Wall pressure and thrust of a dual bell nozzle in a cold gas facility

Abstract

A dual-bell nozzle has been tested in the ONERA-R2Ch wind tunnel within the CNES PERSEUS program. The wall pressure distributions and the thrust for the two §ow regimes have been characterized in the nozzle pressure ratio (NPR) range from 51 up to 597. A hysteresis on the transition NPR between the two §ow regimes has been observed according to the evolution of NPR. The duration for the switch between the two §ow regimes is less than 10 ms. The hysteresis of about 20% on the NPR has also a direct e¨ect on the thrust. The total thrust of the dual-bell nozzle becomes higher than the thrust of the isolated base nozzle without extension for NPR > 1500. The hysteresis phenomenon has been modeled with the use of supersonic separation criteria and by making the assumption that incipient separation occurs immediately after the transition for increasing NPRs, while e¨ective separation occurs just before the transition for decreasing NPRs.

Unsteady Flow Conditions During Dual-Bell Sneak Transition

“…Since the early 1990s, a lot of computational [5,9] and experimental [6][7][10][11][12][13][14][15] studies have been initiated to understand the various flow phenomenon associated with DB operation and looked for possible means to control them. The renewed interest in this nozzle research is primarily due to the fact that the DB nozzle is the most promising and feasible candidate for an altitude-compensating cryogenic main engine.…”

Numerical Investigation of Supersonic Flows on Innovative Nozzles (Dual Bell Nozzle)

“…Note that it is at this pressure ratio (NPR=806) that this nozzle has been optimized. The Iso-Mach contours of the our dual bell nozzle are very similar to those of (Reijasse et al 2011) which allowed us to judge the good reproduction of the geometry and the good implementation of our model under Fluent (geometry, mesh, boundary condition, and solution methods).…”

“…In order to validate our Mach field, Fig. 6 shows the Mach field in the same nozzle obtained by Reijasse et al (2011). It shows that the flow clings entirely to the wall, which indicates that the flow is not detached.…”

“…Several simulation calculations were performed in an inviscid stationary axisymmetric model. These simulations allowed a first validation of the numerical results against the results of reference (Reijasse et al 2011) to comprehend the sensitivity of this type of flow to predefined boundary conditions. Table 2 represents…”

Sea-level transitioning dual bell nozzles

“…[39] In the following one and a half decades the work mainly focused on the dual bell flow behaviour itself. Experimentally, the performance [16][17][18], the transition/sneak transition [19][20][21][22][23][24], the hysteresis/buffeting effect [18,21,25], the side loads [26], and the heat loads [27] were studied. Numerically, the transition/sneak transition [24,[28][29][30][31][32][33][34], the hysteresis/buffeting effect [30,35], the side loads [30,33], the heat loads [24], and the jet oscillation [36] were studied as well.…”