| As the important detecting element,temperature sensor is widely used in research,industry and agriculture,national defense fields etc.Platinum temperature sensor has large measuring range,good chemical stability,high precision measurement,and platinum is accepted as the best material to make thermal resistance currently.Platinum temperature sensor installed in the aircraft engine inlet is easily affected by external working environment and platinum resistance will change which influences measurement precision.Researching platinum temperature sensor under actual work condition has an important significance to determine the sensor failure mechanism,improve the measurement accuracy,protect the safety of flight.The article selects platinum wire temperature sensor as the research object.Establish finite element model through modeling software and simplify the modal according to the analysis on the basis of accuracy.Flow field around platinum wire is simulated by FLUENT software to Obtain fluid velocity,pressure and the characteristic of flow field.The flow field data under the limit state of flow velocity is passed to platinum wire structure through the plane of fluid-structure coupled and applied in the simplified modal as the load.The results show that the air velocity of platinum wire and ridge surface is small and the surface force of platinum wire is small.The air impact has less influence on the failure of platinum wire.The fluid velocity,pressure and the characteristic of flow field around platinum wire is obtained according to the results of simulation.The effect on platinum wire failure is simulated under sandstone of different diameter,different impact velocity and impact Angle by HyperMesh,LS-DYNA,LS-PREPOST software.The calculation results show that the failure of platinum wire is related to the diameter of sandstone,impact angle and impact velocity.When the Platinum temperature Sensor is impacted by sandstone,several adjacent platinum wires contact together,equivalent sectional area increases,the equivalent length decreases,and the resistance value of platinum decreases.When the Platinum temperature Sensor is impacted by sandstone,but several adjacent platinum wires do not contact together,equivalent sectional area decreases,and the resistance value of platinum increases.Platinum wire become failure when impact speed exceeds critical speed,the resistance value measured becomes infinite.The simulation results agree with the failure deformation results under actual work condition.Sandstone is the main factor causing failure of platinum temperature sensor.Above all,sandstone impact is the main factor causing failure of platinum temperature sensor and air impact has less effect on deformation failure of platinum wire.Platinum resistance decreases when adjacent platinum wire contact with each other.But resistance increases when the adjacent platinum wire cause deformation without contact.The resistance value measured becomes infinite when the platinum wire break. |
