Lin Hua Piao

Study of the Gas Pendulum Characteristic of Enclosure with Small Size

The flow and temperature fields caused by point heat source were obtained with the method of FEA (finite element analysis), and the pendulum characteristic of nature convection gas in two-dimensional enclosure with small size was validated and explained. The results are as follow: (1) Whether in horizontal status or in tilting status, under the function of buoyancy lift, the direction of nature convection gas always keeps vertical upwards in two-dimensional enclosure, and it has the pendulum characteristic.(2)The temperatures of two points on the same isotherm are no longer equal. When the tilt angle is 10°, the temperature difference is 20K; when the tilt angle is 20°, the temperature difference is 40K.The tilt angle can be measured by using this characteristic of MEMS airflow level posture sensor.

Research of Two-Dimensional Airflow Angular Velocity Sensor

Proposed a two-dimensional air-angular velocity sensor. Dual vertical heat resistance wire, two-dimensional angular velocity sensitive; By simply supported edge piezoelectric pump support to improve the sensitivity of the sensor; Using stacked sheet round table groove type nozzle, improved stability and repeatability of the sensor; Using software compensation processing to improve the temperature performance and linearity of the sensor. Experimental results show that the sensitivity of the sensor improve nearly double, Zero variation decrease from≤10% to≤0.2%, operating temperature extended from-10°C~+40°C to-45°C~+65°C, linearity decrease from≤1% to ≤0.5%, the amount of sensitivity decrease from ≤10% to≤0.6%.

Research on Structure of the Airflow Level Posture Sensor

In this paper, three wire structure of the airflow level posture sensor is described. Using ANSYS-FLOTRAN CFD program, the temperature field and the stream field in sensing element of three wire structure and two wire structure under the effect of the different tilt state, has been obtained by a series of procedure, such as model building, meshing, loads applying and equation solving. The results are as follow: In tilt status, the airflow rate difference of three wire structure is nearly five times bigger than two wire structure in the two heat sources. Three wire structure makes heating wire separated from detection wire, solves the contradiction between operating current and output sensitivity, and decrease operating current. The test results show: The compare between three wire structure of the airflow level posture sensor and two wire structure of the airflow level posture sensor is that the sensitivity increases from 10 mV /° to 18mV/°,response time decreases from 100mS to 40mS,operating current decreases from 80mA to 40mA, so three wire structure is better than two wire structure.

Research of Airflow Level Posture Sensor Wire Thermal Structure

In order to compare and research the performance of airflow level posture sensor two wire structure and three-wire structure. By using FLUENT-CFD software, through modeling, meshing, solving and other methods, Respectively, the airflow level posture sensor of two-wire structure and three-wire structure are simulated in the sensitive of the velocity field of different tilt angles and different heat source temperatures. The results showed that the tilt sensitivity to changes of velocity of three-wire structure airflow level posture sensor is 0.3831·10-3m/s/0, and the two-wire structure is 0.2487·10-3 m/s/0, and the measurement range of three-wire structure airflow level posture sensor is 00 to 300, the two-wire structure is 00 to 200. The rate of change of three-wire structure airflow level posture sensor’s sensitive internal velocity difference change with the hot source temperature is 1·10-5m/s/0C, and the two-wire is 3.5·10-5m/s/0C. The performance of three-wire structure airflow level posture sensor in inclination and temperature is better than the two-wire structure’s.

Research of Micro Airstream Gyroscope Sensitive Mechanism

The sensitive mechanism of micro airstream gyroscope was explained by calculating the distributing of stream field in the sense organ. According to the real size of micro airstream gyro-scope, ANSYS-FLOTRAN CFD was used to create models and work out the gas flow field and distributing in the two-dimensional chamber with different angular velocities. The results show that while the gyroscope in a static state the gas velocities at both hot-wires are equal as well as the current, and the output voltage is zero. On inputting an angular rate the gas velocities differ and a voltage signal proportional to the input angular rate is achieved.

Modeling and Simulation of Airflow Level Posture Sensor

Modeling technology and simulation for micro-mechanical gas-flow level-gesture sensor is explained. Through ANSYS-FLOTRAN CFD program and by means of a series of procedures, such as 3d-modeling, network modifying, loads applying and equation solving, FEM analysis has been obtained. In order to analyze more conveniently and feasibly, By setting up several rational mechanics model schemes and using the method of cutting partial volume modeling, it has saved the massive time and the energy; The skills such as meshed times without number and the key-line meshed in even advanced the veracity and the calculation progress of simulation results.3d-modeling provides a more effective road for optimization of gas-flow level-gesture sensor.

Modeling and Simulation of Airflow Omnibearing Posture Sensor

In order to improve the performance of sensor, Using ANSYS software, the three-dimensional finite element modelling method and simulation results of micromachined airflow omnibearing level posture sensor are presented. The results show that: (1)Using the sense organ’s symmetry characteristic, a half model is built first, which is convenient for modelling and observing the simulation results;(2) Gridding should be meshed more densely where fluid grads is large, which is helpful of saving simulation time and improving precision. Compared to two-dimensional modeling, the simulation results of three-dimensional modeling are more comprehensive and exact, which provides dependable basis for further research of the sensor.

Study on Fluidic Gyroscope Zero Temperature Compensation Method

This paper had studied on the zero temperature compensation of fluidic gyroscope based on MEMS thermistor. Through the analysis of temperature characteristics of jet gyro sensitive element, two methods of comparison of zero temperature compensation was compared. Then, introduction of SCM and temperature sensor, to achieve zero temperature compensation for gyro output signal. The experiment shows: after compensation, zero voltage variation gyro reduced from 150mV to 10mV, working temperature range from room temperature to-40°C ~+55 °C. The fluidic gyroscope zero temperature compensated with zero drift is low, wide working temperature range advantages.

Study on a Craft Simulation Technology for the MEMS Thermal Element

On the basis of the craft manufacturing and designing about micro fluidic gyroscope, according to analyze the craft information and studying on the process simulation technology about the MEMS thermal components. Established a basic model of t the craft structure about the MEMS thermal components, based on this model, the L-Edit editor to edit creating a complete mask layout structure; studying a simulation method of craft process, the use of the technological editor which development based on the TCL/TK language to draw out the craft process document, then reconstructed the layout structure based the craft process in a 3D platform. It could be used to detect the rationality of the process program technology.

Finite Element Analysis of Flow Distribution on Nozzle Array Fluidic Gyroscope Performance

In this paper, the flow distribution in sensitive element of nozzle array structure gyroscope is analyzed. Using ANSYS-FLOTRAN CFD software, the finite element simulation is conducted by a series of procedures, such as two-dimensional model building of fluidic gyroscope, mesh, load applying and equation solving. The two-dimensional airflow distributions of nozzle array structure and normal structure gyroscopes are calculated. The results show that the highest velocity of nozzle array structure fluidic gyroscope is 0.71455m/s at the outlet, which is 47.6% of the nozzle velocity, and velocity is increased by 19.5% than the normal nozzle structure. By using nozzle array structure which can reduce velocity of vortex in sensitive cavity, promote airflow movement, increase temperatures changes and improve the sensitivity of fluidic gyroscope.