Forward-running detonation drivers for high-enthalpy shock tunnels

Abstract

To improve the quality of driving ows generated with detonation-driven shock tunnels operated in the forwardrunning mode, various detonation drivers with specially designed sections were examined. Four con gurations of the specially designed section, three with different converging angles and one with a cavity ring, were simulated by solving the Euler equations implemented with a pseudo kinetic reaction model. From the rst three cases, it is observed that the re ection of detonation fronts at the converging wall results in an upstream-traveling shock wave that can increase the ow pressure that has decreased due to expansion waves, which leads to improvement of the driving ow. The con guration with a cavity ring is found to be more promising because the upstream-traveling shock wave appears stronger and the detonation front is less overdriven. Although pressure uctuations due to shock wave focusing and shock wave re ection are observable in these detonation-drivers, they attenuate very rapidly to an acceptable level as the detonation wave propagates downstream. Based on the numerical observations, a new detonation-driven shock tunnel with a cavity ring is designed and installed for experimental investigation. Experimental results con rm the conclusion drawn from numerical simulations. The generated driving ow in this shock tunnel could maintain uniformity for as long as 4 ms. Feasibility of the proposed detonation driver for high-enthalpy shock tunnels is well demonstrated. NomenclatureD CJ = Chapman-Jouguet (C-J) detonation velocity e = total energy per mass= molecular weight of the reactant m 2 = molecular weight of the product P CJ = C-J detonation pressure P i = initial pressure in driver section P ignit = ignition pressure P 0 = initial pressure in driven section p = pressure Q = reaction heat per mass S, H = source terms= mass fraction of the reactant Z 2 = mass fraction of the product ®,¯, Adet = tuned constants of reaction model°= effective adiabatic exponent°1 = adiabatic exponent of the reactant°2 = adiabatic exponent of the product 1s = local mesh size

On theory and methods for advanced detonation-driven hypervelocity shock tunnels

“…A driven section is also appended to the closed end of the detonation tube to get a stable incident shock wave. This concept of the backward detonation-driven shock tunnel with a damping section was applied successfully to the TH2-D high-enthalpy shock tunnel in the Aachen University of Technology [ 12 ], and then to the JF-10 shock tunnel in the Institute of Mechanics, CAS [ 13 ].…”

“…proposed the Forward Detonation Cavity (FDC) driver, as schematically shown in Fig. 6 , based on the shock reflection concept [ 13 ]. The FDC driver consists of three parts: the detonation driver, the reflecting cavity and the auxiliary detonation driver.…”

“…The uniformity of the pressure distribution shows that the FDC driver successfully eliminates the incident shock attenuation caused by the Taylor expansion wave, and fluctuations around the average pressure damp rapidly in the driven section. The 6 ms test time demonstrated excellent performance of the JF-10 shock tunnel, which is only about 25 m long [ 13 ].…”

Survey of high-enthalpy shock facilities in the perspective of radiation and chemical kinetics investigations

“…The performances of JF-10 have been investigated by Zhao et al [132], and Jiang et al [133]. Stagnation pressure up to 25 MPa, total enthalpy is in the range 15 up to 25 MJ/kg, and Reynolds numbers of 4 Â 10 7 can be achieved in this facility.…”

Numerical investigation on detonation cell evolution in a channel with area-changing cross section

“…The scheme was applied successfully in detonation simulation with the one-step reaction models [7,8] , and the further extension was made to investigate effects of flow expansion and compression on cellular detonation cell to gain better understanding of the interaction among the reaction zone, the chemical reaction rate and the wave front structure.…”