Flow Measuring Device Adaptive To Flow Field With Non-uniform Flow Velocity Distribution

In the actual pipeline installation at the industrial site,the design of the pipeline system is often limited by the space of the site.Pipeline bending,contracting and expansion often occur along the pipeline direction,together with the use of various pipe fittings,resulting in disordered flow field,Non-uniform velocity distribution,with vortex or secondary flow in the pipeline,which cause inaccurate measurement results and poor dynamic characteristics of flow meters.At present,the air supply ducts and flue pipes contain a large amount of dust in the most domestic coal-fired power plants.It is easy to plug the pressure measurement holes on the traditional air flow measuring devices in the dusty airflow,and the blockage problem of measuring primary elements has not been well solved.In this paper,the numerical simulation of fluid flow in a rectangular cross section right-angle bent was carried out by CFD numerical simulation software.The effects of the uniformity of flow field,local resistance and energy loss in the elbow were analyzed by using different number and structure of flow deflectors,and the optimal number and structure of deflectors were obtained.In addition,in order to solve the problem of blockage and wear resistance of air flow measuring devices in the dust-containing airflow,an air flow measuring device with high measurement accuracy,low pressure loss,anti-clogging and wear resistance was designed,and the high accuracy of the device were verified by theoretical and simulation experiments.This paper also proposes to verify the flow coefficient of the air flow measuring device by using numerical computation,which makes up for the limitation of flow coefficient calibration of flow meters in wind tunnel,laboratory and field,and provides a new method and technology for flow coefficient calibration of large diameter pipeline flow meters.