Shock tube

About: Shock tube is a research topic. Over the lifetime, 6963 publications have been published within this topic receiving 99372 citations.

Normal shock wave reflection on deformable solid walls

Abstract: A theoretical-experimental study has been performed on the interaction between normal shock waves and deformable solid materials, with particular reference to the characteristics of the reflected shock wave. The present study is of importance in all those cases in which a shock wave impings on solid walls (i. e. explosions, sonic booms etc.). The first part presents a theoretical analysis which gives the solution for the shock wave intensity reflected into the gas and for the transmitted shock wave propagating into the elastic solid material for both the cases of linear (Hooke type) and non linear solids. For the first kind of materials a closed form solution is found. For the non-linear materials the problem is solved through a numerical analysis. The experiments concern with two kinds of expanded foams (closed cell and open cell foams). These materials have been selected because of the good deformation and density characteristics which both are necessary to evidentiate the shock wave interaction phenomena. The tests have been performed putting a cylindrical model of the material under study at the closed end of a shock tube and creating shock waves of variable strength which impinge on the material. Slightly upstream of the free end wall of the model, the pressures history is recorded by means of a pressure pick up and of an oscilloscope. The range of the shock wave Mach number has been1,2⩽Ms⩽2,2 with initial pressures ranging between50⩽p 1 ⩽760 mmHg. The theoretical analysis seems to be in a very good agreement with the experiments performed, especially when due account is given to the gap existing between shock tube and model walls.

Two-color laser absorption near 5 μm for temperature and nitric oxide sensing in high-temperature gases

Abstract: An infrared laser-absorption technique for in situ temperature and nitric oxide species sensing in high-temperature gases is presented. A pair of quantum cascade lasers in the mid-infrared near 5 μm were utilized to probe rovibrational transitions in nitric oxide's fundamental band. The line parameters of the selected transitions, including line strengths and collision broadening coefficients of nitric oxide with argon and nitrogen, were evaluated during controlled room-temperature static cell experiments and high-temperature shock tube experiments at temperatures between 1000 and 3000 K, and pressures between 1 and 5 atm. These studies provided new insights into the temperature dependence of nitric oxide collision broadening, highlighting the inadequacies of the power law over a broad temperature range. With an accurate spectroscopic model over a broad temperature range, the quantitative two-color temperature sensing strategy was demonstrated in non-reactive shock tube experiments from 1000 to 3000 K to validate thermometry and during a nitric oxide formation experiment near 1700 K and 4 atm to highlight capability for temporally-resolved species measurements at MHz rates. The technique has applicability for sensing in a broad range of flow fields that involve high-temperature air.