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.

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.

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.

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.

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.

A Numerical Study on the Sensitivity of the Discrete Element Method for Hopper Discharge

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
H. Kruggel-Emden ◽  
S. Rickelt ◽  
S. Wirtz ◽  
V. Scherer
Keyword(s):  
Discrete Element Method ◽  
Numerical Study ◽  
Discrete Element ◽  
Tangential Direction ◽  
Flow Properties ◽  
Friction Coefficients ◽  
Flow Rates ◽  
Design Variables ◽  
Side Walls ◽  
Element Method

Based on the time-driven discrete element method, granular flow within a hopper is investigated. The main focus is thereby set on hopper vessel design variables such as discharge rates and applied wall pressures. Within the used model contacts are assumed as linear viscoelastic in normal and frictional-elastic in tangential direction. The hopper geometry is chosen according to Yang and Hsiau (2001, “The Simulation and Experimental Study of Granular Materials Discharged From a Silo With the Placement of Inserts,” Powder Technol., 120(3), pp. 244–255), who performed both experimental and numerical investigations. The considered setup is attractive because it involves only a small number of particles enabling fast modeling. However, the results on the experimental flow rates reported are contradictory and are afflicted with errors. By an analysis of the hopper fill levels at different points of time, the correct average discharge times and flow rates are obtained. Own simulation results are in good agreement with the experimental flow rates and discharge times determined. Based on the thereby defined set of simulation parameters, a sensitivity analysis of parameters such as friction coefficients, stiffnesses, and time steps is performed. As flow properties, besides the overall discharge times, the discharge time averaged axial and radial velocity distributions within the hopper and the normal stresses on the side walls during the first seconds of discharge are considered. The results show a strong connection of the friction coefficients with the discharge times, the velocity distributions, and the stresses on the side walls. Other parameters only reveal a weak often indifferent influence on the studied flow properties.

Pressure Drop, Air Entrainment and Moments of the Axial Velocity in the Laminar-Turbulent Transition Jet Flow in Domestic Gas Injectors

2021 ◽  
Author(s):  
William Alexander Carrillo Ibañez ◽  
Márcio Demétrio ◽  
Amir Oliveira ◽  
Fernando Pereira
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Axial Velocity ◽  
Energy Flow ◽  
Discharge Coefficient ◽  
Mixing Layer ◽  
Air Entrainment ◽  
Flow Rates ◽  
Free Jet ◽  
Internal Mixing

Abstract This works aims at characterizing the flow in the outlet of three gas injectors used in atmospheric burners and developing correlations for the discharge coefficient, air entrainment, momentum and energy flow rates. These devices have millimeter sized orifices, a cup-like region at the injector outlet and the flow occurs in the transition from the laminar to the fully turbulent regimes. The pressure drop was measured and correlated as a function of the orifice Reynolds number for the three injectors. The correlations are able to predict the discharge coefficient within ± 5% deviation from the measurements in the range 90 < Re < 4400. The axial velocity and turbulent intensity were measured at the outlet of the injectors using a hot-wire anemometer at the orifice Reynolds number of 3060, which is typical of the applications. The measurements were compared to CFD solutions using the gamma - Re-theta RANS transition model in the STAR-CCM+ commercial package. The results indicate the strong influence of the shape of the outlet cup-like region of the injectors in the development of an internal mixing layer and the external mixing layer in the free jet. The momentum and energy flow rates for the injector model with the largest cup are reduced to 50% and 21%, respectively, of the simplest gas injector. However, the gas jet in this injector carries 28% of the stoichiometric air before leaving the cup. These aspects must be taken into account in the preliminary design of atmospheric burners.

A Shock-Tube Technique to Determine Steady-Flow Losses of Orifices and Other Duct Elements

1960 ◽  
Vol 82 (1) ◽  
pp. 195-200 ◽  
Author(s):  
George Rudinger
Keyword(s):  
Shock Tube ◽  
Steady Flow ◽  
Discharge Coefficient ◽  
Initial Conditions ◽  
Test Element ◽  
Pressure Measurements ◽  
Flow Data ◽  
Flow Rates ◽  
Flow Losses ◽  
Good Agreement

It is shown that a simple shock tube is capable of producing appreciable steady-flow rates through a short duct element, such as an orifice, a valve, or a screen. The flow upstream and downstream of the test element and, therefore, also the losses caused by the test element, can be calculated from known initial conditions in the shock tube and pressure measurements at one point upstream of the element. Experiments to determine the discharge coefficient of a sharp-edged orifice are described as an illustration of the method. The results are in good agreement with available steady-flow data.

Influence of the pressure relief door area and aspect ratio on discharge and force characteristics

2019 ◽  
Vol 92 (2) ◽  
pp. 107-116
Author(s):  
Shiyu Feng ◽  
Chenchen Wang ◽  
Xiaotian Peng ◽  
Yan Yan ◽  
Yang Deng ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Discharge Coefficient ◽  
Geometric Parameters ◽  
Pressure Relief ◽  
Thrust Coefficient ◽  
Content Type ◽  
Moment Coefficient ◽  
The Moment ◽  
Compartment Pressures ◽  
Force Characteristics

Purpose The purpose of this paper is to analyze the effects of the PRD geometric parameters, including the area and aspect ratio, on the discharge and force characteristics of pressure relief process under various plenum compartment pressures and Mach numbers. Design/methodology/approach Under various plenum compartment pressures and Mach numbers, the effect of the area and aspect ratio on the discharge and force characteristics of the PRD are numerically investigated via a three-dimensional steady Reynolds-averaged Navier–Stokes equations solver based on structured grid technology. Findings When the aspect ratio remains constant, the discharge coefficient CD, thrust coefficient CT and moment coefficient CM are not affected by the PRD. When the area is constant, the aspect ratio dramatically impacts the discharge and force characteristics because the aspect ratio increases, the discharge coefficient CD of the PRD decreases, and the thrust coefficient CT and the moment coefficient CM both increase. When the aspect ratio is 2, the discharge coefficient CD decreases by 14.7 per cent, the thrust coefficient CT increases by 10-15 per cent, and the moment coefficient CM increases by 10-23 per cent compared with when the aspect ratio is 1. Practical implications This study provides detailed data and conclusions for nacelle PRD researchers and actual engineering applications. Originality/value On the basis of considering the influence of operating conditions on the discharge and force characteristics of the nacelle PRD, the impact of geometric parameters, including the area and aspect ratio on the discharge and force characteristics is comprehensively considered.

Thermosyphon Models for Downhole Heat Exchanger Applications in Shallow Geothermal Systems

1978 ◽  
Vol 100 (4) ◽  
pp. 713-719 ◽  
Author(s):  
D. B. Kreitlow ◽  
G. M. Reistad ◽  
C. R. Miles ◽  
G. G. Culver
Keyword(s):  
Heat Exchanger ◽  
Analytical Models ◽  
Geothermal Systems ◽  
Flow Rates ◽  
Estimated Parameters ◽  
Design Variables ◽  
Circulation Mechanism ◽  
Geothermal Wells ◽  
Experimental Values ◽  
Theoretical Results

The analysis of downhole heat exchangers used to extract energy from relatively shallow geothermal wells leads to the consideration of several interesting problems of buoyancy-driven heat transfer in enclosures. This paper considers thermosyphoning through and around the wellbore casing which is perforated at two or more depths. Analytical models are developed for thermosyphoning in the cased well both with and without a heat exchanger installed. Theoretical results are compared with experimental values. These comparisons show that the observed energy extraction rates and flow rates through the well casing are possible with thermosyphoning as the only circulation mechanism within the well bore. The model with a heat exchanger installed is parametrically evaluated to illustrate the sensitivity of the model to estimated parameters and the effect of changes in design variables or constraints.

Numerical parametric study on three-dimensional rectangular counter-flow thrust vectoring control

2020 ◽  
Vol 234 (16) ◽  
pp. 2221-2247 ◽  
Author(s):  
Kexin Wu ◽  
Guang Zhang ◽  
Tae Ho Kim ◽  
Heuy Dong Kim
Keyword(s):  
Mach Number ◽  
Shear Layer ◽  
Static Pressure ◽  
Three Dimensional ◽  
Critical Parameters ◽  
Mechanical Equipment ◽  
Counter Flow ◽  
Thrust Coefficient ◽  
Thrust Vectoring ◽  
Gap Height

Recently, fluidic thrust vectoring control is popular for micro space launcher propulsion systems due to its several advantages, such as fast dynamic responsiveness, better control effectiveness, and no moving mechanical equipment. Counter-flow thrust vectoring control is an especially effective technique by utilizing less suction flow to control the mainstream deflection flexibly. In the current work, theoretical and numerical analyses are performed together to elaborate on the performance of the three-dimensional rectangular counter-flow thrust vectoring control system. A new propulsion nozzle of Mach 2.5 is devised by method of characteristics. To testify the feasibility and accuracy of the present research methodology, numerical results were validated against experimental data from the open literature. The computational result using the standard k-epsilon turbulence model reveals a good match with experimentally measured static pressure values along the centerline of the upper suction collar. The influence of several key parameters on vectoring performance is investigated herein, including the mainstream temperature, collar radius, horizontal collar length, and gap height. Critical parameters have been quantitatively analyzed, such as static pressure distribution along the centerline of the upper suction collar, pitching angle, suction mass flow ratio, and thrust coefficient. Furthermore, the flow-field features are qualitatively expounded based on the static pressure contour, streamline, iso-turbulent kinetic energy contour, and iso-Mach number contour. Some important conclusions are offered for further studies. The mainstream temperature mainly affects different dynamic characteristics of the mixing shear layer, including the convective Mach number of the shear layer, density ratio, and flow velocity ratio. The collar radius influences the pressure gradient near the suction collar surface significantly. The pitching angle increases rapidly with the increasing collar radius. As the horizontal collar length increases, the systematic deflection angle initially increases then decreases. The highest pitching angle is obtained for L/ H = 3.53. With regard to the gap height, a larger gap height can achieve a higher pitching angle.

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