Side Thrust Control by Secondary Gas Injection into Rocket Nozzles

Abstract

Directional control of rockets can be achieved by using secondary gas jets for providing side forces. The present investigation is concerned with the fact that a greater side force can be achieved by expanding the secondary gas into the supersonic region of the main nozzle than by expanding it directly to atmosphere. A laboratory test rig using ambient temperature air for the primary and secondary flows is described. Axial thrust and side force were measured using strain gauge force transducers. The experiments were performed on a small axisymmetric main nozzle with a 10° semi-angle of divergence and with sonic injection through circular ports placed normal to the main nozzle axis. The investigations centred principally on the effects of (1) varying the secondary port size at a given axial location in the nozzle and of (2) varying the axial location of a port of constant diameter. Side force and axial thrust augmentation characteristics were obtained for a range of primary and secondary flow inlet pressures. The results show the relative importance of the parameters on which side force depends, the maximum side force that may be produced and the interdependence of axial thrust augmentation and side force.

Experimental–Numerical Parametric Investigation of a Rocket Nozzle Secondary Injection Thrust Vectoring

“…With further increase in injection, C AV decays. This complies well with [23] and in [44] on 2-D nozzle slot injection, where a higher injection-performance ratio is noticed for the injection rate ratios between two and four.…”

“…Compared to the fundamental cases of slot and circular sonic injections at the flat plate, the secondary injection inside a rocket nozzle is distinguished by the strong wall-bounded supersonic crossflow character, as was also reported in [20][21][22][23][24]. The internal effects of the lateral sides of the wall and the possible main shock reflection further affect the complex interaction crossflow field.…”

Secondary Gas Injection into Rocket Nozzles through Ports Mutually at Right Angles

“…The nozzle was attached to a thrust rig described in detail in ref. 1. The side force was measured using a Strain gauge transducer and the arrangement was such that side force could only be measured in a vertical plane containing the main nozzle axis.…”

Development of Gas Dynamic Nozzles: A Preliminary Computational Study

“…Shigeru Aso et al [14] showed that, for slotted injection, the effect of aerodynamic fences has to be considered. Neilson et al [15] studied the effect of fluidic injection in rocket nozzles and Louis A. Cassel [16] studied the response of aircraft under an ambient atmospheric environment. Bernhard Stahl and Helmut Esch [17] experimentally measured the wall pressures for distinct flow injection setups.…”