摘要
PSP is an advanced measurement technique that uses fluorescence intensity changes to capture global surface pressure distributions without altering surface characteristics. Due to its high sensitivity, PSP can provide detailed pressure informaiton on the model surface. The pressure contours obtained by PSP masurements can reveal the intersting phenomena on complex flow fields. Egami et al. [1] demonstrated that Ru(dpp) ₃-based sprayable PC-PSP with RTV-118 polymer and mesostructured silica particles achieved a rapid response (5 µs), high pressure sensitivity, and low temperature sensitivity, suitable for complex three-dimensional models. Chen et al.[2] demonstrated that PSP effectively captures detailed two-dimensional pressure distributions and visualizes complex flow features with high spatial resolution. Their results indicated that VGs significantly shortened recirculation zones and improved downstream pressure recovery under transonic flow conditions. Kim et al. [3] investigated incompressible backward-facing step (BFS) flow. They highlighted peak turbulence intensity and shear stress at reattachment, followed by recovery to a normal turbulent boundary layer. This study investigates the effects of CRV type VGs on flow characteristics around a BFS model PSP measurements. Experiments were conducted in a transonic wind tunnel at a Mach number of 0.8, corresponding to a Reynolds number of 2.19 × 10⁷/m. The PSP formulation used Ru(dpp) as the luminescent molecule embedded in an RTV 118 polymer binder with toluene as the solvent, exhibiting a pressure sensitivity of 0.7% per kPa. Experiments were performed under controlled lighting conditions to ensure accurate and reliable surface pressure measurements.Figure 1 illustrates typical pressure distribution characteristics over the BFS region. Initially, flow separation occurs immediately downstream of the step, forming a low-pressure region indicated in blue.As the flow moves downstream, pressure gradually recovers, transitioning from blue through green and yellow to red, ultimately stabilizing after reattachment. This behavior demonstrates standard BFS flow phenomena, including separation, pressure recovery, and eventual stabilization into a steady boundary layer state. In this study, PSP experiments were conducted to measure the pressure distribution over a BFS model equipped with CRV type VGs in a transonic wind tunnel at a Mach number of 0.8. VGs of three different heights were evaluated to analyze their effects on flow characteristics, particularly regarding reattachment length and flow accumulation. Centerline pressures were analyzed and validated with Kulite pressure transducers. Oil flow visualization was also employed for qualitative verification and was found to be consistent with PSP results, confirming the reliability of PSP measurements. Compared with oil flow visualization, PSP provided more detailed, comprehensive two-dimensional pressure distributions and effectively identified low-pressure regions associated with vortex structures induced by the vortex generators. References 1. Egami Y, Sato Y and Konishi S. Development of polymer/ceramic pressure-sensitive paint with the same response time as anodized-aluminum PSP.