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CN-121997664-A - Dynamic blade tip clearance control method and system for axial flow fan

CN121997664ACN 121997664 ACN121997664 ACN 121997664ACN-121997664-A

Abstract

The application provides a dynamic blade tip clearance control method of an axial flow fan, which comprises the following steps of S1, constructing a multi-physical field coupling analysis model of an impeller-frame system, S2, carrying out simulation calculation on the radial maximum displacement delta R_rotor of the impeller and the radial minimum displacement delta R_housing of the inner circle of the frame based on the multi-physical field coupling analysis model to obtain an impeller outer edge dynamic envelope range and a frame inner edge dynamic envelope range under a design working condition, S3, calculating the minimum safety clearance required between the impeller and the frame, and S4, guiding the mechanical design of the fan according to the calculated minimum safety clearance delta_min, and ensuring that the actual assembly blade tip clearance is more than or equal to delta_min. According to the method, the minimum safety clearance is accurately calculated, the fan is guided to be designed and manufactured, and the blade tip clearance is minimized and optimized on the premise of avoiding operation interference.

Inventors

  • LIU HUANHUAN
  • XU BING

Assignees

  • 吉诺凯博汽车科技(合肥)有限公司

Dates

Publication Date
20260508
Application Date
20260128

Claims (10)

  1. 1. The dynamic blade tip clearance control method for the axial flow fan is characterized by comprising the following steps of: The method comprises the following steps of S1, constructing a multi-physical field coupling analysis model of an impeller-frame system, wherein the model at least comprises a radial deformation model of an impeller under centrifugal force and temperature load, a static manufacturing tolerance model of the impeller and the frame, a coaxiality error model of an impeller supporting system and a dynamic deformation model of the frame under vibration and temperature load; S2, based on the multi-physical field coupling analysis model, simulating and calculating the maximum radial displacement delta R_rotor of the impeller and the minimum radial displacement delta R_housing of the inner circle of the frame to obtain the dynamic envelope range of the outer edge of the impeller and the dynamic envelope range of the inner edge of the frame under the design working condition; Step S3, calculating a minimum safety gap delta_min required between the impeller and the frame, wherein delta_min=delta R_rotor_max-delta R_housing_min+K×sigma_total, delta R_rotor_max is the maximum radial displacement of the outer edge of the impeller, delta R_housing_min is the minimum radial displacement of the inner circle of the frame, sigma_total is the total uncertainty of the system, and K is a safety coefficient; and S4, guiding the mechanical design of the fan according to the calculated minimum safety clearance delta_min, and ensuring that the actual assembly blade tip clearance is more than or equal to delta_min.
  2. 2. The method according to claim 1, wherein in step S1, the radial deformation model of the impeller under centrifugal force and temperature load specifically includes: And establishing a finite element model of the impeller, applying centrifugal force load and temperature field distribution load corresponding to the working condition rotating speed, and calculating the total radial displacement field after radial thermal expansion deformation and centrifugal deformation superposition of the impeller from a static cold state to a working state through thermal-structural coupling analysis.
  3. 3. The method for controlling the dynamic blade tip clearance of an axial flow fan according to claim 2, wherein the temperature field distribution load is obtained based on computational fluid dynamics analysis, taking into account the combined effect of the internal flow heat transfer of the fan and the external ambient temperature.
  4. 4. The axial flow fan dynamic tip clearance control method of claim 1, wherein in step S1, the static manufacturing tolerance model of the impeller and frame includes: an outer radial runout tolerance zone delta_rotor_ machining after impeller machining and an inner radial runout tolerance zone delta_housing_ machining after frame machining.
  5. 5. The axial flow fan dynamic blade tip clearance control method according to claim 1, wherein in step S1, the coaxiality error model of the impeller supporting system includes: And the dynamic coaxiality deviation delta_ concentricity of the impeller center and the frame center caused by bearing play, bearing seat machining errors and shafting deflection deformation.
  6. 6. The method according to claim 1, wherein in step S1, the dynamic deformation model of the frame under vibration and temperature load comprises: the frame is subjected to radial deformation of the inner circle of the frame caused by vibration excitation and temperature gradient of the fan operation, and the dynamic deformation delta_housing_displacement of the inner circle of the frame is estimated through modal analysis and random vibration analysis.
  7. 7. The method for controlling the dynamic tip clearance of an axial flow fan according to claim 1, wherein in step S2, the calculation formula of the impeller radial maximum displacement Δr_rotor_max is: ΔR_rotor_max = ΔR_centrifugal + ΔR_thermal_rotor + δ_rotor_machining/2 + δ_concentricity; Where ΔR_centrafugal is the maximum radial deformation of the impeller due to centrifugal force and ΔR_thermal_rotor is the maximum radial thermal expansion of the impeller due to temperature.
  8. 8. The method for controlling the dynamic tip clearance of an axial flow fan according to claim 1, wherein in step S2, the calculation formula of the radial minimum displacement Δr_housing of the inner circle of the frame is: ΔR_housing_min = ΔR_thermal_housing - δ_housing_machining/2 - δ_housing_vibration - δ_concentricity; where ΔR_thermal_housing is the minimum temperature induced radial thermal expansion of the inner circle of the frame.
  9. 9. The method according to claim 1, further comprising the step of arranging temperature and vibration sensors at the critical positions of the fan, monitoring temperature and vibration data of the impeller and the frame in real time, and dynamically correcting the minimum safety gap delta_min.
  10. 10. An axial flow fan wheel and frame gap design system, comprising: a multi-physics field coupling analysis module for performing the method steps S1-S3 of any one of claims 1-9; The clearance optimization design module optimizes structural design parameters of the impeller and the frame based on the minimum safety clearance delta_min obtained through calculation; and the real-time monitoring module is used for monitoring the running state of the fan in real time and dynamically evaluating the safety of the blade tip clearance.

Description

Dynamic blade tip clearance control method and system for axial flow fan Technical Field The application relates to the technical field of fluid machinery design and manufacture, in particular to a control method and a system for blade tip clearance of an axial flow fan, and particularly relates to a dynamic blade tip clearance accurate design method and a system based on multi-physical field coupling analysis. Background The performance and reliability of the axial flow fan serving as core equipment widely applied to the fields of ventilation, cooling, air conditioning and the like directly influence the system efficiency. Tip clearance (radial distance between the impeller blade tips and the inner wall of the fan frame) is one of the key design parameters of axial flow fans. Theoretically, smaller tip clearances can effectively reduce leakage losses, improve fan efficiency and output pressure, and reduce noise caused by tip vortex. However, too small a tip clearance may cause interference between the impeller and the frame during operation of the fan, and particularly under complex conditions such as high temperature, high speed, vibration, etc., the risk of such interference increases significantly. The traditional blade tip clearance design method mainly depends on an empirical formula and static analysis, is generally based on the geometric dimension in a normal-temperature static state, and is used for reserving a fixed clearance after simply considering machining tolerance. The method has obvious defects that 1) radial deformation caused by centrifugal force of the impeller during high-speed rotation is not fully considered, 2) dimensional change caused by thermal expansion of the impeller and frame materials at the working temperature is not considered, 3) dynamic deformation of the frame and the supporting system in a vibration environment is not evaluated systematically, and 4) the comprehensive influence of static deviation such as manufacturing tolerance, coaxiality error and the like is not quantized. In the prior art, some precise rotary machines (such as aeroengines) adopt an active clearance control technology, but the system has a complex structure and high cost, and is not suitable for common industrial fans. While most industrial fans still employ a conservative gap design, resulting in performance losses. Patent cn20231056789.X discloses an impeller gap design method that takes into account thermal deformation, but only a single factor of temperature. Patent CN20221123456.7 relates to a method for preventing fan impeller from collision and abrasion, mainly preventing interference by monitoring and alarming, belonging to the field of post-protection rather than pre-design optimization. Therefore, development of a precise design method for blade tip clearance comprehensively considering multiple physical field factors is needed, and on the premise of ensuring safety and reliability, minimization and optimization of the blade tip clearance are realized, so that the performance of a fan is improved. Disclosure of Invention The application aims to overcome the defects of the prior art and provide a method and a system for controlling the dynamic blade tip clearance of an axial flow fan, which are used for accurately calculating the minimum safety clearance by analyzing the dynamic deformation behaviors of an impeller and a frame under the coupling action of multiple physical fields such as centrifugal force, temperature, vibration, manufacturing tolerance and the like through the system, guiding the design and the manufacture of the fan and realizing the minimum optimization of the blade tip clearance on the premise of avoiding operation interference. The embodiment of the application provides a dynamic blade tip clearance control method of an axial flow fan, which comprises the following steps: The method comprises the following steps of S1, constructing a multi-physical field coupling analysis model of an impeller-frame system, wherein the model at least comprises a radial deformation model of an impeller under centrifugal force and temperature load, a static manufacturing tolerance model of the impeller and the frame, a coaxiality error model of an impeller supporting system and a dynamic deformation model of the frame under vibration and temperature load; S2, based on the multi-physical field coupling analysis model, simulating and calculating the maximum radial displacement delta R_rotor of the impeller and the minimum radial displacement delta R_housing of the inner circle of the frame to obtain the dynamic envelope range of the outer edge of the impeller and the dynamic envelope range of the inner edge of the frame under the design working condition; Step S3, calculating a minimum safety gap delta_min required between the impeller and the frame, wherein delta_min=delta R_rotor_max-delta R_housing_min+K×sigma_total, delta R_rotor_max is the maximum radial displacement of the outer edge