Design and Preliminary Analysis of the Variable Axisymmetric Divergent Bypass Dual Throat Nozzle

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Yangsheng Wang ◽  
Jinglei Xu ◽  
Shuai Huang ◽  
Jingjing Jiang ◽  
Ruifeng Pan
Keyword(s):  
Pressure Ratio ◽  
Variable Geometry ◽  
Nozzle Throat ◽  
Thrust Coefficient ◽  
Thrust Vectoring ◽  
Turbofan Engines ◽  
Original Variable ◽  
Adaptive Capability ◽  
Thrust Vector ◽  
Overall Performance

Abstract Turbofan engines with afterburners usually have variable nozzle throat area, and the nozzle throat area may increase by 50–100% during afterburning. An axisymmetric divergent bypass dual throat nozzle (ADBDTN) can offer high thrust vectoring efficiency without requiring additional secondary flow in the pitch and yaw directions. In this study, a variable ADBDTN configuration with flow adaptive capability, wide nozzle throat area adjustment range, and excellent overall performance was designed and investigated numerically. The nozzle throat and exit area can be controlled mechanically, while thrust vectoring is achieved via fluidic methods. Both the original variable geometry schemes and their corresponding improved schemes, namely, “slider-rocker mechanism & rotation” (SRM-R) and “slider-rocker mechanism & slide” (SRM-S) schemes, along with their improved schemes, were proposed and investigated. Results indicated that compared to the original variable geometry schemes, the nozzle configurations with improved variable geometry schemes not only achieve 50% increase in the nozzle throat area but also acquire flow adaptive capability and excellent overall performance by appropriately adjusting the nozzle exit area. At a nozzle pressure ratio (NPR) of 4.47, the highest thrust coefficient reaches 0.940; the largest pitch thrust-vector angle is 19.52 deg; and the discharge coefficients are 0.968 and 0.970 under the nonafterburning and afterburning states, respectively. In addition, compared to the improved SRM-R scheme, the nozzle configuration with improved SRM-S scheme possesses better overall performance.

An Investigation of Flow Characteristics and Parameter Effects for a New Concept of Hybrid SVC Nozzle

2018 ◽  
Author(s):  
F. Song ◽  
J. W. Shi ◽  
L. Zhou ◽  
Z. X. Wang ◽  
X. B. Zhang
Keyword(s):  
Static Pressure ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Exhaust System ◽  
Aircraft Engine ◽  
Thrust Coefficient ◽  
Thrust Vectoring ◽  
Static Pressure Distribution ◽  
Thrust Vector ◽  
Vector Angle

Lighter weight, simpler structure, higher vectoring efficiency and faster vector response are recent trends in development of aircraft engine exhaust system. To meet these new challenges, a concept of hybrid SVC nozzle was proposed in this work to achieve thrust vectoring by adopting a rotatable valve and by introducing a secondary flow injection. In this paper, we numerically investigated the flow mechanism of the hybrid SVC nozzle. Nozzle performance (e.g. the thrust vector angle and the thrust coefficient) was studied with consideration of the influence of aerodynamic and geometric parameters, such as the nozzle pressure ratio (NPR), the secondary pressure ratio (SPR) and the deflection angle of the rotatable valve (θ). The numerical results indicate that the introductions of the rotatable valve and the secondary injection induce an asymmetrically distributed static pressure to nozzle internal walls. Such static pressure distribution generates a side force on the primary flow, thereby achieving thrust vectoring. Both the thrust vector angle and vectoring efficiency can be enhanced by reducing NPR or by increasing θ. A maximum vector angle of 16.7 ° is attained while NPR is 3 and the corresponding vectoring efficiency is 6.33 °/%. The vector angle first increases and then decreases along with the elevation of SPR, and there exists an optimum value of SPR for maximum thrust vector angle. The effects of θ and SPR on the thrust coefficient were found to be insignificant. The rotatable valve can be utilized to improve vectoring efficiency and to control the vector angle as expected.

Optimizing Separate Exhaust Turbofans for Cruise Specific Fuel Consumption

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Syed J. Khalid
Keyword(s):  
Fuel Consumption ◽  
Control Algorithm ◽  
Velocity Ratio ◽  
Transmission Efficiency ◽  
Specific Fuel Consumption ◽  
Variable Geometry ◽  
Nozzle Throat ◽  
Propulsive Efficiency ◽  
Turbofan Engines ◽  
Bypass Ratio

Cruise specific fuel consumption (SFC) of turbofan engines is a key metric for increasing airline profitability and for reducing CO2 emissions. Although increasing design bypass ratio (BPR) of separate exhaust turbofan configurations improves cruise SFC, further improvements can be obtained with online control actuated variable geometry modulations of bypass nozzle throat area, core nozzle throat area, and compressor variable vanes (CVV/CVG). The scope of this paper is to show only the benefits possible, and the process used in determining those benefits, and not to suggest any particular control algorithm for searching the best combination of the control effectors. A parametric cycle study indicated that the effector modulations could increase the cruise BPR, core efficiency, transmission efficiency, propulsive efficiency, and ideal velocity ratio resulting in a cruise SFC improvement of as much as 2.6% depending upon the engine configuration. The changes in these metrics with control effector variations will be presented. Scheduling of CVV is already possible in legacy digital controls; perturbation to this schedule and modulation of nozzle areas should be explored in light of the low bandwidth requirements at steady-state cruise conditions.

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

2001 ◽  
Vol 123 (3) ◽  
pp. 502-507 ◽  
Author(s):  
P. J. Yagle ◽  
D. N. Miller ◽  
K. B. Ginn ◽  
J. W. Hamstra
Keyword(s):  
Conceptual Development ◽  
Discharge Coefficient ◽  
Companion Paper ◽  
Nozzle Throat ◽  
Thrust Coefficient ◽  
Thrust Vectoring ◽  
Flow Rates ◽  
Critical Design ◽  
Design Variables ◽  
Nozzle Pressure

The experimental demonstration of a fluidic, multiaxis 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. [1]). 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 percent 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 deg were obtained at NPR of 5.5. Yaw vector angles greater than 10 deg 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.

Optimizing Separate Exhaust Turbofans for Cruise Specific Fuel Consumption

2016 ◽  
Author(s):  
Syed Khalid
Keyword(s):  
Fuel Consumption ◽  
Control Algorithm ◽  
Velocity Ratio ◽  
Transmission Efficiency ◽  
Specific Fuel Consumption ◽  
Variable Geometry ◽  
Nozzle Throat ◽  
Propulsive Efficiency ◽  
Turbofan Engines ◽  
Bypass Ratio

Cruise specific fuel consumption (SFC) of turbofan engines is a key metric for increasing airline profitability and for reducing CO2 emissions. Although increasing design bypass ratio (BPR) of separate exhaust turbofan configurations improves cruise SFC, further improvements can be obtained with control actuated variable geometry modulations of core nozzle throat area, bypass nozzle throat area, and compressor variable vanes (CVV). The scope of this paper is to show only the benefits possible, and the process used in determining those benefits, and not to suggest any particular control algorithm for searching the best combination of the control effectors. A parametric cycle study indicated that the effector modulations could increase the cruise BPR, core efficiency, transmission efficiency, propulsive efficiency, and ideal velocity ratio resulting in a cruise SFC improvement of as much as 2.6% depending upon the engine configuration. The changes in these metrics with control effector variations will be presented. Modulation of CVV is already possible in legacy digital controls, and modulation of nozzle areas should be explored in light of the low bandwidth requirements at steady-state cruise conditions.

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

2000 ◽  
Author(s):  
Patrick J. Yagle ◽  
Daniel N. Miller ◽  
K. Brant Ginn ◽  
Jeffrey W. Hamstra
Keyword(s):  
Conceptual Development ◽  
Discharge Coefficient ◽  
Companion Paper ◽  
Nozzle Throat ◽  
Thrust Coefficient ◽  
Thrust Vectoring ◽  
Flow Rates ◽  
Critical Design ◽  
Design Variables ◽  
Nozzle Pressure

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.

Theoretical and Numerical Studies on the Performance of Shock Vector Control

2019 ◽  
Author(s):  
Kexin Wu ◽  
HeuyDong Kim
Keyword(s):  
Experimental Data ◽  
Vector Control ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Symmetry Plane ◽  
Control Effect ◽  
Thrust Coefficient ◽  
Thrust Vector Control ◽  
Pressure Distributions ◽  
Thrust Vector

Abstract The transverse injection into a supersonic flow is a significant application that appeared in numerous aerodynamic applications, such as drag reduction and fluidic thrust vectoring control. Nowadays, fluidic thrust vector control is gradually replacing mechanical thrust vector control to redirect various air vehicles. Shock vector control is very popular in fluidic thrust vector control field due to lots of advantages, such as simple structure, more integrated control effect, and quick vectoring response. In present works, numerical simulations and theoretical analyses were conducted to investigate the shock vectoring performance in a three-dimensional rectangular nozzle. To validate the reliability and accuracy of the present numerical methodology, static pressure distributions along upper and lower nozzle surfaces in the symmetry plane were compared with experimental data published by NASA. It was evident that present numerical results present great approximations with experimental data. Control variables of the slot injector were studied, which not only include slot length and slot width but also contain uniform mass flow ratio and injection pressure ratio. Performance variations were illustrated clearly, such as static pressure distributions along upper and lower nozzle surfaces, deflection angle, resultant thrust coefficient, and thrust efficiency. Useful conclusions were obtained for further investigations on shock vector control.

Experimental evaluation and numerical simulation of performance of the bypass dual throat nozzle

2020 ◽  
pp. 095441002095988
Author(s):  
Mohammad Hadi Hamedi-Estakhrsar ◽  
Hossein Mahdavy-Moghaddam
Keyword(s):  
Numerical Simulation ◽  
Discharge Coefficient ◽  
Deflection Angle ◽  
Pressure Ratio ◽  
Modern Concept ◽  
Thrust Coefficient ◽  
Thrust Vector Control ◽  
Nozzle Pressure ◽  
Thrust Vector ◽  
Turbulent Air Flow

Bypass dual throat nozzle (BDTN) is a modern concept of fluidic thrust vector control. This method able to solve the problem of thrust loss without need the secondary mass flow from other part of engine. Internal nozzle performance and thrust vector angles have been measured in the BDTN experimentally and numerically. A new simple approach is proposed to detect the thrust deflection angle. Numerical simulation of 3-D turbulent air flow is carried out by using the RNG k-e turbulence model. The obtained results of thrust coefficient, discharge coefficient and thrust deflection angle have been validated by comparing with measured experimental data. The results show that for nozzle pressure ratio of 1–4 the tested nozzle able to deflect the thrust vector of 26.5°-19°. By increasing NPR from 2 up to 4, the thrust coefficient values will change in the range of 0.85-0.93. Also the effect of different positions of the bypass channel on the BDTN performance parameters has been investigated numerically. The predicted results show that the BDTN configuration with bypass duct on the first nozzle throat has the highest value of thrust deflection angle over the range of NPRs.

scholarly journals Influence of Seal Cavity Leakage Flow on Compressor Performance Investigated with a Circumferentially Averaged Method

2021 ◽  
Vol 11 (2) ◽  
pp. 780
Author(s):  
Dong Liang ◽  
Xingmin Gui ◽  
Donghai Jin
Keyword(s):  
Flow Field ◽  
Pressure Ratio ◽  
Interaction Mechanism ◽  
Main Flow ◽  
Leakage Flow ◽  
Destructive Effect ◽  
Through Flow ◽  
Compressor Performance ◽  
Overall Performance ◽  
Flow Blockage

In order to investigate the effect of seal cavity leakage flow on a compressor’s performance and the interaction mechanism between the leakage flow and the main flow, a one-stage compressor with a cavity under the shrouded stator was numerically simulated using an inhouse circumferentially averaged through flow program. The leakage flow from the shrouded stator cavity was calculated simultaneously with main flow in an integrated manner. The results indicate that the seal cavity leakage flow has a significant impact on the overall performance of the compressor. For a leakage of 0.2% of incoming flow, the decrease in the total pressure ratio was 2% and the reduction of efficiency was 1.9 points. Spanwise distribution of the flow field variables of the shrouded stator shows that the leakage flow leads to an increased flow blockage near the hub, resulting in drop of stator performance, as well as a certain destructive effect on the flow field of the main passage.

A New Method of Modeling Underexpanded Exhaust Plumes for Wind Tunnel Aerodynamic Testing

1989 ◽  
Vol 111 (4) ◽  
pp. 748-754
Author(s):  
V. Salemann ◽  
J. M. Williams
Keyword(s):  
Wind Tunnel ◽  
Free Stream ◽  
Dynamic Pressure ◽  
Pressure Ratio ◽  
Area Ratio ◽  
Full Scale ◽  
New Method ◽  
Thrust Coefficient ◽  
Model Scale ◽  
Exhaust Plumes

A new method for modeling hot underexpanded exhaust plumes with cold model scale plumes in aerodynamic wind tunnel testing has been developed. The method is applicable to aeropropulsion testing where significant interaction between the exhaust and the free stream and aftbody may be present. The technique scales the model and nozzle external geometry, including the nozzle exit area, matches the model jet to free-stream dynamic pressure ratio to full-scale jet to free-stream dynamic pressure ratio, and matches the model thrust coefficient to full-scale thrust coefficient. The technique does not require scaling of the internal nozzle geometry. A generalized method of characteristic computer code was used to predict the plume shapes of a hot (γ = 1.2) half-scale nozzle of area ratio 3.2 and of a cold (γ = 1.4) model scale nozzle of area ratio 1.3, whose pressure ratio and area ratio were selected to satisfy the above criteria and other testing requirements. The plume shapes showed good agreement. Code validity was checked by comparing code results for cold air exhausting into a quiescent atmosphere to pilot surveys and shadowgraphs of model nozzle plumes taken in a static facility.

Numerical Investigation of Cowl Lip Adjustments for a Rocket-Based Combined-Cycle Inlet in Takeoff Regime

2016 ◽  
Vol 33 (3) ◽  
Author(s):  
Lei Shi ◽  
Xiaowei Liu ◽  
Guoqiang He ◽  
Fei Qin ◽  
Xianggeng Wei ◽  
...  
Keyword(s):  
Numerical Integration ◽  
Numerical Investigation ◽  
Flow Separation ◽  
Static Condition ◽  
Combined Cycle ◽  
Variable Geometry ◽  
Overall Performance ◽  
Negative Impacts

AbstractNumerical integration simulations were performed on a ready-made central strut-based rocket-based combined-cycle (RBCC) engine operating in the ejector mode during the takeoff regime. The effective principles of various cowl lip positions and shapes on the inlet operation and the overall performance of the entire engine were investigated in detail. Under the static condition, reverse cowl lip rotation in a certain range was found to contribute comprehensive improvement to the RBCC inlet and the entire engine. However, the reverse rotation of the cowl lip contributed very little enhancement of the RBCC inlet under the low subsonic flight regime and induced extremely negative impacts in the high subsonic flight regime, especially in terms of a significant increase in the drag of the inlet. Changes to the cowl lip shape provided little improvement to the overall performance of the RBCC engine, merely shifting the location of the leeward area inside the RBCC inlet, as well as the flow separation and eddy, but not relieving or eliminating those phenomena. The results of this study indicate that proper cowl lip rotation offers an efficient variable geometry scheme for a RBCC inlet in the takeoff regime.

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