# Response and Flow Characteristics of an Angular Momentum Flowmeter

## TL;DR

This paper studies how an angular momentum flowmeter works by simulating and analyzing its internal components under different flow conditions.

## Contribution

The study introduces a visualization platform and angular momentum algorithm to analyze flowmeter dynamics and improve measurement accuracy.

## Key findings

- The flow process is divided into three regimes based on spring response states.
- At 0.091 kg/s flow rate, the upstream rotor rotates stably at 1.1 rad/s.
- Flat spring configuration improves stability by dissipating secondary vortices.

## Abstract

The angular momentum flowmeter addresses critical challenges in aviation fuel flow measurement during commercial flight operations. This study designed a visualization platform to observe the dynamic responses of internal components under varying flow conditions. By employing the sliding mesh method coupled with an angular momentum algorithm, it enabled the dynamic rotation simulation of the upstream straight-bladed rotor and provided calculation of the deflection angle in the downstream straight-bladed rotor of an angular momentum flowmeter. Experimental results categorize the flow process into three distinct regimes based on flat and spiral spring response states: pre-spring, single-spring, and dual-spring regimes. Under a flow condition of 0.091 kg/s, the upstream straight-bladed rotor maintained stable rotation at a speed of 1.1 rad/s. At a flow rate of 0.20 kg/s, the flat spring initiated outward expansion, and with further increase in flow rate, the rotational speed of the upstream straight-bladed rotor remained within the range of 25.34–26.21 rad/s. Mathematical analysis demonstrates that the flat spring configuration extends the lower measurement limit and promotes dissipation of the secondary vortex through dominant kinetic energy of the primary vortex during dual-spring operation, thereby improving high-pressure zone stability. This work elucidates the operational mechanism of angular momentum flowmeters and provides a theoretical basis for structural optimization.