Numerical and Engine Cycle Analyses of a Pulse Laser Ramjet Vehicle

Abstract

A preliminary feasibility study of a laser ramjet SSTO has been conducted using engine cycle analysis. Although a large amount of laser energy is lost due to chemically frozen flow at high altitudes, the laser ramjet SSTO was found to be feasible with 100 MW laser power for 100 kg vehicle mass and 1 m 2 vehicle cross-section area. Obtained momentum coupling coefficient, C m , was validated by means of CFD. As a result, the engine cycle analysis was underestimating C m. This would be because of the strong unsteady energy input in the actual heating process and the spatially localized pressure on the afterbody.

Pulse-Laser Powered Orbital Launcher

“…A blast wave is again driven by an explosion source model with η bw which depends on atmospheric pressure (Katsurayama et al, 2009). Figure 8 shows a part of computational results, and these results (Katsurayama et al, 2003) have showen that C m in the ramjet mode is insensitive to laser energy E L and depends only on flight conditions. Therefore, the performance is obtained from the map of C m ,w h i c hi s constructed using CFD analyses under the conditions of 16 pairs of atmospheric density ρ ∞ and flight Mach number M ∞ .T h em a po fC m is shown in Fig.…”

“…C m during the laser ramjet mode was computed in our previous CFD analyses (Katsurayama et al, 2003). A blast wave is again driven by an explosion source model with η bw which depends on atmospheric pressure (Katsurayama et al, 2009).…”

“…The apex angle of the nozzle cone α is set to 30°which is almost equivalent to the value of the Lightcraft used in the CFD analysis of the ramjet mode. The value of η bw in the rocket mode is calculated analytically by solving the propagation of a LSD in hydrogen propellant using our previous numerical model (Katsurayama et al, 2003) obtained by combining a plain Chapman-Jouguet detonation relation and chemical equilibrium calculation, resulting in η bw,rocket = 23.5%.…”

“…However, in an air-breathing propulsion system, the energy conversion efficiency evidently depends on its flight trajectory. The present article introduces our realistic performance modeling in three flight modes: the performance in the pulsejet mode is modeled using measured energy conversion efficiency and Computational Fluid Dynamics (CFD) analysis (Katsurayama et al, 2008); the performance during the ramjet mode is computed using CFD analysis (Katsurayama et al, 2003); and the performance in the rocket mode is obtained analytically with the energy conversion efficiency computed using a thermochemical equilibrium calculation (Katsurayama et al, 2003). In addition, a transfer trajectory to the GEO is proposed.…”

Energy Transmission in Space Using an Optical Phased Array

“…[1][2][3][4][5][6][7][8] Because laser beams are more advantageous in directionality than microwaves, high power and large-scale lasers such as free electron lasers 9) and solid lasers are under development for directed energy systems, and long-range transmission methods such as a non-diffracting single-aperture beam 10) have been proposed. However, there are several obstacles in the scaling up of a laser oscillator: In general, with the increase in power and size of a laser oscillator, it becomes expensive and difficult to oscillate in a single transverse mode to produce optimum beam collimation.…”