Extension of frequency modulated Doppler global velocimetry for the investigation of unsteady spray flows
Extension of frequency modulated Doppler global velocimetry for the investigation of unsteady spray flows
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DOI：
10.1016/j.optlaseng.2014.06.002
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发表时间：
2014-12
影响因子：
4.6
通讯作者：
A. Fischer;U. Wilke;Raimund Schlüßler;D. Haufe;T. Sandner;J. Czarske
中科院分区：
文献类型：
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作者：
A. Fischer;U. Wilke;Raimund Schlüßler;D. Haufe;T. Sandner;J. Czarske
为了优化燃油喷射，需要具有低于一毫秒的高时间分辨率的测量技术来及时解析燃油喷雾速度场。由于测量速率通常太低而无法一次捕获单次注射的时间行为，因此在注射期间执行单次测量，并且以可变的测量时间延迟重复注射。因此，无法解决燃料喷雾的非平稳特性。为此，除了高时间分辨率之外，还需要≥ 1 kHz 的高测量速率。虽然时间分辨粒子成像测速 (PIV) 能够实现如此高的测量速率，但多普勒全局测速 (DGV) 要么太慢，要么仅限于速度剖面 (1d) 测量。然而，DGV 由于其高光学鲁棒性而被认为是 PIV 的有用替代或补充。因此，调频 DGV 得到增强，可提供速率≥ 1 kHz 的现场 (2d) 测量。这是通过使用微型扫描仪或应用高速相机来实现的。两种设置都提供了喷雾测试对象中的时间分辨速度场测量，而无需重复喷雾循环。在每次运行期间，都识别出相同的特征振荡，并且解决了喷雾喷射结束时速度的降低。因此，该技术适用于分析瞬态、非稳态喷雾现象。
For the optimization of fuel injection, measurement techniques with a high temporal resolution below one millisecond are required to resolve the fuel spray velocity field in time. Since the measurement rate is usually too low to capture the temporal behavior of a single injection at once, a single measurement is performed during the injection and the injection is repeated with a variable time delay of the measurement. Consequently, non-stationary characteristics of the fuel spray cannot be resolved. For this purpose, a high measurement rate≥ 1 kHz is necessary in addition to the high temporal resolution. While time-resolved particle imaging velocimetry (PIV) is capable of achieving such high measurement rates, Doppler global velocimetry (DGV) is either too slow or is restricted to velocity profile (1d) measurements. However, DGV is considered to be a useful alternative or complement to PIV due to its high optical robustness. For this reason, the frequency modulated DGV is enhanced to provide field (2d) measurements with rates of≥ 1 kHz. This is achieved either by using a micro scanner or by applying a high-speed camera. Both setups provided time-resolved velocity field measurements in a spray test object without repetition of the spray cycle. During each single run, the same characteristic oscillations were identified and the decrease of the velocity at the ending of the spray injection was resolved. Hence, the technique is applicable for analyzing transient, non-stationary spray phenomena.