Polymer-Based Micro Flow Sensor with Alternative Electronic Signal Interfaces for Low and High Flow Rates

The qualitative and quantitative assessment of gas flow has become increasingly relevant in the use of everyday systems. The micro flow sensor, developed by Innovative Sensor Technology AG （Switzerland）, is by principle a calorimetric flow sensor produced as a micro system on a glass substrate by means of photolithography and glass etching technology. These structures are arranged as a platinum micro heater and sensor in a Wheatstone bridge. The subsequent etching process produces an exposed area of polyimide membrane that is only a few microns thick and includes the resistive sensor structure as the active area. In addition, the RTD （resistance temperature detector） technology included on the sensor allows for the implementation of a variety of electronic biasing and signal processing modes. Since the sensor can be powered and the bridge can be measured in both CTA （constant temperature anemometer） and calorimetric mode, new possibilities are presented for both low and high flow rates with regard to temperature compensation, self-calibration and self-monitoring.

Investigation and numerical simulation of inner-flow of an axial mineflow fan under low flow rate conditions

Because of unstable properties of axial mine flow fans working under conditions of low flow rates, the safety and reliability of fans in their operational zone is reduced. At times, serious vibration may bring about the destruction of equipment or even jeopardize the safety of entire factories. By means of oil flow visualization techniques and numerical simulation, we have investigated the inner-flow of an axial mine flow fan working under low flow rate conditions. The fundamental reasons of complex flow phenomena of the inner-flow of the flow fan under these stated conditions were revealed. At the same time and in order to improve the inner-flow under conditions of low flow rates, a blade separator and air separator were designed. From our tests we found that the blade separator and air separator are two kinds efficient methods to improve the unstable working characteristics of the axial mine flow fan operating under low flow rate conditions. The effect of the improvement of the air separator is stronger than that of the blade separator.

Methodology for production logging in oil-in-water flows under low flow rate and high water-cut conditions

This study aimed to obtain the production profiles of oil-in-water flow under low flow rate and high water-cut conditions in oil wells.A combination production profile logging composed of an arc-type conductance sensor(ATCS)and a cross-correlation flow meter(CFM)with a center body is proposed and experimentally evaluated.The ATCS is designed for water holdup measurement,whereas the CFM with a center body is proposed to obtain the mixture velocity.Then,a drift-flux model based on flow patterns is established to predict the individual-phase superficial velocity of oil-in-water flows.Results show that the ATCS possesses high resolution in water holdup measurement and that flow pattern information can be deduced from its signal through nonlinear time series analysis.The CFM can enhance the correlation of upstream and downstream signals and simplify the relationship between the cross-correlation velocity and mixture velocity.On the basis of the drift-flux model,individual-phase superficial velocities can be predicted with high accuracy for different flow patterns.

A numerical simulation strategy for a compressor’s underlying axisymmetric characteristic and its application in body force model

Accurate prediction of the aerodynamic response of a compressor under inlet distortion is crucial for next-generation civil aircraft,such as Boundary Layer Ingestion(BLI)silent aircraft.Therefore,research on the Body Force(BF)model plays a significant role in achieving this objective.However,distorted inlet airflow can lead to varying operating conditions across different spatial locations of the compressor,which may cause some regions to operate outside the stability boundary.Consequently,the accuracy of BF model simulations might be compromised.To address this issue,this paper proposes a numerical simulation strategy for acquiring the steady axisymmetric three-dimensional flow field of a compressor operating at low mass flow rates,which is known as the Underlying Axisymmetric Pressure Rise Characteristic(UAPRC).The proposed simulation accounts for two different rotor speeds of a transonic compressor and identifies initial positions in the flow field where deterioration occurs based on prior experimental investigations.Moreover,simulation results are incorporated into the BF model to replicate hub instability observed in experiments.Obtained results demonstrate that this strategy provides valid predictions of the UAPRC of the compressor,thereby addressing the limitations associated with the BF model.