High-Volume Low-Turbulence Inlet for Aerosol Sampling from Aircraft

在这个项目中，将设计、建造一个用于NCAR C-130飞机的大容量低湍流气溶胶入口，并对其性能进行验证。这个入口将使采样的超微米气溶胶高达10微米的空气动力学直径。需要一个低湍流的入口，以尽量减少颗粒对入口壁面的损失。入口扩压段的边界层吸力将被用作湍流缓解技术。提议的入口将有200-400升每分钟的流量，以提供一个大容量的级联冲击系统。由于目标流速高于许多其他要求，该项目也将使设计类似的入口用于其他更一般的气溶胶采样应用成为可能。将建立一个参考入口（没有边界层吸力），为评估湍流减少技术提供基线。它将使用传统设计的锥形扩散器来产生20倍的速度降低（扩散器入口速度与出口速度的比率）。参考进气道将在一系列与C-130飞机的飞行包线相对应的条件下进行测试，以确定扩散器出口的流动特性（时间平均速度和湍流强度）。一个低湍流进气道（利用边界层吸力）将作为在先前国家科学基金项目中成功演示的进气道的放大版本而建造。扩散器部分将由铸造和烧结多孔塑料制成。大约60-80%的进口气流将通过吸力去除，以实现所需的速度降低20倍。第二年，将在实验室对低湍流度进气道进行表征和优化。C-130飞机的飞行系统将被设计和建造。通过对扩压器出口流动特性的测量和扩压器壁内及壁外流动的计算流体动力学分析相结合，将确定入口内的流动应力线和大颗粒的惯性增强。惯性增强也将通过实验来确定，在几个选定的测试条件下，在运行期间使用光学粒子计数器或气动粒子大小计测量入口外和扩散器出口的粒子大小分布。第三年的目标是进气道的飞行测试和进气道系统用户的操作协助。

9713408 Seebaugh In this project, a high-volume low-turbulence aerosol inlet for use on the NCAR C-130 aircraft will be designed, constructed, and its performance demonstrated. This inlet will enable the sampling of supermicron aerosols up to 10 micrometer aerodynamic diameter. A low turbulence inlet is required to minimize particle losses to the inlet walls. Boundary layer suction in the diffuser section of the inlet will be used as the turbulence mitigation technique. The proposed inlet will have a flow rate of 200-400 liters per minute to supply a high-volume cascade impactor system. This project will also make it possible to design similar inlets for other more general aerosol sampling applications since the target flow rate is higher than many other requirements. A reference inlet (without boundary layer suction) will be built to provide a baseline for evaluation of the turbulence reduction techniques. It will use a conical diffuser of conventional design to produce a velocity reduction (ratio of diffuser entrance to exit velocity) of a factor of 20. The reference inlet will be tested over a range of conditions corresponding to the flight envelope of the C-130 aircraft to determine the flow characteristics (time mean velocity and turbulence intensity) at the diffuser exit. A low turbulence inlet (using boundary layer suction) will be built as an enlarged version of the inlet successfully demonstrated during prior NSF project. The diffuser section will be manufactured from a cast and sintered porous plastic. About 60-80% of the inlet flow will be removed by suction to achieve the desired velocity reduction of a factor of 20. In the second year, the low turbulence inlet will be characterized and optimized in the laboratory. A flight system for the C-130 aircraft will be designed and constructed. By combining measurements of the flow characteristics at the diffuser exit and computational fluid dynamics analysis of the flow within and through the walls of the diffuser, the flow stre amlines inside the inlet and the inertial enhancement for large particles will be determined. The inertial enhancement will also be determined experimentally by measuring the size distribution of particles outside the inlet and at the diffuser exit during operation using either an optical particle counter or an aerodynamic particle sizer for several selected test conditions. The objectives of the third year effort are flight testing of the inlet and operational assistance for users of the inlet system.