温度自补偿的偏心推杆式光纤光栅井下压力计

Eccentric-pushrod-based downhole FBG pressure sensor with temperature self-compensation

针对多数光纤光栅压力计不能兼顾大量程和高灵敏度,且温度无法实现自动补偿的问题,本文提出了一种偏心推杆结构,并采用将两支光纤光栅对称粘贴在应变杆上下表面的方法,设计并制作了光纤光栅井下压力计。对压力计传感头部分进行了理论分析和仿真,并对压力计进行了压力标定和温度实验。实验结果表明:此压力计具有良好的线性度和重复性,几乎没有弹性滞后,在0~30 MPa的大量程范围内灵敏度达到了230.8 pm/MPa,并且在20~80℃温度区间内,两光纤光栅中心波长差几乎不变,可见此压力计能够实现温度自动补偿。

Most fiber bragg grating pressure gauges cannot take account of large range,high sensitivity and temperature self compensation at the same time.Aiming at these problems,an eccentric pushrod structure was proposed,and two fiber bragg gratings were used to affix on the upper and lower surfaces of the pushrod symmetrically.Theoretical analysis and simulation were carried out on the structure of the sensor head of the pressure gauge.The pressure and temperature test were carried out.Experimental results show that this gauge possesses good linearity and repeatability,as well as little elastic hysteresis and temperature self compensation.The sensitivity of the gauge can reach2308pm/MPa when the measured pressure is in the range of0~30MPa.In the temperature range of20~80℃,the central wavelength difference of the two fiber bragg gratings is nearly constant,which shows a good temperature self compensation.