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Journal articles on the topic 'Aerospike Nozzle'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Lai, A., S. S. Wei, C. H. Lai, J. L. Chen, Y. H. Liao, J. S. Wu, and Y. S. Chen. "Comparison of the Propulsion Performance of Aerospike and Bell-Shaped Nozzle Using Hydrogen Peroxide Monopropellant Under Sea-Level Condition." Journal of Mechanics 35, no. 3 (July 2, 2018): 427–40. http://dx.doi.org/10.1017/jmech.2018.18.

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ABSTRACTThis study investigates numerically the performance of applying aerospike nozzle in a hydrogen peroxide mono-propellant propulsion system. A set of governing equations, including continuity, momentum, energy and species conservation equations with extended k-ε turbulence equations, are solved using the finite-volume method. The hydrogen peroxide mono-propellant is assumed to be fully decomposed into water vapor and oxygen after flowing through a catalyst bed before entering the nozzle. The aerospike nozzle is expected to have high performance even in deep throttling cases due to its self-compensating characteristics in a wide range of ambient pressure environments. The results show that the thrust coefficient efficiency (Cf,η) of this work exceeds 90% of the theoretical value with a nozzle pressure ratio (PR) in the range of 20 ~ 45. Many complex gas dynamics phenomena in the aerospike nozzle are found and explained in the paper. In addition, performance of the aerospike nozzle is compared with that of the bell-shape nozzle.

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2

Menon, Pranav. "Investigation of Variation in the Performance of an Electro Thermal Thruster with Aerospike Nozzle." Advanced Engineering Forum 16 (April 2016): 91–103. http://dx.doi.org/10.4028/www.scientific.net/aef.16.91.

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One of the most recently developed modes of propulsion is electric propulsion. The commonly used chemical propulsion systems have the advantage of a high Specific Impulse as compared to that of ion propulsion systems. However, owing to the efficacy of ion propulsion systems, it is considered the future of space exploration.Electro thermal thrusters produce thrust by using electrical fields to force hot plasma out of the nozzle with certain exit velocity. The plasma’s exit velocity and the system’s thrust capacity, as of now, are insufficient for space travel to be conducted within a reasonable time. I intend to study the possibility of improving the thruster’s performance by using an aerospike nozzle as an exit nozzle which meets the conditions required for the thruster to function appropriately. I shall be studying the plasma plume exit velocity variation with respect to the nozzles used. Also, a thermal analysis will be conducted in order to find the correct material for the nozzle.

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3

Korte, J. J., A. O. Salas, H. J. Dunn, N. M. Alexandrov, W. W. Follett, G. E. Orient, and A. H. Hadid. "Multidisciplinary Approach to Linear Aerospike Nozzle Design." Journal of Propulsion and Power 17, no. 1 (January 2001): 93–98. http://dx.doi.org/10.2514/2.5712.

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4

Bogoi, Alina, Radu D. Rugescu, Valentin Ionut Misirliu, Florin Radu Bacaran, and Mihai Predoiu. "Inviscid Nozzle for Aerospike Rocket Engine Application." Applied Mechanics and Materials 811 (November 2015): 152–56. http://dx.doi.org/10.4028/www.scientific.net/amm.811.152.

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A computational method for the steady 2-D flow in axially symmetrical rocket nozzles with a given profile is developed, in order to determine the Maximum thrust contour of rocket engine nozzles with large expansion ratio. The optimized nozzles proved a more than 10% increase in the integral specific impulse recorded during the variable altitude atmospheric flight of rocket vehicles. The method is well suited for application in the design of the optimum contour for axially-symmetric nozzles for atmospheric rocket ascent, specifically for aerospike type nozzles, as for other similar industrial applications in gas and steam turbine technology.

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5

., Vinay Kumar Levaka. "DESIGN AND FLOW SIMULATION OF TRUNCATED AEROSPIKE NOZZLE." International Journal of Research in Engineering and Technology 03, no. 11 (November 25, 2014): 122–31. http://dx.doi.org/10.15623/ijret.2014.0311019.

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6

Naveen Kumar, K., M. Gopalsamy, Daniel Antony, R. Krishnaraj, and Chaparala B. V. Viswanadh. "Design and Optimization of Aerospike nozzle using CFD." IOP Conference Series: Materials Science and Engineering 247 (October 2017): 012008. http://dx.doi.org/10.1088/1757-899x/247/1/012008.

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7

Wang, Chang-Hui, Yu Liu, and Li-Zi Qin. "Aerospike nozzle contour design and its performance validation." Acta Astronautica 64, no. 11-12 (June 2009): 1264–75. http://dx.doi.org/10.1016/j.actaastro.2008.01.045.

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8

Chaudhari, Krunal C. "Analysis of Aerospike Nozzle Structural Contour Design Performance Optimization." International Journal for Research in Applied Science and Engineering Technology V, no. X (October 23, 2017): 1000–1004. http://dx.doi.org/10.22214/ijraset.2017.10144.

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9

Sankari Ashok Alshiya, K., M. Santhosh, V. K. Santhosh, and S. Sai Gopal. "Experimental analysis of jet flow in an aerospike nozzle." Materials Today: Proceedings 46 (2021): 3444–50. http://dx.doi.org/10.1016/j.matpr.2020.11.783.

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10

Ferlauto, Michele, Andrea Ferrero, Matteo Marsicovetere, and Roberto Marsilio. "Differential Throttling and Fluidic Thrust Vectoring in a Linear Aerospike." International Journal of Turbomachinery, Propulsion and Power 6, no. 2 (April 21, 2021): 8. http://dx.doi.org/10.3390/ijtpp6020008.

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Aerospike nozzles represent an interesting solution for Single-Stage-To-Orbit or clustered launchers owing to their self-adapting capability, which can lead to better performance compared to classical nozzles. Furthermore, they can provide thrust vectoring in several ways. A simple solution consists of applying differential throttling when multiple combustion chambers are used. An alternative solution is represented by fluidic thrust vectoring, which requires the injection of a secondary flow from a slot. In this work, the flow field in a linear aerospike nozzle was investigated numerically and both differential throttling and fluidic thrust vectoring were studied. The flow field was predicted by solving the Reynolds-averaged Navier–Stokes equations. The thrust vectoring performance was evaluated in terms of side force generation and axial force reduction. The effectiveness of fluidic thrust vectoring was investigated by changing the mass flow rate of secondary flow and injection location. The results show that the response of the system can be non-monotone with respect to the mass flow rate of the secondary injection. In contrast, differential throttling provides a linear behaviour but it can only be applied to configurations with multiple combustion chambers. Finally, the effects of different plug truncation levels are discussed.

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11

Takahashi, Hidemi. "Practical Approach for Absolute Density Field Measurement Using Background-Oriented Schlieren." Aerospace 5, no. 4 (December 17, 2018): 129. http://dx.doi.org/10.3390/aerospace5040129.

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A practical approach for deriving the absolute density field based on the background-oriented schlieren method in a high-speed flowfield was implemented. The flowfield of interest was a two-dimensional compressible flowfield created by two supersonic streams to simulate a linear aerospike nozzle operated under a supersonic in-flight condition. The linear aerospike nozzle had a two-dimensional cell nozzle with a design Mach number of 3.5, followed by a spike nozzle. The external flow simulating the in-flight condition was 2.0. The wall density distribution used as the wall boundary condition for Poisson’s equation to solve the density field was derived by a simplified isentropic assumption based on the measured wall pressure distribution, and its validity was evaluated by comparing with that predicted by numerical simulation. Unknown coefficients in Poisson’s equation were determined by comparing the wall density distribution with that predicted by the model. By comparing the derived density field based on the background-oriented schlieren method to that predicted by the model and numerical simulation, the absolute density field was derived within an error of 10% on the wall distribution. This practical approach using a simplified isentropic assumption based on measured pressure distribution thus provided density distribution with sufficient accuracy.

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12

Eilers, Shannon D., Matthew D. Wilson, Stephen A. Whitmore, and Zachary W. Peterson. "Side-Force Amplification on an Aerodynamically Thrust-Vectored Aerospike Nozzle." Journal of Propulsion and Power 28, no. 4 (July 2012): 811–19. http://dx.doi.org/10.2514/1.b34381.

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13

Udaiyakumar, K. C., Kartik Venkataramani Iyer, V. Akhil, Anshul Motwani, and Vibhor Rajesh Bhaise. "Numerical Simulation and Contour Design of Aerospike Nozzle: a Behavioural Study on Truncation Effects of Nozzle." International Review of Aerospace Engineering (IREASE) 13, no. 4 (August 31, 2020): 141. http://dx.doi.org/10.15866/irease.v13i4.17343.

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14

Simmons, J., and Richard Branam. "Parametric Study of Dual-Expander Aerospike Nozzle Upper-Stage Rocket Engine." Journal of Spacecraft and Rockets 48, no. 2 (March 2011): 355–67. http://dx.doi.org/10.2514/1.51534.

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15

Verma, S. B. "Performance Characteristics of an Annular Conical Aerospike Nozzle with Freestream Effect." Journal of Propulsion and Power 25, no. 3 (May 2009): 783–91. http://dx.doi.org/10.2514/1.40302.

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16

Balaji, G., B. Navin Kumar, J. Vijayarangam, A. Vasudevan, and R. Pandiyarajan. "Numerical investigation of expansion Fan optimization of truncated annular aerospike nozzle." Materials Today: Proceedings 46 (2021): 4283–88. http://dx.doi.org/10.1016/j.matpr.2021.03.124.

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17

SHIBAO, Masafumi, Nobuyuki TSUBOI, and Takashi ITO. "808 Numerical Analysis of the Aerospike Nozzle for the Evaluation of Performance : Effect of Inner Nozzle Configuration." Proceedings of Conference of Kyushu Branch 2014.67 (2014): _808–1_—_808–2_. http://dx.doi.org/10.1299/jsmekyushu.2014.67._808-1_.

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18

MORI, Hideo, Hiroki YAMAGUCHI, Atsushi FUKUSHIMA, Masateru FUTAMURA, and Tomohide NIIMI. "Sidewall Shape Optimization for Linear Aerospike Nozzle using NO-LIF and PSP." Journal of the Visualization Society of Japan 27, Supplement2 (2007): 185–86. http://dx.doi.org/10.3154/jvs.27.supplement2_185.

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19

Rajesh, G., Gyanesh Kumar, H. D. Kim, and Mathew George. "Computational and Experimental Simulations of the Flow Characteristics of an Aerospike Nozzle." Journal of the Korean Society of Visualization 10, no. 1 (April 30, 2012): 47–54. http://dx.doi.org/10.5407/jksv.2011.10.1.047.

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20

Tian, Hui, Zihao Guo, Zhu Hao, Liu Hedong, and Chengen Li. "Numerical and experimental investigation of throttleable hybrid rocket motor with aerospike nozzle." Aerospace Science and Technology 106 (November 2020): 105983. http://dx.doi.org/10.1016/j.ast.2020.105983.

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21

Noori, S., and A. Shahrokhi. "The Influence of Different Turbulence Models on the FlowField Characteristics of an Aerospike Nozzle." Applied Mechanics and Materials 110-116 (October 2011): 437–43. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.437.

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To improve the calculation of the flow properties of an aerospike nozzle, different turbulent models are studied in this research. The primary shape of the nozzle and the plug is determined through utilizing an approximate method. The flow field is then simulated using Navier-Stokes equations for compressible flow. The computational methodology utilizes steady state density-based formulation and a finite volume cell centered scheme to discretize the flow field equations. To accelerate the solution convergence, the flow field is divided into several zones. Each zone is facilitated with proper unstructured grid and appropriate initial conditions are implemented to each zone. The accuracy and the robustness of wall function based turbulence models i.e. standard and RNG k-ε models are compared with those of Spalart-Allmaras (S-A) and k-ω turbulence models.

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22

TANIGUCHI, Mashio, Hideo MORI, Ryutaro NISHIHIRA, Atsushi FUKUSHIMA, and Tomohide NIIMI. "Investigation of Linear-Type Aerospike Nozzle with Sidewalls using NO-LIF and PSP." Journal of the Visualization Society of Japan 25, Supplement1 (2005): 335–38. http://dx.doi.org/10.3154/jvs.25.supplement1_335.

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23

Niimi, Tomohide, Hideo Mori, Kazuki Okabe, Yusuke Masai, and Mashio Taniguchi. "Visualization and Analyses of Jet Structures from a Cluster-Type Linear Aerospike Nozzle." JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 52, no. 605 (2004): 235–40. http://dx.doi.org/10.2322/jjsass.52.235.

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24

Karthikeyan, T., S. K. Aravindhkumar, and J. Arun Kumar. "Design and Analysis of Aerospike Nozzle to Improve Thrust in Hybrid Rocket Engine." International Journal of Engineering Trends and Technology 36, no. 7 (June 25, 2016): 347–51. http://dx.doi.org/10.14445/22315381/ijett-v36p265.

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25

Swathi, Gorle, Chaganti Satya Sandeep, Mandapudi Snigdha, Gudikandula Sravanthi, and Dussa Govardhan. "Three Dimensional Computational Flow Simulation of Truncated Aerospike Nozzle Considering Different Plug Lengths." Indian Journal of Science and Technology 10, no. 13 (April 1, 2017): 1–4. http://dx.doi.org/10.17485/ijst/2017/v10i13/111909.

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26

Cheah, Kean How, and Jit Kai Chin. "DESIGN AND FABRICATION OF MICRONOZZLES." IIUM Engineering Journal 12, no. 1 (May 17, 2011): 51–62. http://dx.doi.org/10.31436/iiumej.v12i1.65.

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Micronozzle, a key component in micropropulsion system, has been designed and fabricated. Quasi 1D inviscid theory was used in designing a series of conical micronozzles of different expander half-angles (10Â°-50Â°). Aerospike micronozzle, a promising candidate to achieve high performance propulsion system, was designed with Angelino method (or Approximate method). Both micronozzles were fabricated using soft lithography, an inexpensive and relatively simple technique comparing to well-established deep reactive ion etching (DRIE) technique, with polydimethylsiloxane (PDMS) as structural material. Micronozzles with two different nozzle throat width, 53.5Âµm and 107Âµm, were fabricated for comparison. Microscopic inspections reveal 107Âµm is the more producible nozzle throat width with current equipments. The PDMS-based micronozzle can be used as cold gas microthruster system for micro- and nanosatellites.

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27

NARIMIYA, Tadashi, Nobuyuki TSUBOI, and Takashi ITO. "811 Numerical analysis of the aerospike nozzle flow fields for the evaluation of performance." Proceedings of Conference of Kyushu Branch 2012.65 (2012): 287–88. http://dx.doi.org/10.1299/jsmekyushu.2012.65.287.

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28

Ito, Takashi, and Kozo Fujii. "Flow Field and Performance Analysis of an Annular-Type Aerospike Nozzle with Base Bleeding." TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 46, no. 151 (2003): 17–23. http://dx.doi.org/10.2322/tjsass.46.17.

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29

He, Miaosheng, Lizi Qin, and Yu Liu. "Numerical investigation of flow separation behavior in an over-expanded annular conical aerospike nozzle." Chinese Journal of Aeronautics 28, no. 4 (August 2015): 983–1002. http://dx.doi.org/10.1016/j.cja.2015.06.016.

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30

NIIMI, Tomohide, Hideo MORI, Mashio TANIGUCHI, and Ryutaro NISHIHIRA. "Experimental Analyses of Jet Structures around Clustered Linear Aerospike Nozzle by NO-LIF and PSP." Journal of the Visualization Society of Japan 24, Supplement1 (2004): 155–56. http://dx.doi.org/10.3154/jvs.24.supplement1_155.

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31

TANIGUCHI, Mashio, Hideo MORI, Ryutaro NISHIHIRA, and Tomohide NIIMI. "Experimental Analyses of Jet Structures around Clustered Linear Aerospike Nozzle by NO-LIF and PSP." Transaction of the Visualization Society of Japan 26, no. 2 (2006): 13–18. http://dx.doi.org/10.3154/tvsj.26.13.

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32

TANIGUCHI, Mashio, Hideo MORI, Ryutaro NISHIHIRA, and Tomohide NIIMI. "Experimental Investigation of Sidewall-Effect on Linear-Type Aerospike Nozzle using NO-LIF and PSP." Transaction of the Visualization Society of Japan 26, no. 10 (2006): 97–104. http://dx.doi.org/10.3154/tvsj.26.97.

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33

Jourdaine, Nicolas, Nobuyuki Tsuboi, Kohei Ozawa, Takayuki Kojima, and A. Koichi Hayashi. "Three-dimensional numerical thrust performance analysis of hydrogen fuel mixture rotating detonation engine with aerospike nozzle." Proceedings of the Combustion Institute 37, no. 3 (2019): 3443–51. http://dx.doi.org/10.1016/j.proci.2018.09.024.

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34

TANIGUCHI, Mashio, Hideo MORI, Ryutaro NISHIHIRA, and Tomohide NIIMI. "Experimental Analyses of Flow Field around Linear-Type Aerospike Nozzle with Sidewall by NO-LIF and PSP." Proceedings of the Fluids engineering conference 2004 (2004): 311. http://dx.doi.org/10.1299/jsmefed.2004.311.

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35

Huang, Yue, Hanqing Xia, Xiaonan Chen, Zhenye Luan, and Yancheng You. "Shock dynamics and expansion characteristics of an aerospike nozzle and its interaction with the rotating detonation combustor." Aerospace Science and Technology 117 (October 2021): 106969. http://dx.doi.org/10.1016/j.ast.2021.106969.

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36

Ashley, Steven. "Bringing Launch Costs Down to Earth." Mechanical Engineering 120, no. 10 (October 1, 1998): 62–68. http://dx.doi.org/10.1115/1.1998-oct-1.

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This article discusses the three federally funded projects that are underway to develop new rocket engines that can make it more affordable to send payloads into orbits. The new RS-68 propulsion system is Rocketdyne's entry in competition to power the US Air Force's new heavy-lift booster. The most ambitious of the new propulsion system designs is Rocketdyne's XRS-2200 linear aerospike engine, a seemingly nozzle-less oxygen/hydrogen powerplant that is designed to send the autonomously controlled NASA X-33 lifting body into orbit. The X-33 is being developed by Lockheed Martin Skunk Works, Palmdale, CA. The key for new launch vehicles, whether they're expendable or reusable, is to get the costs down. The article also highlights that the payload that can be lofted by a launch vehicle depends in large part on engine performance and the ratio of propellant to structural weight. Bell nozzles are designed to offer the best compromise of shape and length for a vehicle and flight path. Rocketdyne's R-68 engine is to be 17 feet tall and 8 feet wide at the base. The key to the R-68 engine design was the selection of hydrogen as the propellant rather than kerosene.

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37

Hamaidia, Walid, Toufik Zebbiche, Mohamed Sellam, and Abderrazak Allali. "Performance improvement of supersonic nozzles design using a high-temperature model." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 13 (February 27, 2019): 4895–910. http://dx.doi.org/10.1177/0954410019831862.

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The aim of this paper is to discuss the development of new contours of axisymmetric supersonic nozzles giving a uniform and parallel flow at the exit section, to improve the aerodynamic performances compared to the minimum length nozzle, by increasing the exit Mach number and the thrust coefficient, and by reduction of the nozzle's mass, while holding the same throat section between the two nozzles. The new nozzle is named the best performance nozzle. Its form contains a cylindrical central body and an external wall for the flow redress. The study is done at high temperature, lower than the dissociation threshold of the molecules. The variation of the specific heats with the temperature is considered. The design is made by the method of characteristics. The predictor-corrector algorithm is used to make the numerical resolution of the obtained nonlinear algebraic equations. The validation of results is made by the convergence of the numerical critical sections ratio with that given by the theory. The comparison of the results is made with the minimum length nozzle since it is currently used in the aerospace propulsion. The design depends on M E, T0, y body, y*, and the mesh generation. The application is done with air. A computational fluid dynamics verification for the under nozzle expressed regime has shown that a flow separation with the wall is observed because of the side-loads, which are reduced for this new nozzle compared to the minimum length nozzle.

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38

A.K., Mubarak, and Tide P.S. "Design of a double parabolic supersonic nozzle and performance evaluation by experimental and numerical methods." Aircraft Engineering and Aerospace Technology 91, no. 1 (January 7, 2018): 145–56. http://dx.doi.org/10.1108/aeat-12-2017-0275.

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Purpose The purpose of this paper is to design a double parabolic nozzle and to compare the performance with conventional nozzle designs. Design/methodology/approach The throat diameter and divergent length for Conical, Bell and Double Parabolic nozzles were kept same for the sake of comparison. The double parabolic nozzle has been designed in such a way that the maximum slope of the divergent curve is taken as one-third of the Prandtl Meyer (PM) angle. The studies were carried out at Nozzle Pressure Ratio (NPR) of 5 and also at design conditions (NPR = 3.7). Experimental measurements were carried out for all the three nozzle configurations and the performance parameters compared. Numerical simulations were also carried out in a two-dimensional computational domain incorporating density-based solver with RANS equations and SST k-ω turbulence model. Findings The numerical predictions were found to be in reasonable agreement with the measured experimental values. An enhancement in thrust was observed for double parabolic nozzle when compared with that of conical and bell nozzles. Research limitations/implications Even though the present numerical simulations were capable of predicting shock cell parameters reasonably well, shock oscillations were not captured. Practical implications The double parabolic nozzle design has enormous practical importance as a small increase in thrust can result in a significant gain in pay load. Social implications The thrust developed by the double parabolic nozzle is seen to be on the higher side than that of conventional nozzles with better fuel economy. Originality/value The overall performance of the double parabolic nozzle is better than conical and bell nozzles for the same throat diameter and length.

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39

V. Paul, Roy, Kriparaj K.G., and Tide P.S. "Numerical predictions of the flow characteristics of subsonic jet emanating from corrugated lobed nozzle." Aircraft Engineering and Aerospace Technology 92, no. 7 (May 4, 2020): 955–72. http://dx.doi.org/10.1108/aeat-03-2019-0041.

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Purpose The purpose of this study is to investigate the aerodynamic characteristics of subsonic jet emanating from corrugated lobed nozzle. Design/methodology/approach Numerical simulations of subsonic turbulent jets from corrugated lobed nozzles using shear stress transport k-ω turbulence model have been carried out. The analysis was carried out by varying parameters such as lobe length, lobe penetration and lobe count at a Mach number of 0.75. The numerical predictions of axial and radial variation of the mean axial velocity, u′u′ ¯ and v′v′ ¯ have been compared with experimental results of conventional round and chevron nozzles reported in the literature. Findings The centreline velocity at the exit of the corrugated lobed nozzle was found to be lower than the velocity at the outer edges of the nozzle. The predicted potential core length is lesser than the experimental results of the conventional round nozzle and hence the decay in centreline velocity is faster. The centreline velocity increases with the increase in lobe length and becomes more uniform at the exit. The potential core length increases with the increase in lobe count and decreases with the increase in lobe penetration. The turbulent kinetic energy region is narrower with early appearance of a stronger peak for higher lobe penetration. The centreline velocity degrades much faster in the corrugated nozzle than the chevron nozzle and the peak value of Reynolds stress appears in the vicinity of the nozzle exit. Practical implications The corrugated lobed nozzles are used for enhancing mixing without the thrust penalty inducing better acoustic benefits. Originality/value The prominent features of the corrugated lobed nozzle were obtained from the extensive study of variation of flow characteristics for different lobe parameters after making comparison with round and chevron nozzle, which paved the way to the utilization of these nozzles for various applications.

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40

Elangovan, S., and E. Rathakrishnan. "Studies on high speed jets from nozzles with internal grooves." Aeronautical Journal 108, no. 1079 (January 2004): 43–50. http://dx.doi.org/10.1017/s000192400000498x.

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Experiments were carried out on jets issuing from circular nozzles with grooved exits and the results compared with those of the plain nozzle. The plain nozzle had an exit diameter of 10mm. Because of the introduction of semi-circular grooves at the exit, the effective or equivalent diameter of the grooved nozzles was 10·44mm. The groove lengths were varied as 3, 5 and 8mm. The nozzles were operated at fully expanded sonic and underexpanded exit conditions. The corresponding fully expanded Mach numbers were 1·0 and 1·41. The shock cell structure of the underexpanded jets from grooved nozzles appeared to be weaker than that of the plain nozzle, as indicated by lesser amplitudes of the cyclic variation of the Pitot pressure. The iso-Mach contours indicate that the jet spread along the grooved plane is significantly higher than that along the ungrooved plane. Off-centre peaks were observed in the mean pressure profile of underexpanded jets from grooved nozzles. They were probably due to the streamwise vortices shed from the grooves.

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41

Dong, Pengbo, Keiya Nishida, and Youichi Ogata. "Characterization of multi-hole nozzle sprays and internal flow for different nozzle hole lengths in direct-injection diesel engines." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, no. 4 (August 5, 2016): 500–515. http://dx.doi.org/10.1177/0954407016653890.

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Multi-hole nozzles have a wide range of application in the fuel supply system of modern diesel engines, although single-hole nozzles dominate basic internal flow and spray research. The parameters of the nozzle geometry are crucial factors that can alter the internal flow dynamics of the nozzle and the consequent spray behaviours. The novelty of this study lies in implementing the application of practical prototype mini-sac multi-hole diesel nozzles to experimental and numerical studies. The internal flow and spray characteristics generated by practical multi-hole (10-hole) nozzles with different sac wall thicknesses (0.4 mm, 0.6 mm and 0.8 mm) were investigated in conjunction with a series of experimental and computational methods using a constant injection quantity (2 mm3/hole). Globally, the analysis mainly concentrated on different nozzle flow dynamics, different injection processes and different spray morphologies. Specifically, the high-speed video observation method was applied to visualize the injection processes and the spray evolution of different nozzles inside a high-pressure vessel. Furthermore, numerical simulations were conducted to reveal the three-dimensional nature of the internal flow inside different configurations; this was instructive in helping us to understand better the mechanism behind the spray behaviours. The results indicate that intense cavitating, turbulent and spiral rotating flow patterns occur inside practical multi-hole nozzles, and the consequent sprays emerging from the nozzles are perturbed, asymmetrical and unstable in both the near field and the far field. Moreover, a decrease in the nozzle hole length can increase the effects of cavitation, turbulence, the void fraction and the axial and radial injection velocity components on the nozzle hole exit; this is accompanied by an intriguing longer injection duration, wider near-field and far-field spray widths, a lower injection rate, and overlapping or even shorter spray propagation. However, these changes are not linear, and different parameters have different sensitivities to the variation in the nozzle hole length.

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42

Shan, Yong, Xiaoming Zhou, Xiaoming Tan, Jingzhou Zhang, and Yanhua Wu. "Parametric Design Method and Performance Analysis of Double S-Shaped Nozzles." International Journal of Aerospace Engineering 2019 (May 12, 2019): 1–24. http://dx.doi.org/10.1155/2019/4694837.

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A parametric design method, which was based on super-elliptical transition and self-adaption infrared radiation shield for the double S-shaped nozzle, was introduced. The complete shielding of high-temperature components in the S-shaped nozzle was realized. Model experiments and numerical simulations were performed to investigate the effects of offset ratio S/D, the ratio of length to diameter L/D, and the aspect ratio W/H on the aerodynamics and infrared radiation. The results showed that the total pressure recovery and thrust coefficients were improved initially, but dropped rapidly with the increase in offset ratios with the range of investigated parameters. There existed an optimal offset ratio for the aerodynamic performances. Considering the weight penalty, the length of nozzles should only be increased properly to achieve better aerodynamic performances. Both friction and viscous losses caused by large streamwise vortices dominated the aerodynamic performances of nozzles. The nozzle with the aspect ratio of W/H=5.0 was recommended for achieving optimal aerodynamics. The increase in aspect and offset ratios could effectively suppress plume radiation, which was, however, not sensitive to overall radiation. Compared to circular nozzles, double S-shaped nozzles reduced overall infrared radiation by over 50%, which proves significant stealth ability. A balance between aerodynamic performances and infrared radiation suppression could be reached for double S-shaped nozzles.

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Salvador, Francisco J., Joaquin de la Morena, Marcos Carreres, and David Jaramillo. "Numerical analysis of flow characteristics in diesel injector nozzles with convergent-divergent orifices." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, no. 14 (February 1, 2017): 1935–44. http://dx.doi.org/10.1177/0954407017692220.

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The geometry of diesel injector nozzles is known to significantly affect the characteristic spray behavior and emissions formation. In this paper, a novel nozzle concept, consisting of orifices with a convergent–divergent shape, is investigated through Computational Fluid Dynamics techniques. Three of these nozzles, characterized by different degrees of conicity, are compared to a nozzle with cylindrical orifices, which acts as a baseline. A homogeneous equilibrium model, validated against experimental data in previous works by the authors, is used to calculate the eventual cavitation formation inside these orifices. Additionally, the characteristics of the flow at the orifice outlet are analyzed for the four aforementioned nozzles in terms of their steady-state mass flow, effective outlet velocity and area coefficient. The results show that convergent-divergent nozzles exhibit a high cavitation intensity, located in the transition between the convergent and the divergent sections. This high cavitation intensity tends to compensate for the expected velocity decrease induced by the divergent shape, producing effective velocity values similar to those achieved by the cylindrical nozzle in many of the simulated conditions. The characteristics of the flow, together with the higher spray opening angles expected due to the divergent section of the nozzle, may improve atomization and fuel-air mixing processes.

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Schuckert, Sebastian, Oliver Hofmann, and Georg Wachtmeister. "Experimental investigation into simulated aging effects of common-rail injector nozzles: Influences on injection rate, spray characteristics, and engine performance." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 2-3 (June 11, 2019): 349–62. http://dx.doi.org/10.1177/0954407019855289.

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Emission performance of combustion engines has gained outstanding importance with both legislators and customers over the past years. Injector aging, such as nozzle wear or coking, results in the deterioration of injection and emission parameters. In this study, the influences of aging effects on injection rate, fuel spray as well as engine performance and emissions were assessed. Nozzles, which had previously been operated in a vehicle engine and were likely to have suffered from aging, showed no aging-induced characteristics during injection rate and spray measurements and were not investigated further. Therefore, nozzles with different nozzle hole diameters were utilized to simulate the different aging effects. Injection rate measurements demonstrated, that for smaller energizing times, a nozzle with smaller nozzle holes can deliver a higher injected mass than a nozzle with bigger nozzle holes. The adaptation of energizing time or injection pressure demonstrated the potential to compensate the change in engine load due to smaller or bigger nozzle holes. For bigger nozzle holes, the adaptation of injection pressure in order to restore the target load returned lower NOx emissions, whereas the adaptation of the energizing time always yielded lower soot emissions compared to the reference nozzle. For small nozzle holes, the optimization of the start of energizing reduced specific NOx emissions without increasing specific soot emissions. The comparison of measured injection rate and fuel spray characteristics to the ones reported in literature confirms the possibility of simulating nozzle wear by increased nozzle holes and coking by smaller nozzle holes. The results of this study are of vital interest to the research of aging effects and add useful knowledge about compensation methods for nozzle aging.

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B.T., Kannan, and Panchapakesan N.R. "Effect of momentum flux distribution on multiple round jets." Aircraft Engineering and Aerospace Technology 90, no. 2 (March 5, 2018): 452–60. http://dx.doi.org/10.1108/aeat-11-2016-0233.

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Purpose This study aims to investigate the effects of nozzle momentum flux distribution on the flow field characteristics. Design/methodology/approach The nozzle configuration consists of a central nozzle surrounded by four nozzles. All nozzles have the same diameter and constant separation between nozzles. OpenFOAM® is used for simulating the jet flow. Reynolds-averaged Navier-Stokes (RANS) equations are solved iteratively with a first-order closure for turbulence. Pitot-static tube with differential pressure transducer is used for mean velocity measurements. The comparison of computed results with experimental data shows similar trend and acceptable validation. Findings According to the results, the momentum flux distribution significantly alters the near field of multiple turbulent round jets. Highly non-linear decay region in the near field is found for the cases having higher momentum in the outer jets. As a result of merging, increased positive pressure is found in the mixing region. Higher secondary flows and wider mixing region are reported as a result of momentum transfer from axial to lateral directions by Reynolds stresses. Research limitations/implications The present study is limited to isothermal flow of air jet in air medium. Social implications Optimum momentum flux distribution in multijet injector of a combustor can reap better mixing leading to better efficiency and lesser environmental pollution. Originality/value As summary, the contributions of this paper in the field of turbulent jets are following: simulations for various momentum distribution cases have been performed. In all the cases, the flow at the nozzle exit is subsonic along with constant velocity profile. To simulate proper flow field, a large cylinder-type domain with structured grid is used with refinements toward the nozzle exit and jet axis. The results show that the non-linearity increases with increase in momentum of outer jets. Longer merging zones are reported for cases with higher momentum in outer nozzles using area-averaged turbulent kinetic energy. Similarly, wider mixing regions are reported using secondary flow parameter and visualizations.

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Dix, J., A. J. Saddington, K. Knowles, and M. A. Richardson. "Infra-red signature reduction study on a small-scale jet engine." Aeronautical Journal 109, no. 1092 (February 2005): 83–88. http://dx.doi.org/10.1017/s0001924000000580.

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Abstract This paper presents infra-red signature data for a small-scale, low pressure ratio turbojet engine typical of that used in unmanned air vehicle applications. The aim of the study was to test a number of different convergent nozzle designs concentrating on those with trailing edge modifications. The engine used in the tests has a single stage centrifugal compressor and radial inflow turbine and is designed to produce approximately 150N of thrust at 103,500rpm using liquid propane fuel. The test rig consisted of a calibrated thrust stand whilst the engine was controlled through an electronic engine control unit and laptop PC. The jet plume was visualised using an infra-red spectroradiometer which yielded qualitative data across the infra-red spectrum. Simultaneous measurements were also made of the engine thrust. A Pitot probe was used to take pressure readings across different sections of the exhaust flow. Analysis of the infrared signature of the engine exhaust plume and any thrust penalty yielded a performance comparison for each of the nozzles tested. Correlation of engine thrust with engine rpm showed that, within the accuracy of the measurements, there was no significant thrust penalty associated with the notched nozzles. Infra-red imagery of the plain and 60° notched nozzles indicated that the latter reduced the length of the hottest part of the exhaust plume by approximately 33%. The spectroradiometer data shows a significant reduction in spectral radiance for the CO2 wavelength of approximately 4·3µm when the notched nozzles are used. The 60° notched nozzle appeared to perform best in reducing the spectral radiance at this wavelength. Centreline total pressure measurements in the exhaust plume correlated well with the infra-red imagery in that a potential core length reduction of up to 30% could be achieved using the 60° notched nozzle. Total pressure contours recorded 20mm (0·43D) downstream of the nozzle exit plane suggest that the notched nozzles are promoting increased mixing through radial spreading of the jet possibly associated with increased streamwise vorticity (although the latter could not be confirmed). There were also signs that the jet plumes being investigated were swirling.

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Bhide, Kalyani, Kiran Siddappaji, and Shaaban Abdallah. "Aspect Ratio Driven Relationship between Nozzle Internal Flow and Supersonic Jet Mixing." Aerospace 8, no. 3 (March 16, 2021): 78. http://dx.doi.org/10.3390/aerospace8030078.

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This work attempts to connect internal flow to the exit flow and supersonic jet mixing in rectangular nozzles with low to high aspect ratios (AR). A series of low and high aspect ratio rectangular nozzles (design Mach number = 1.5) with sharp throats are numerically investigated using steady state Reynolds-averaged Navier−Stokes (RANS) computational fluid dynamics (CFD) with k-omega shear stress transport (SST) turbulence model. The numerical shadowgraph reveals stronger shocks at low ARs which become weaker with increasing AR due to less flow turning at the throat. Stronger shocks cause more aggressive gradients in the boundary layer resulting in higher wall shear stresses at the throat for low ARs. The boundary layer becomes thick at low ARs creating more aerodynamic blockage. The boundary layer exiting the nozzle transforms into a shear layer and grows thicker in the high AR nozzle with a smaller potential core length. The variation in the boundary layer growth on the minor and major axis is explained and its growth downstream the throat has a significant role in nozzle exit flow characteristics. The loss mechanism throughout the flow is shown as the entropy generated due to viscous dissipation and accounts for supersonic jet mixing. Axis switching phenomenon is also addressed by analyzing the streamwise vorticity fields at various locations downstream from the nozzle exit.

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Bermúdez, V., R. Payri, F. J. Salvador, and A. H. Plazas. "Study of the influence of nozzle seat type on injection rate and spray behaviour." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 219, no. 5 (May 1, 2005): 677–89. http://dx.doi.org/10.1243/095440705x28303.

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A deep analysis of the injection rate characteristics and spray behaviour of the most used nozzle types in diesel engines [microSAC and valve covered orifice (VCO)] has been carried out. In order to compare the injection characteristics and the spray behaviour of both nozzle types, several experimental installations were used, such as the steady flow test rig, injection rate test rig, spray momentum test rig, and nitrogen test rig, to obtain a full hydrodynamic and spray characterization. The study of the flow in both nozzles was analysed under steady flow conditions in the steady flow test rig and in real unsteady flow conditions in the injection rate test rig and the spray momentum test rig. The macroscopic properties of the spray (tip penetration and spray cone angle) were characterized using a high-pressure test rig. From the point of view of the internal flow behaviour, the results showed interesting differences in the permeability of both nozzle geometries, with a higher discharge coefficient in the microSAC nozzle. However, from the point of view of air entrainment, the results showed a better quality of fuel-air mixing in the VCO nozzle. Besides the evidence from the experimental results, a theoretical analysis was carried out in order to identify the most important parameters that determine the spray behaviour and thus justify the different macroscopic behaviour of both nozzles.

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Laitón, Sergio Nicolas Pachón, João Felipe de Araujo Martos, Israel da Silveira Rego, George Santos Marinho, and Paulo Gilberto de Paula Toro. "Experimental Study of Single Expansion Ramp Nozzle Performance Using Pitot Pressure and Static Pressure Measurements." International Journal of Aerospace Engineering 2019 (February 27, 2019): 1–11. http://dx.doi.org/10.1155/2019/7478129.

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In order to overcome the drag at hypersonic speed, hypersonic flight vehicles require a high level of integration between the airframe and the propulsion system. Propulsion system based on scramjet engine needs a close interaction between its aerodynamics and stability. Hypersonic vehicle nozzles which are responsible for generating most of the thrust generally are fused with the vehicle afterbody influencing the thrust efficiency and vehicle stability. Single expansion ramp nozzles (SERN) produce enough thrust necessary to hypersonic flight and are the subject of analysis of this work. Flow expansion within a nozzle is naturally 3D phenomena; however, the use of side walls controls the expansion approximating it to a 2D flow confined. An experimental study of nozzle performance traditionally uses the stagnation conditions and the area ratio of the diverging section of the tunnel for approaching the combustor exit conditions. In this work, a complete hypersonic vehicle based on scramjet propulsion is installed in the test section of a hypersonic shock tunnel. Therefore, the SERN inlet conditions are the real conditions from the combustor exit. The performance of a SERN is evaluated experimentally under real conditions obtained from the combustor exit. To quantify the SERN performance parameters such as thrust, axial thrust coefficient Cfx and lift L are investigated and evaluated. The generated thrust was determined from both static and pitot pressure measurements considering the installation of side walls to approximate 2D flow. Measurements obtained by a rake show that the flow at the nozzle exit is not symmetric. Pitot and pressure measurements inside the combustion chamber show nonuniform flow condition as expected due to side wall compression and boundary layer. The total axial thrust for the nozzle obtained with the side wall is slightly higher than without it. Static pressure measurements at the centerline of the nozzle show that the residence time of the flow in the expansion section is short enough and the flow of the central region of the nozzle is not altered by the lateral expansion when nozzle configuration does not include side walls.

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Li, Shangze, Yufei Zhang, Haixin Chen, and Kaiwen Deng. "Aerodynamic Optimization of Turbine Based Combined Cycle Nozzle." International Journal of Turbo & Jet-Engines 35, no. 4 (December 19, 2018): 385–94. http://dx.doi.org/10.1515/tjj-2016-0052.

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Abstract This paper aims at optimizing a Turbine Based Combined Cycle (TBCC) nozzle for upgrading its aerodynamic performance in multiple flight conditions. An in-house RANS solver called NSAWET is employed for aerodynamic evaluation. The optimizer is a differential evolution algorithm combined with a response surface. Firstly, a two-dimensional model of the initial TBCC nozzle system is investigated. The flow field of the nozzle contains complicated shockwave interactions that cause thrust loss. Then multi-point aerodynamic optimization of a two-dimensional ramjet nozzle is carried out, which objectives are to maximize the thrust coefficients at Mach numbers 2.5, 3.0 and 4.0. The objective functions are increased substantially at the first two Mach numbers after optimization, while slightly decreased at the last Mach number. The turbine flow path is built up based on the optimized profile and the performances in typical flight conditions are validated. Results demonstrate that both the ramjet and turbine nozzles are improved in most flight conditions.

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