A flow measurement system consisting of an optical fiber Fabry–Perot (F-P) sensor and an elbow tube is proposed and demonstrated to realize flow measurements and eliminate thermal disturbance. Two F-P sensors are symmetrically mounted on the inner-wall surface of the elbow of 90° in order to eliminate the effect of thermal disturbance to the flow measurement accuracy. Experimental results show that the absolute phase difference is the square root of the fluid flow. It is consistent with the theo
