Controlled flow regime transition in a dual bell nozzle by secondary radial injection
- PDF / 2,715,911 Bytes
- 15 Pages / 595.276 x 790.866 pts Page_size
- 15 Downloads / 161 Views
RESEARCH ARTICLE
Controlled flow regime transition in a dual bell nozzle by secondary radial injection L. Léger1 · V. Zmijanovic1 · M. Sellam2 · A. Chpoun2 Received: 9 July 2020 / Revised: 21 September 2020 / Accepted: 20 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract With the ever rising demands for cheaper payload delivery to orbit, dual bell nozzle with a potential theoretical performance gain of up to 10% can represents one of the major ways of advance to achieve the goal. The well-known transition unsteadiness in a dual-bell rocket nozzle represents one of the major concerns for the development of such altitude compensating type nozzle (ACN). The present study proposes and investigates the possibilities of secondary radial injection for flow regime transition control. Present experimental results demonstrate potential effects of secondary injection on transition and re-transition control even with a relatively low secondary injection mass flow rates. Doing so, the transition and retransition process were significantly delayed towards the ideal transition point. In addition, side loads have been found to be greatly decreased or even eliminated. Graphic abstract
* L. Léger luc.leger@univ‑orleans.fr 1
ICARE, CNRS, Orleans, France
LMEE, University of Evry, Université Paris-Saclay, Evry, France
2
1 Introduction To insure the launch reliability, the main stage engine of a modern parallel heavy satellite launcher is ignited before the booster’s ignition. Thus, the main stage engine
13
Vol.:(0123456789)
246
Page 2 of 15
operates from sea level up to almost vacuum conditions. To limit flow separation phenomena in the divergent part of the exhaust nozzle at sea level, its section area ratio has to be restricted. This limitation results in performance losses at high altitude. In a theoretical approach to this issue, a continuous variation of the expansion ratio, using a changing geometry nozzle would be an ideal response to the adaptation issues. However, manufacturing such nozzle is a difficult engineering task. The interest in the dual-bell nozzle (DBN), as an altitude compensating device (Hagemann et al. 1998, 2002; Frey and Hagemann 1999) with a potential theoretical performance gain of up to 10%, has resurfaced in the last 2 decades. The dual-bell nozzle is an attractive candidate for practical applications motivated by the rising demands for a cheaper payload delivery. The dual-bell nozzle consists of a base component (contour) and an extension linked as such an abrupt change in wall contour is induced. This particular geometry is conceived to insure two operating modes (Fig. 1a). First, at lower initial altitudes, because of the high ambient pressure, before the first altitude adaptation, the flow inside the nozzle is over-expanded and separates at the geometric inflection point. The contour slope discontinuity has a stabilizing effect by symmetrizing the separation line. This results a mitigation of harmful side loads. During the ascent, the external pre
Data Loading...
