| The aero-engine is known as the “heart” of the aircraft,determining the performance,reliability,and economical efficiency of the aircraft.It serves as a concentrated manifestation of the national industrial foundation,scientific and technological level,and national defense.Working under harsh conditions such as high speed,high temperature,high pressure and high load for a long period of time,the technical requirements of aero-engine are extremely high.While advanced measurement methods and devices are the key for the development of high-performance aero-engine,enabling precise measurement of key parameters in the extremely complex environment.As the core components of aero-engine,compressor and combustion chamber have a decisive impact on the engine’s performance,e.g.,the compressor power consumption accounts for about 2/3 of the output power of the turbine and its tip clearance leakage flow loss accounts for 20 % to 30 % of the total aerodynamic loss.With the support of the special project of "two machines",this study conducts research on the flow field in the millimeter scale complex flow channel of the compressor tip clearance,atomization performance on a centrifugal fuel slinger with axial fuel/air supply under high rotational speed and the total temperature distribution of the high enthalpy and high-speed gas flow in the combustion chamber.These studies provide essential testing means and crucial data support for optimizing the design of the compressor and combustion chamber of aero-engines.Firstly,aiming at the requirements of visualizing of flow field in the small curved space of the compressor blade tip clearance,an optical window with a distortion elimination surface was designed.Additionally,a tracer particle efficient loading method and an anti-fouling light source arrangement scheme were proposed.Subsequently,a visualization measurement system for blade tip clearance flow field based on PIV technology was constructed to visualize the flow field in complex flow channels with limited blade tip clearance,obtaining the velocity field,vorticity field and pressure distribution.The designed distortion elimination surface optical window has an imaging displacement error of less than 1 pixel,as verified by calibration board.For the proposed tracer particle loading method,the numerical simulation and experiment study demonstrate its high loading efficiency and weak flow field interference.The results reveal the uneven characteristics of velocity and pressure distribution in the tip clearance of an axial flow compressor.There is a high-speed region,aligned with main flow direction,as well as a low-speed transition region located at about 1/3 chord length.Additionally,the leakage flow occurs at the location of2/3 chord length.A low-speed zone forms at the rear edge of the blade,which is also the leakage vortex generation zone.Moreover,significant differences between the transient and time-mean flow fields are evident in this region.With an increase in rotational speed,the main flow velocity of the leakage flow increases,and the leakage flow direction deflects due to the downward movement of the low-pressure area at the tip of the blade.The obtained research results provide valuable insights for the subsequent development of efficient methods to control leakage flow.Secondly,for the multi-parameter atomization field measurement of the array micro-hole nozzle fuel slinger,an ultra-high speed(40,000 r/min)centrifugal spray atomization test system was designed and constructed.Based on PDA and pulsed digital holography,this system allowed for three-dimensional multi-parameter measurement of a centrifugal fuel slinger atomization field with axial fuel/air supply.The effects of oil flow,gas pressure,and rotational speed on SMD and velocity distribution of RP-3 jet kerosene atomization field were revealed.It is discovered that fuel flow and gas supply pressure had limited influence on the oil film thickness and We number at the nozzle hole under operating conditions,and the SMD at different heights from the nozzle showed minimal change.However,the We number increased as the rotational speed escalated from 12,000 r/min to 37,122 r/min.At the nozzle exit positions of Z=20 mm and 30 mm,the SMD decreased from 68.5 μm,69.72 μm to 42.3 μm and 46.87 μm,respectively.Regarding the oil fog velocity field,both horizontal and vertical velocity components are significantly larger,with values approximately one order of magnitude higher than the axial velocity.With the increase of the axial distance,the horizontal and vertical velocities decreased,while the axial velocity increased.The atomization cone angle decreased as the rotational speed increased,and the atomization cone angle increased after the axial gas supply,promoting a more uniform atomization field and preventing oil mist from hitting the walls at high rotational speeds.Through studying the atomization field characteristics of the fuel slinger,it is evident that the arrangement of axial oil/gas supply and multiple array micro-hole nozzles has a certain application prospect in the application of small and medium-sized turbine engines.Finally,to fulfill the demand of high enthalpy and high speed(2,200 K,400 m/s)gas flow total temperature measurement in aero-engine combustion chamber,a multi-point double-shielded small water-cooled total temperature measurement harrow was developed,featuring an innovative corundum-lined interlayer hysteresis chamber structure,achieving on-line measurement of temperature distribution in aero-engine combustion chamber under high-temperature and highpressure operation conditions.For the high enthalpy gas flow in the combustion chamber,the designed double shield structure reduces the influence of water cooling,increases the temperature of the inner corundum wall and reduces the radiation error.The distribution characteristics of temperature,pressure and velocity in the stagnation chamber were systematically studied.With an area ratio of inlet to exhaust of 3.1,the stagnation effect of gas flow is obvious and there is no low-speed zone in the stagnation chamber.Additionally,the thermocouple exhibits good response characteristics.The results show that the thermocouple response time of the total temperature harrow is about 500 ms,enabling better representation of the temperature distribution of the combustion chamber under the ignition,lift load and rated load of the aero-engine.The velocity error,thermal conductivity error and radiation error are 4.2 K,31.5 K and 91 K,respectively,and the total relative error is about 5.6 %.The average temperature measured by the total temperature rake is close to the total temperature calculated by the total pressure,with a deviation of less than2.4 %.This accuracy fulfills the requirements for industrial measurement.The development of the multi-point total temperature harrow provides solid and powerful support for the optimization design of engine combustion chamber. |
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