基于喷嘴挡板阀激励的航空燃油流量计动态校准技术基础问题研究

As one of the major parameters of fuel system in aero-engine tests, fuel flowrate is basically measured by turbine flowmeters. However, the meter coefficient would inevitably change due to the action of working medium, ambient condition or component wear. Because no dynamic calibration equipment and no corresponding appraisal procedure are applicable currently to these flowmeters used for a long time, confidence level for its dynamic measurement results is greatly affected and the practical demands for dynamic tests of high-maneuver aircrafts cannot be satisfied. This problem can be attributed to insufficient knowledge of the excitation flow generating mechanism and the way to get the dynamic meter coefficient..This project proposes the principle of a flowmeter dynamic calibration system using a nozzle-flapper valve for excitation flow. Through mathematical modelling, CFD numerical calculation, multibody system dynamics simulation and experiments, process of pipeline flowrate excitation induced by pressure difference jump of the series liquid resistance used is researched as well as flow mechanism and flow coefficients of the valve. And multibody system dynamics mapping between the driving signal of the exciting element and the excitated flowrate is also investigated to make sure the effective excitation range across the full flapper displacement zone. Real-time description of element state parameters and their data-driven transmission relations are studied by combining the experimental results with the system dynamics mapping, and real-time value of the element state parameters is filtered and corrected to calculate the current dynamic meter coefficient of the calibrated flowmeter for its performance evaluation of dynamic measurement. The project implementation can provide dynamic calibration of the flowmeters employed in varieties of low-viscosity liquid hydraulic systems with valuable references.

供油量是航空发动机燃油系统实验的主要参数之一，多选用涡轮流量计测量。受介质、环境与磨损等影响，其仪表系数必然变化。因缺乏动态校准设备和评估方法，极大影响了动态流量测量的置信度，无法满足大机动飞行器各类动态实验的实际需求。究其原因主要是对动态校准必需的激励流产生机理和流量计动态仪表系数获取方法尚不清楚。.本项目提出采用喷嘴挡板阀产生激励流的流量计动态校准原理，通过数学建模、CFD数值模拟、多体动力学仿真与实验手段，研究串联液阻压差突变的管路流量激励过程、喷嘴挡板阀的流动机理和流动参数；研究激励元件驱动输入对激励流多体动力学映射，据此分析全挡板位移区间的有效激励范围；结合实验和系统动力学映射研究元件状态量的时域描述及数据驱动的传递关系，筛选与修正状态量的时域值用于计算流量计当前的动态仪表系数，从而获得其动态测量性能评估方法。项目的实施对各类低粘度介质的液压系统流量计动态校准具有重要参考价值。

动态流量测量在高机动飞行控制、医疗等领域具有迫切的工程需求，流量计动态测试性能评估至关重要。本项目提出基于压电驱动燃油喷嘴挡板阀的短时变化流量激励原理，通过数学建模、CFD数值模拟等手段掌握了激励信号传递、激励油路内燃油流动机理，结合实验研究证实了根据串联液阻突变压差和激励流量分析被校流量计动态测量性能的可行性和有效性。. 通过分析激励油路流场，获得了激励系统驱动电压输入在供油压力影响下与控制腔压力及被试流量计前流速的映射关系，基本明确了有效激励范围；针对该原理的系统提出了激励油路数值模拟与流量计数学模型结合的流量计动态性能简易分析评价方法。通过对激励系统油路和被试流量计的联合建模与仿真，实现了动态校准系统元件状态量和流场参数(如输入电压、供油压力、挡板位移、控制腔压力、参考液阻前后压差、激励流量和读数流量等)的时域描述及重要参数对不同模型(部件)驱动运行的传递；基于涡轮流量计和齿轮流量计的校准系统仿真与实验结果，获得了修正系统响应延迟的被试流量动态性能指标即动态仪表系数和响应时间；计算流量计输出或读数值的传递函数即可获得独立于激励系统的动态特性，基于该方法获得某被试流量计的动态仪表系数为0.253 ml，且更易于获得。对压电叠堆驱动的喷嘴挡板阀产生激励流量的动态校准系统，先后研制了三套实验装置用三种不同流量计在多个典型工况下开展了几种设定流量和激励幅值的校准实验，验证了齿轮流量计与涡轮流量计、不同涡轮流量计动态性能的差异，获得了相关评价指标，并与理论结果对比，证实了本系统的效用。同时，将压电叠堆驱动的喷挡阀激励特性与力矩马达驱动方案进行了对比分析，也对两者在伺服阀中用作前置级的电液转换特性进行了分析，为今后压电驱动燃油伺服阀研制打下基础。