Dynamic Characteristics of Separation Shock in an Unstarted Hypersonic Inlet Flow

A study on the RR-to-MR transition of shock wave reflections near the leading edge in hypersonic flows

“…More flow conditions are summarised in table 2. An algorithm program for schlieren image quantisation based on the grey level (see Xue, Wang & Cheng 2018) is employed to compute the separation shock angles, and experimental uncertainties are characterised by the standard deviation. The experimental uncertainties are contributed by various factors, e.g.…”

Theoretical study on regular reflection of shock wave–boundary layer interactions

“…Additionally, although the separation points experience different positions, the influence of thickness change of boundary layer on SWBLI is small enough to be neglected, according to Grossman & Bruce (2018). An algorithm program for schlieren image quantization based on grey level (see Xue, Wang & Cheng 2018) is employed to detect the shock angles, by which the time history lines of incident shock angle on region A, separation shock angle close to interaction point on region B and separation shock angle close to boundary layer on region C were detected and illustrated in figure 11(). In the following sections, the average value () of angles is used for interaction analyses on shock polar lines, and the error bars are characterized by standard deviation ( STDEV ) such that and .…”

Correlation Analysis of Separation Shock Oscillation and Wall Pressure Fluctuation in Unstarted Hypersonic Inlet Flow

“…To detect the accuracy, a function to dye the localization is added to the C++ code and once the program runs, the separation shock boundary is marked; thus, the validity of quantization results can be observed directly. The number of the Schlieren images, which are dyed with the wrong boundary, is less than 0.1% [25]. To thoroughly research flow characteristics in time and frequency, and address the strong periodicity of the shock oscillation, WT (Wavelet Transform) analysis was adopted and produced the power spectral density (PSD) contours in Figure 10.…”

“…To detect the accuracy, a function to dye the localization is added to the C++ code and once the program runs, the separation shock boundary is marked; thus, the validity of quantization results can be observed directly. The number of the Schlieren images, which are dyed with the wrong boundary, is less than 0.1% [25]. Figure 11 shows the pressure time history of T1 to T5 (Figure 2) during t = 3.7-4.3 s. T1 first senses the back pressure, and the others lag behind in turn when the shock train moves upstream.…”

“…The test model is a Busemann-type [24] hypersonic inlet [25] (Figure 2) that is 980 mm in length with a rectangular exit, which is 40 mm in height and 44 mm in width. The inlet unstart state is generated by a throttling device with a plug (half-apex angle of 20 • ) driven by a stepper motor.…”