scholarly journals Hot-fire testing of liquid oxygen/hydrogen single coaxial injector at high-pressure conditions with optical diagnostics

2019 ◽  
Author(s):  
D.I. Suslov ◽  
J.S. Hardi ◽  
B. Knapp ◽  
M. Oschwald
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Optical Diagnostics ◽  
Liquid Oxygen ◽  
Experimental Investigations ◽  
Rocket Engines ◽  
Chamber Length ◽  
Substantial Progress ◽  
Liquid Rocket ◽  
Coaxial Injector

Injector behavior is of utmost importance for the performance and stability of liquid rocket engines (LREs). A major problem is getting a highly efficient homogeneous mixture and effective chemical reaction of fuels at minimum chamber length. Despite substantial progress in numerical simulations, a need for experimental data at representative conditions for development and validation of numerical design tools still exists. Therefore, in the framework of the DLR-project “ProTau,” the authors have performed tests to create an extended data base for numerical tool validation for high-pressure liquid oxygen (LOx) / hydrogen combustion. During the experimental investigations, a windowed DLR subscale thrust chamber model “C” (designated BKC) has been operated over a broad range of conditions at reduced pressures of approximately 0.8 (4 MPa), 1 (5 MPa), and 1.2 (6 MPa) with respect to the thermodynamic critical pressure of oxygen. Liquid oxygen and gaseous hydrogen (GH2) have been injected through a single coaxial injector element at temperatures of ~ 120 and ~ 130 K, respectively. High-speed optical diagnostics have been implemented, including imaging of OH* emission and shadowgraph imaging at frequencies from 8 up to 10 kHz to visualize the flow field.

scholarly journals Recent Experimental Efforts on High-Pressure Supercritical Injection for Liquid Rockets and Their Implications

2012 ◽  
Vol 2012 ◽  
pp. 1-31 ◽  
Author(s):  
Bruce Chehroudi
Keyword(s):  
High Pressure ◽  
Critical Point ◽  
Space Shuttle ◽  
Specific Impulse ◽  
Liquid Oxygen ◽  
Liquid Jets ◽  
Rocket Engines ◽  
Liquid Rocket Engines ◽  
Liquid Rocket ◽  
Air Force Research Laboratory

Pressure and temperature of the liquid rocket thrust chambers into which propellants are injected have been in an ascending trajectory to gain higher specific impulse. It is quite possible then that the thermodynamic condition into which liquid propellants are injected reaches or surpasses the critical point of one or more of the injected fluids. For example, in cryogenic hydrogen/oxygen liquid rocket engines, such as Space Shuttle Main Engine (SSME) or Vulcain (Ariane 5), the injected liquid oxygen finds itself in a supercritical condition. Very little detailed information was available on the behavior of liquid jets under such a harsh environment nearly two decades ago. The author had the opportunity to be intimately involved in the evolutionary understanding of injection processes at the Air Force Research Laboratory (AFRL), spanning sub- to supercritical conditions during this period. The information included here attempts to present a coherent summary of experimental achievements pertinent to liquid rockets, focusing only on the injection of nonreacting cryogenic liquids into a high-pressure environment surpassing the critical point of at least one of the propellants. Moreover, some implications of the results acquired under such an environment are offered in the context of the liquid rocket combustion instability problem.

scholarly journals Numerical Investigation of Injection, Mixing and Combustion in Rocket Engines Under High-Pressure Conditions

2020 ◽  
pp. 209-221
Author(s):  
Christoph Traxinger ◽  
Julian Zips ◽  
Christian Stemmer ◽  
Michael Pfitzner
Keyword(s):  
High Pressure ◽  
Large Eddy Simulations ◽  
Experimental Investigations ◽  
High Fidelity ◽  
Rocket Engines ◽  
Eddy Simulation ◽  
Liquid Rocket Engines ◽  
Large Eddy ◽  
Numerical Tools ◽  
Liquid Rocket

Abstract The design and development of future rocket engines severely relies on accurate, efficient and robust numerical tools. Large-Eddy Simulation in combination with high-fidelity thermodynamics and combustion models is a promising candidate for the accurate prediction of the flow field and the investigation and understanding of the on-going processes during mixing and combustion. In the present work, a numerical framework is presented capable of predicting real-gas behavior and nonadiabatic combustion under conditions typically encountered in liquid rocket engines. Results of Large-Eddy Simulations are compared to experimental investigations. Overall, a good agreement is found making the introduced numerical tool suitable for the high-fidelity investigation of high-pressure mixing and combustion.

High Speed Optical Diagnostics in a High Pressure, RP-2/GOx Fueled Combustor

2017 ◽  
Author(s):  
Henry C. Ballance ◽  
Oleksandr Bibik ◽  
Timothy S. Cook ◽  
Stephen Danczyk ◽  
Stephen A. Schumaker ◽  
...  
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Optical Diagnostics

Fluid Mode Excitation in Launch Vehicle Feed Lines Induced by Pogo Accumulator Venting

2014 ◽  
Author(s):  
Kirk W. Dotson ◽  
Brian H. Sako ◽  
Trinh T. Nguyen
Keyword(s):  
Space Vehicle ◽  
Launch Vehicle ◽  
Liquid Oxygen ◽  
Rocket Engines ◽  
Launch Vehicles ◽  
Feed Line ◽  
Large Pressure ◽  
Structural Responses ◽  
Flow Oscillations ◽  
Liquid Rocket

Launch vehicles with liquid rocket engines have feed lines through which propellants flow to the engine. To prevent feedback between structural responses and propellant pressure and flow oscillations, a compliant device called a pogo accumulator is typically installed in the propellant feed line. Even if a catastrophic interaction is thus averted, the fluid-induced structural responses may exceed those for important flight events such as liftoff and atmospheric buffeting. In that case, the fluid-induced excitation must be predicted in order to ensure adequate structural margins for the launch vehicle and space vehicle hardware. Venting of compliant gas in the pogo accumulator prior to engine shutdown is known to exacerbate the fluid-induced excitation. In particular, for the Atlas V launch vehicle, a 5–7 Hz fluid mode with large pressure gains at the aft end of the liquid oxygen feed line often excites structural modes just prior to engine cutoff. A methodology for the prediction of these structural responses is presented.

scholarly journals Quantitative predictions of cavitation presence and erosion-prone locations in a high-pressure cavitation test rig

2017 ◽  
Vol 819 ◽  
pp. 21-57 ◽  
Author(s):  
Phoevos Koukouvinis ◽  
Nicholas Mitroglou ◽  
Manolis Gavaises ◽  
Massimo Lorenzi ◽  
Maurizio Santini
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Transient Flow ◽  
Mass Transfer Rate ◽  
Operation Time ◽  
Working Fluid ◽  
Experimental Investigations ◽  
Micro Ct ◽  
Mixture Phase ◽  
Cavity Shedding

Experiments and numerical simulations of cavitating flow inside a single-orifice nozzle are presented. The orifice is part of a closed flow circuit, with diesel fuel as the working fluid, designed to replicate the main flow pattern observed in high-pressure diesel injector nozzles. The focus of the present investigation is on cavitation structures appearing inside the orifice, their interaction with turbulence and the induced material erosion. Experimental investigations include high-speed shadowgraphy visualization, X-ray micro-computed tomography (micro-CT) of time-averaged volumetric cavitation distribution inside the orifice as well as pressure and flow rate measurements. The highly transient flow features that are taking place, such as cavity shedding, collapse and vortex cavitation (also known as ‘string cavitation’), have become evident from high-speed images. Additionally, micro-CT enabled the reconstruction of the orifice surface, which provided locations of cavitation erosion sites developed after sufficient operation time. The measurements are used to validate the presented numerical model, which is based on the numerical solution of the Navier–Stokes equation, taking into account compressibility of both the liquid and liquid–vapour mixture. Phase change is accounted for with a newly developed mass transfer rate model, capable of accurately predicting the collapse of vaporous structures. Turbulence is modelled using detached eddy simulation and unsteady features such as cavitating vortices and cavity shedding are observed and discussed. The numerical results show agreement within validation uncertainty with the obtained measurements.

scholarly journals Numerical Investigation on the Thermal Behaviour of a LOx/LCH4 Demonstrator Cooling System

Aerospace ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 151
Author(s):  
Daniele Ricci ◽  
Francesco Battista ◽  
Manrico Fragiacomo
Keyword(s):  
Thermal Behaviour ◽  
Cooling System ◽  
Thermal Analyses ◽  
Operating Conditions ◽  
Liquid Oxygen ◽  
Rocket Engines ◽  
Successful Operation ◽  
Combustion Gases ◽  
Cooling Jacket ◽  
Liquid Rocket

Reliability of liquid rocket engines is strictly connected with the successful operation of cooling jackets, able to sustain the impressive operative conditions in terms of huge thermal and mechanical loads, generated in thrust chambers. Cryogenic fuels, like methane or hydrogen, are often used as coolants and they may behave as transcritical fluids flowing in the jackets: after injection in a liquid state, a phase pseudo-change occurs along the chamber because of the heat released by combustion gases and coolants exiting as a vapour. Thus, in the development of such subsystems, important issues are focused on numerical methodologies adopted to simulate the fluid thermal behaviour inside the jackets, design procedures as well as manufacturing and technological process topics. The present paper includes the numerical thermal analyses regarding the cooling jacket belonging to the liquid oxygen/liquid methane demonstrator, realized in the framework of the HYPROB (HYdrocarbon PROpulsion test Bench) program. Numerical results considering the nominal operating conditions of cooling jackets in the methane-fuelled mode and the water-fed one are included in the case of the application of electrodeposition process for manufacturing. A comparison with a similar cooling jacket, realized through the conventional brazing process, is addressed to underline the benefits of the application of electrodeposition technology.

Spray and Combustion Modeling in High Pressure Cryogenic Jet Flames

2012 ◽  
Author(s):  
Maria Grazia De Giorgi ◽  
Aldebara Sciolti ◽  
Antonio Ficarella
Keyword(s):  
Supercritical Pressure ◽  
Liquid Oxygen ◽  
Rocket Engines ◽  
Liquid Propellant ◽  
Combustion Modeling ◽  
Discrete Phase ◽  
Real Behavior ◽  
Shear Coaxial Injector ◽  
Coaxial Injector ◽  
Propellant Rocket

The aim of the present work is the investigation of the combustion phenomenon in liquid-propellant rocket engines. The combustion of liquid oxygen and gaseous methane in a shear coaxial injector under supercritical pressure was analyzed. To realize an efficient numerical description of the phenomena, it is important to treat the LOx jet in a manner which takes into account its real behavior. In the present work different kinetics, combustion models and thermodynamics approaches were used in association with the description of the jet as a discrete phase. For all the approaches used, a comparison with experimental data from literature was performed.

Evaluation of Wear Ring Seals for High-Speed, High-Pressure Turbopumps

1969 ◽  
Vol 91 (3) ◽  
pp. 438-448
Author(s):  
F. R. Mallaire ◽  
L. H. Nelson ◽  
P. S. Buckmann
Keyword(s):  
High Pressure ◽  
High Velocity ◽  
High Speed ◽  
Fluid Film ◽  
Pump Impeller ◽  
Evaluation Program ◽  
Design Requirements ◽  
Liquid Rocket ◽  
Principal Design

This paper describes a seal evaluation program for application as pump impeller wear rings for high-pressure, high-speed liquid rocket turbopumps. The principal design requirements were to control the leakage to values consistent with efficiency requirements and to eliminate potential explosions resulting from high velocity rubbing at the required clearances. Two approaches were taken: the first allowed rubbing of rotating labyrinth teeth on stationary, soft compatible inserts; the second utilized hydrostatic seals which maintained a fluid film between the stationary seal and the rotating wear ring.

scholarly journals New methods in optical diagnostics on production engines with only minor modifications

2009 ◽  
Vol 137 (2) ◽  
pp. 50-61
Author(s):  
Werner HENTSCHEL
Keyword(s):  
Cylinder Head ◽  
High Speed ◽  
Laser Diagnostics ◽  
Direct Injection ◽  
Combustion Process ◽  
Green Light ◽  
Cylinder Liner ◽  
Optical Diagnostics ◽  
Experimental Investigations ◽  
Optical Probes

The aim of this paper is to demonstrate the performance of micro-invasive optical diagnostics as advanced tools in the development process of modern direct-injection (DI) gasoline engines. The use of endoscopes and optical probes minimise the mechanical modifications on the engine necessary to achieve the optical access to the combustion chamber. No expensive optical engines with large optical windows are required but only small holes of about 10 mm in the cylinder head or in a plate between cylinder head and cylinder liner are used to apply laser diagnostics. Basic in-cylinder phenomena, such as the formation of the flow field, the penetration of the spray at high fuel pressure, the interaction of spray and flow, the formation of an ignitable mixture and the start of combustion are analysed in detail. High-power solid-state pulsed lasers emitting ultraviolet or green light, state-of the-art high-speed colour video cameras, and newly designed optical probes were used for the investigations. Selected results from current research and development work demonstrate the capability of micro-invasive techniques and pinpoint how the design of the combustion process benefits from these experimental investigations.

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