearance between fin and the air guide sleeve, separate expansion chamber of formation between fin for per two.Air-flow flows to low voltage side from the high pressure side, and during gap by annular and separation fin end and air guide sleeve, aisle spare diminishes, and speed increases, pressure decreased, and simultaneous temperature reduces (enthalpy minimizing).Air-flow flows into the expansion chamber of separating the back sudden enlargement of fin end subsequently, it is large that flow area becomes suddenly, air-flow forms eddy current in expansion chamber, flow velocity is approximate to drop to zero, but pressure is constant, and its kinetic energy all is converted into heat energy, because the heat dissipating capacity of expansion indoor air flow is compared very little with the total amount of heat of air-flow, can ignore, so the air-flow enthalpy returns to again original numerical value, this process is called throttling process.When it passed through next gap, said process repeated.The overall presure drop of air-flow reduces in all separation fin clearances and expansion chamber successively gradually before and after the packing, is repeating throttling process, until pressure reduction is zero, air-flow in the end in expansion chamber pressure reach consistent with low voltage terminal pressure, leakage current no longer.But this is the leakage flow of blade tip clearance zone under a kind of perfect condition.

The leakage rate in the blade tip clearance zone under the perfect condition can be calculated with formula (1) or (2).Subscripting i=1 can be used, many groups formula simultaneous solution of 2,3... in the blade tip clearance zone that has a plurality of expansion cavitys to consist of.In addition, by using the blade tip clearance leakage flow coefficient of performance φ of ideal flow state _aWith entrance, discharge state, also can use formula (3) to calculate the leakage rate G in the blade tip clearance zone of perfect condition _I

$G_i={\mathrm{\α}}_i{F}_i{P}_{i-1}\sqrt{\frac{2{\mathrm{\κ}}_{i-1}}{{\mathrm{\κ}}_{i-1}-1}\frac{1}{{\mathrm{RT}}_{i-1}}\{{\left(\frac{P_i}{P_{i-1}}\right)}^{\frac{2}{{\mathrm{\κ}}_{i-1}}}-{\left(\frac{P_i}{P_{i-1}}\right)}^{\frac{{\mathrm{\κ}}_{i-1}+1}{{\mathrm{\κ}}_{i-1}}}\}},---\left(1\right)$

Will

In the substitution following formula:

$G_I={\mathrm{\&alpha;}}_i{\mathrm{<figure-callout\; id="2"\; label="F\; i"\; filenames="HDA00002526848000011.png,HDA00002526848000023.png"\; state="\{\{state\}\}">F</figure-callout>}}_i\sqrt{\frac{2{\mathrm{\&kappa;}}_{i-1}}{{\mathrm{\&kappa;}}_{i-1}-1}\{{\left(\frac{P_i}{P_{i-1}}\right)}^{\frac{2}{{\mathrm{\&kappa;}}_{i-1}}}-{\left(\frac{P_i}{P_{i-1}}\right)}^{\frac{{\mathrm{\&kappa;}}_{i-1}+1}{{\mathrm{\&kappa;}}_i}}\}\frac{P_{i-1}}{{\mathrm{\&nu;}}_{i-1}}},---\left(2\right)$

$G_I=\mathrm{\&alpha;F}{\mathrm{\&phi;}}_a\sqrt{\frac{P_U}{{\mathrm{\&nu;}}_U}},---\left(3\right)$

${\mathrm{\&phi;}}_a=\frac{\sqrt{1-{\mathrm{\&lambda;}}^2}}{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002526848000011.png,HDA00002526848000023.png"\; state="\{\{state\}\}">n</figure-callout>}}^{2/5}},---\left(4\right)$

In the Practical Project, when air-flow was regional by blade tip clearance, air-flow did not have abundant expansion of slowing down fully in the expansion chamber of separating fin formation, but some air-flow is from the inlet to the outlet shown in the straight line shape flow at high speed (such as Fig. 8).Under the impact that this phenomenon exists, the actual leakage rate G by the blade tip clearance zone of air-flow _EWith the leakage rate G that passes through the blade tip clearance zone under the perfect condition _IInevitable different, then represent under actual leakage rate by the blade tip clearance zone and the perfect condition ratio by the leakage rate in blade tip clearance zone, υ=G by dimensionless factor υ _E/ G _I, try to achieve large I simultaneous formula (5) and (6) of coefficient value υ, in the formula size and Orientation of θ with reference to shown in Figure 8,

$\mathrm{\&upsi;}=\sqrt{\frac{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="HDA00002526848000011.png"\; state="\{\{state\}\}">n</figure-callout>}}{1+(n-1){(1-A)}^2}},---\left(5\right)$

$A=\frac{\mathrm{\&epsiv;\&alpha;}/l}{(\mathrm{\&epsiv;\&alpha;}/l)+\tan \mathrm{\&theta;}},---\left(6\right)$

Therefore, express with formula (7) from the leakage rate that experiment obtains, namely multiply by formula (3) with coefficient value υ and obtain; In like manner, with a dimensionless factor Φ, namely the blade tip clearance leakage flow coefficient of performance comes the size of theoretical calculation leakage rate, and formula (8) is set up; If use the leakage rate G that obtains from experiment _EExpress blade tip clearance leakage flow coefficient of performance Φ, then formula (9) is set up; Be that formula (8) is the theoretical value that can characterize blade tip clearance leakage rate size, formula (9) is the experimental value that can characterize blade tip clearance leakage rate size,

$G_E=\mathrm{F\&upsi;\&alpha;}\sqrt{\frac{P_u}{{\mathrm{\&nu;}}_u}},---\left(7\right)$

Φ=υαφ _a， （8）

$\mathrm{\&Phi;}=G_E{\left(F\sqrt{\frac{P_u}{{\mathrm{\&nu;}}_u}}\right)}^{-1},---\left(9\right)$

φ _a: the blade tip clearance leakage rate function of approximate ideal;

λ: pressure ratio, namely

P _UThe entrance absolute pressure in blade tip clearance zone, P _DIt is the outlet absolute pressure in blade tip clearance zone;

N: separate the fin number;

θ: as shown in Figure 8, take at the top of separating fin as the angle of basic point Diffusion of gas stream, preferred 6 ° of θ;

α: flow coefficient, α=0.7;

F: air guide sleeve and the cross-sectional flow area of separating slit, fin place;

v _U: the gas specific volume of blade tip clearance area entry, i.e. the inverse of gas density,

Φ: blade tip clearance zone zero dimension performance parameter Φ.

Regulating static power is respectively 50Pa, 100Pa, 150Pa, 200Pa, 250Pa, under the guide ring state of rest, calculates the performance curve that obtains different blade tip clearances zone fluidal texture, as shown in Figure 9.Result of calculation shows: zero dimension performance parameter Φ in blade tip clearance zone changes with the number of the separation fin in the structure in blade tip clearance zone is different in the drawings, separates the situation that fin is counted n=2, and zero dimension performance parameter Φ is minimum, and namely leakage rate is minimum.The situation of n=5, zero dimension performance parameter Φ is maximum, and namely leakage rate is maximum.Simultaneously, along with pressure decreased, the blade tip clearance region performance is improved, and this is irrelevant with separation fin number.

Consider the cooling fan rotation motion to the impact of leakage rate, control guide ring rotating speed, the maximum rotating speed of cooling fan is about 2500rpm, i.e. the linear velocity U=47.4m/s of guide ring end.Same method regulating static power under the guide ring rotating speed 2500rpm state, is calculated the performance curve that obtains different blade tip clearances zone fluidal texture, as shown in figure 10 respectively at 50Pa, 100Pa, 150Pa, 200Pa, 250Pa.Result of calculation shows: under the guide ring rotating speed n=2500rpm state, the situation of n=3 and n=2 situation are in whole static pressure regulation range among the figure, and zero dimension performance parameter Φ is very approaching in the blade tip clearance zone, and namely leakage rate is more or less the same.But in the low pressure situation below the 100Pa, the zero dimension performance parameter Φ of n=2 increases, and is that leakage rate increases.The situation of n=5, zero dimension performance parameter Φ is maximum, and namely leakage rate is maximum.But when 50Pa, and the zero dimension performance parameter Φ of n=2 overlaps.As can be seen from Figure 10, and separate fin n=2, zero dimension performance parameter Φ compares under the guide ring state of rest, and under the turn state, the blade tip clearance region performance is largely increased in the total head scope, and namely zero dimension performance parameter Φ significantly reduces.

Reference

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Claims (6)

1. performance testing device with the automobile engine cooling fan blade tip clearance zone of guide ring, it is characterized in that: comprise air compartment test stand and accessory fan (14), atmosphere is led in the import of accessory fan (14), the outlet of accessory fan (14) and the entrance point UNICOM of air compartment test stand, be provided with tested device at air compartment test stand outlet end, atmosphere is led in the air outlet of tested device;

The inner chamber of described air compartment test stand is disposed with front current plate (15), nozzle (17) and rear current plate (16) along entrance point to the outlet end direction;

Described accessory fan (14) is connected with frequency variator (13), computing system (12) successively signal, computing system (12) is connected 11 with differential static pressure measuring device (18) with motor speed control device respectively in addition) signal is connected, and motor speed control device (11) is connected with motor (2) signal;

Described tested device comprises the guide ring (6) and seal disc (10) that is fixed together, and the periphery of guide ring (6) is equipped with air guide sleeve (4), and seal disc (10) is connected with the motor passback shaft drive of motor (2).

2. the performance testing device in the automobile engine cooling fan blade tip clearance zone with guide ring according to claim 1 is characterized in that: the internal-and external diameter allowance control of described air guide sleeve (4) and guide ring (6) is at ± 0.1mm.

3. the performance with the automobile engine cooling fan blade tip clearance zone of guide ring is determined method, it is characterized in that, utilizes claim 1 or 2 described tested device, specifically may further comprise the steps:

Under the standard operation state, namely external pressure is that a standard atmospheric pressure, ambient temperature are that 20 ℃, relative moisture are 50%, air density is 1.2kg/m ³Tested device is controlled under the constant rotating speed, come the rotating speed of regulating and controlling accessory fan (14) by frequency variator (13), regulate tested device import and outlet static pressure under the different flow, air stream is when nozzle (17), it is poor to have produced static pressure before and after nozzle (17), obtains static pressure difference value by differential static pressure measuring device (18);

The work static pressure of tested device is adjusted in 50Pa～250Pa scope carries out applied voltage test, simultaneously, the largest circumference speed of the guide ring (6) in tested device blade tip clearance zone is set to U=47.4m/s, one of the flow leakage rate group of dimensionless number certificate in prediction on such basis, thereby obtain the aeroperformance curve in tested device blade tip clearance zone.

4. performance according to claim 3 is determined method, it is characterized in that, the structure in described blade tip clearance zone comprises for straight-through U-groove bevel

Two structures of separating fin,

Or three structures of separating fin,

Or five structures of separating fin.

5. performance according to claim 3 is determined method, it is characterized in that, described work static pressure is set to respectively 50Pa, 100Pa, 150Pa, 200Pa, 250Pa, under the guide ring state of rest, obtains the performance curve of different blade tip clearances zone fluidal texture;

In addition, the work static pressure is set to respectively 50Pa, 100Pa, 150Pa, 200Pa, 250Pa, and the guide ring rotating speed is under the 2500rpm state, obtains the performance curve of different blade tip clearances zone fluidal texture.

6. performance according to claim 3 is determined method, it is characterized in that, described computational process is: the leakage rate in the blade tip clearance zone under the perfect condition is calculated with formula (1) or (2), the blade tip clearance zone subscripting i=1 that has a plurality of expansion cavitys to consist of, 2,3... many groups formula simultaneous solution, in addition, by using the blade tip clearance leakage flow coefficient of performance φ of ideal flow state _aWith entrance, discharge state, also use formula (3) to calculate the leakage rate G in the blade tip clearance zone of perfect condition _I,

$G_i={\mathrm{\&alpha;}}_i{F}_i{P}_{i-1}\sqrt{\frac{2{\mathrm{\&kappa;}}_{i-1}}{{\mathrm{\&kappa;}}_{i-1}-1}\frac{1}{{\mathrm{RT}}_{i-1}}\{{\left(\frac{P_i}{P_{i-1}}\right)}^{\frac{2}{{\mathrm{\&kappa;}}_{i-1}}}-{\left(\frac{P_i}{P_{i-1}}\right)}^{\frac{{\mathrm{\&kappa;}}_{i-1}+1}{{\mathrm{\&kappa;}}_{i-1}}}\}},---\left(1\right)$

Will In the substitution following formula:

$G_I={\mathrm{\&alpha;}}_i{F}_i\sqrt{\frac{2{\mathrm{\&kappa;}}_{i-1}}{{\mathrm{\&kappa;}}_{i-1}-1}\{{\left(\frac{P_i}{P_{i-1}}\right)}^{\frac{2}{{\mathrm{\&kappa;}}_{i-1}}}-{\left(\frac{P_i}{P_{i-1}}\right)}^{\frac{{\mathrm{\&kappa;}}_{i-1}+1}{{\mathrm{\&kappa;}}_i}}\}\frac{P_{i-1}}{{\mathrm{\&nu;}}_{i-1}}},---\left(2\right)$

$G_I=\mathrm{\&alpha;F}{\mathrm{\&phi;}}_a\sqrt{\frac{P_U}{{\mathrm{\&nu;}}_U}},---\left(3\right)$

${\mathrm{\&phi;}}_a=\frac{\sqrt{1-{\mathrm{\&lambda;}}^2}}{n^{2/5}},---\left(4\right)$

The actual leakage rate G by the blade tip clearance zone of air-flow _EWith the leakage rate G that passes through the blade tip clearance zone under the perfect condition _IInevitable different, then represent under actual leakage rate by the blade tip clearance zone and the perfect condition ratio by the leakage rate in blade tip clearance zone, υ=G by dimensionless factor υ _E/ G _I, the size of coefficient value υ is tried to achieve by simultaneous formula (5) and (6),

$\mathrm{\&upsi;}=\sqrt{\frac{n}{1+(n-1){(1-A)}^2}},---\left(5\right)$

$A=\frac{\mathrm{\&epsiv;\&alpha;}/l}{(\mathrm{\&epsiv;\&alpha;}/l)+\tan \mathrm{\&theta;}},---\left(6\right)$

Therefore, express with formula (7) from the leakage rate that experiment obtains, namely multiply by formula (3) with coefficient value υ and obtain; In like manner, with a dimensionless factor Φ, namely the blade tip clearance leakage flow coefficient of performance comes the size of theoretical calculation leakage rate, and formula (8) is set up; If use the leakage rate G that obtains from experiment _EExpress blade tip clearance leakage flow coefficient of performance Φ, then formula (9) is set up; Be that formula (8) is the theoretical value that can characterize blade tip clearance leakage rate size, formula (9) is the experimental value that can characterize blade tip clearance leakage rate size,

$G_E=\mathrm{F\&upsi;\&alpha;}\sqrt{\frac{P_u}{{\mathrm{\&nu;}}_u}},---\left(7\right)$

Φ=υαφ _a， （8）

$\mathrm{\&Phi;}=G_E{\left(F\sqrt{\frac{P_u}{{\mathrm{\&nu;}}_u}}\right)}^{-1},---\left(9\right)$

φ _a: the blade tip clearance leakage rate function of approximate ideal;

λ: pressure ratio, namely

P _UThe entrance absolute pressure in blade tip clearance zone, P _DIt is the outlet absolute pressure in blade tip clearance zone;

N: separate the fin number;

θ: take at the top of separating fin as the angle of basic point Diffusion of gas stream;

α: flow coefficient, α=0.7;

F: air guide sleeve and the cross-sectional flow area of separating slit, fin place;

v _U: the gas specific volume of blade tip clearance area entry, i.e. the inverse of gas density,

Φ: blade tip clearance zone zero dimension performance parameter Φ.

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