AIAA Scitech 2021 Forum最新文献_第2页

Virtual Experiments of Light and Shock Wave Interaction Using Nonlinear Ray Tracing and Photon Mapping 基于非线性光线追踪和光子映射的光与激波相互作用虚拟实验

AIAA Scitech 2021 Forum Pub Date : 2021-01-04 DOI: 10.2514/6.2021-1483

Frederico Dias Paulino da Costa, A. Gaitonde, Dorian P. Jones

{"title":"Virtual Experiments of Light and Shock Wave Interaction Using Nonlinear Ray Tracing and Photon Mapping","authors":"Frederico Dias Paulino da Costa, A. Gaitonde, Dorian P. Jones","doi":"10.2514/6.2021-1483","DOIUrl":"https://doi.org/10.2514/6.2021-1483","url":null,"abstract":"Light impinging on an aircraft wing surface interacts with the shock waves that form around it due to the high-speed ﬂow and produces an oscillatory optical phenomenon composed of image distortions or shadow patterns, visible from the airborne perspective under particular observer, vehicle operation and illumination conditions. Analogously to traditional experimental techniques of shock wave visualization, the phenomenon can in principle be replicated computationally in its entirety, although the exact conditions that make it visible are still unknown. From a virtual experiment, it remains to be established what can be inferred about the shock wave and the trans-super sonic ﬂow itself from the observed visual artifacts. This paper develops a three-dimensional nonlinear ray equation solver to predict the light propagation from the sun, through the refractive inhomogeneous density ﬁeld acquired from a two-dimensional computational ﬂuid dynamics (CFD) simulation and assembled as a pseudo-three-dimensional ﬂow domain, to the physically-based reﬂective wing surface. Employing the traditional linear ray tracing algorithm, the photon mapping rendering technique and a simpliﬁed viewing system implementation, this computational tool is then used to assess the differences in the scene illumination caused by the shock wave. The contrast between the reﬂected radiance values, represented as a color triplet in the RGB space, considering the aerodynamic inhomogeneous ﬂow ﬁeld and a ﬁctitious homogeneous optical medium demonstrates that the shock wave indeed induces radiometric disturbances. A strategically positioned and oriented recording ﬁlm is able to capture magniﬁed deﬂections of light rays and samples of the density of photons result in the reproduction of the shock wave’s shadow formation. Visualized as in the shadowgraphy experiment or observed from a perspective around the aircraft wing, the characteristics of the shadow pattern depend on the number of photons and the direction that they are emitted from the light source.","PeriodicalId":165313,"journal":{"name":"AIAA Scitech 2021 Forum","volume":"236 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132069706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}