Demonstration of Fluidic Throat Skewing for Thrust Vectoring in Structurally Fixed Nozzles

Abstract

The experimental demonstration of a fluidic, multi-axis thrust vectoring (MATV) scheme is presented for a structurally fixed, afterburning nozzle referred to as the conformal fluidic nozzle (CFN). This concept for jet flow control features symmetric injection around the nozzle throat to provide throttling for jet area control, and asymmetric injection to subsonically skew the sonic plane for jet vectoring. The conceptual development of the CFN was presented in a companion paper (Miller et al., 1999). In that study, critical design variables were shown to be the flap length and expansion area ratio of the nozzle, and the location, angle, and distribution of injected flow. Measures of merit were vectoring capability, gross thrust coefficient, and discharge coefficient. A demonstration of MATV was conducted on a 20%-scale CFN test article across a range of nozzle pressure ratios (NPR), injector flow rates, and flow distributions. Both yaw and pitch vector angles of greater than 8° were obtained at NPR of 5.5. Yaw vector angles greater than 10° were achieved at lower NPR. Values of thrust-coefficient for the CFN generally exceeded published measurements of shock-based, vectoring methods. In terms of vectoring effectiveness (ratio of vector angle to percent injected flow), fluidic throat skewing was found to be comparable to shock-based vectoring methods.

Computational Study of an Axisymmetric Dual Throat Fluidic Thrust Vectoring Nozzle for a Supersonic Aircraft Application

“…There are three primary mechanisms of fluidic thrust vectoring: shock-vector control, throat shifting, and counterflow [1][2][3][4][5][6][7][8][9][10][11][12][13] . These techniques can be used to vector the exhaust flow in the pitch and yaw directions.…”

“…Working best at off-design, over-expanded flow conditions, large thrust vector angles are generated with SVC techniques at the expense of system thrust ratio as the flow is robustly turned, and flow losses occur, through shocks in the nozzle. Throat shifting (TS) methods [8][9][10][11] more efficiently manipulate the subsonic flow upstream of the throat. This technique shifts and skews the nozzle throat plane by fluidic injection at the nozzle throat and typically achieve higher system thrust ratios than shockvector control methods, but usually generate smaller thrust vector angles.…”

Re-Educating Jet-Engine-Researchers to Stay Relevant

“…Fluidic JES Sum I: For small jet engines fluidic-JES harbors the following potential advantages: -reduced vehicle weight and cost (up to 50%), -reduced vehicle drag depending on tailless, wingbody-engine integration with embedded jet-engine stealth inlets of variants of those shown in Figure 4, -faster flight control responses, -fewer or no moving parts, actuators and deflecting surfaces, -less engine and vehicle maintenance, -lower radar cross section for improved stealth, dual throat nozzle options [20][21][22][23][24][25][26][27][28][29][30][31] produce somewhat larger jet deflecting angles and efficiencies than the other fluidic designs over the entire range of feasible Nozzle Pressure Ratios, -exhaust throat area adjustments by fluidic JES IFPC allow reduction to structurally fixed nozzles that cost Figure 5], require the engine exhausts to be moved aft to allow sidewise or up-down exhaust nozzles rotations required for unprecedented UCLASS VRT capabilities via mixed fluidic and mechanical JES, which are not yet available/fielded for ATTACK-STRIKE missions into highly congested areas -designs that are still being endlessly debated in U.S. design rooms and remain unfunded/unimplemented, unless one examines same in China. [4,5].…”

A Study on Operation Characteristics of Co-flow Fluidic Thrust Vector Control under Over-expanded Jet Condition

“…주유동과 같은 방향으로 제어유동을 분사하는 동 축류(Co-flow) (3,4) , 주유동과 반대방향으로 제어유 동을 분사하는 대향류(Counter-flow) (5) , 한쪽 노 즐벽면에서 수직으로 분사하는 충격파 방법 (Shock method) (6) , 양쪽 노즐벽면에서 분사하는 Throat-skewing (7) , 그리고 노즐 목이 2개로 구성 된 Dual throat method (8) 가 있다. Co (10) 의    모델에 Sarkar (11) 와 Wilcox (12) 의 압축성 효과를 추가하여 사용하였다.…”