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Showing papers in "Journal of Propulsion and Power in 2017"


Journal ArticleDOI
TL;DR: In this article, rotating detonation engines are compared to pulsed detonation engine and they are shown to produce thrust with fuel efficiencies similar to those associated with pulsed engines while operating on gaseous hydrocarbon fuels.
Abstract: Recent accomplishments related to the performance, application, and analysis of rotating detonation engine technologies are discussed. The pioneering development of optically accessible rotating detonation engines coupled with the application of established diagnostic techniques is enabling a new research direction. In particular, OH* chemiluminescence images of detonations propagating through the annular channel of a rotating detonation engine are reported and appear remarkably similar to computational fluid dynamic results of rotating detonation engines published in the literature. Specific impulse measurements of rotating detonation engines and pulsed detonation engines are shown to be quantitatively similar for engines operating on hydrogen/air and ethylene/air mixtures. The encouraging results indicate that rotating detonation engines are capable of producing thrust with fuel efficiencies that are similar to those associated with pulsed detonation engines while operating on gaseous hydrocarbon fuels....

157 citations


Journal ArticleDOI
TL;DR: In this article, the physical principles of aerodynamic power savings from boundary layer ingestion propulsion and a quantitative evaluation of the boundary-layer ingestion bene... are presented. But they do not consider the impact of boundary layer insertion on the propulsion system.
Abstract: This paper presents a description of the physical principles of aerodynamic power savings from boundary layer ingestion propulsion and a quantitative evaluation of the boundary layer ingestion bene...

112 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a guide to standardize the methods of performing correct and accurate Langmuir probe measurements within the plasma environment produced by an electric propulsion device, which is similar to our approach.
Abstract: Presented in this work is a guide to standardize the methods of performing correct and accurate Langmuir probe measurements within the plasma environment produced by an electric propulsion device. ...

99 citations


Journal ArticleDOI
TL;DR: The accurate, direct measurement of thrust or impulse is one of the most critical elements of electric thruster characterization, and it is the most difficult measurement to make as mentioned in this paper, and therefore it is difficult to obtain accurate measurements.
Abstract: The accurate, direct measurement of thrust or impulse is one of the most critical elements of electric thruster characterization, and it is one of the most difficult measurements to make. This pape...

85 citations


Journal ArticleDOI
TL;DR: In this article, standard practices, guidelines, and recommendations for experimental methods and analysis techniques that aim to standardize community practices, to mitigate test environment effects, and to reduce systematic measurement error in order to improve plume predictions in the space environment.
Abstract: Faraday probes are a common plasma diagnostic used to determine the local ion charge flux of electric propulsion plumes. Standard practices, guidelines, and recommendations are provided for experimental methods and analysis techniques that aim to standardize community practices, to mitigate test environment effects, and to reduce systematic measurement error in order to improve plume predictions in the space environment. The approaches are applicable to time-averaged plasma properties in the near-field and far-field of electric propulsion plumes, with emphasis on Hall effect thrusters and gridded ion thrusters. Considerations for other electric propulsion technologies are provided, including electrosprays, arcjets, and electromagnetic thruster concepts. These test strategies are expected to increase the quality of comparisons between different thrusters and vacuum environments, thereby broadening the applicability of ground-based measurements and enhancing the fidelity for on-orbit predictions and modelin...

80 citations


Journal ArticleDOI
TL;DR: In this paper, a method for modeling the internal flowfield in a rotating detonation engine is developed using shockexpansion theory combined with the steady two-dimensional isentropic method of characteristics.
Abstract: A method for modeling the internal flowfield in a rotating detonation engine is developed using shock-expansion theory combined with the steady two-dimensional isentropic method of characteristics. An analytical model using the oblique shock relations, the Prandtl–Meyer function, and the detonation jump conditions is used to determine the basic shock structure. Once the structure is known, a shock-fitted method of characteristics solution is marched out to generate the rest of the flowfield. Reactant injection is handled analytically by solving the conservation equations for a flow undergoing a sudden expansion along with the method of characteristics compatibility relations to provide a new boundary condition. A new solution is then initialized using information from the previous solution to calculate the new shock structure. This process is repeated until the solutions converge. The converged solution is the ideal steady-state solution of a rotating detonation engine in the wave-fixed reference frame. T...

77 citations


Journal ArticleDOI
TL;DR: A vacuum test campaign evaluating the impulsive thrust performance of a tapered radio-frequency test article excited in the transverse magnitude 212 mode at 1937 MHz has been completed.
Abstract: A vacuum test campaign evaluating the impulsive thrust performance of a tapered radio-frequency test article excited in the transverse magnitude 212 mode at 1937 MHz has been completed. The test campaign consisted of a forward thrust phase and reverse thrust phase at less than 8×10−6 torr vacuum with power scans at 40, 60, and 80 W. The test campaign included a null thrust test effort to identify any mundane sources of impulsive thrust; however, none were identified. Thrust data from forward, reverse, and null suggested that the system was consistently performing with a thrust-to-power ratio of 1.2±0.1 mN/kW.

69 citations


Journal ArticleDOI
TL;DR: In this article, a recommended practice for making pressure measurements, pressure diagnostics, and calculating effective pumping speeds with justification is presented, along with a recommended procedure for measuring the effective pumping speed with justification.
Abstract: The electric propulsion community has been implored to establish and implement a set of universally applicable test standards during the research, development, and qualification of electric propulsion systems. Variability between facility-to-facility and more importantly ground-to-flight performance can result in large margins in application or aversion to mission infusion. Performance measurements and life testing under appropriate conditions can be costly and lengthy. Measurement practices must be consistent, accurate, and repeatable. Additionally, the measurements must be universally transportable across facilities throughout the development, qualification, spacecraft integration, and on-orbit performance. A recommended practice for making pressure measurements, pressure diagnostics, and calculating effective pumping speeds with justification is presented.

67 citations


Journal ArticleDOI
TL;DR: In this paper, the impact of different scaling parameters on the performance of rotating detonation engines of various annular detonation channel widths and the impact on different scales of the devices is investigated.
Abstract: Thrust stand testing is conducted on rotating detonation engines of various annular detonation channel widths and the impact of different scaling parameters on the performance of the devices is dis...

64 citations


Journal ArticleDOI
TL;DR: In this paper, OpenFoam, an open source unsteady Reynolds-averaged Navier-Stokes software, was examined to analyze rotating detonation combustors.
Abstract: In this paper, OpenFoam, an open source unsteady Reynolds-averaged Navier–Stokes software was carefully examined to analyze rotating detonation combustors. This tool was subsequently used to quantify the effect of the outlet conditions on five different exhaust nozzle geometries. Both detonation and deflagration of the hydrogen–air mixture were taken into account in the source terms of the species transport equation. The premixed H2–air mixture was injected at three different total pressures, ranging from 0.4 to 0.8 MPa. First, the rotating detonation combustor was described, and then five different nozzles were investigated: straight duct, conical, Bezier outer wall, Bezier inner wall, and two Bezier surfaces. All the nozzles were compared regarding their outlet total temperature, pressure gain, exit Mach number, and outlet flow angle. The use of a straight duct nozzle generated a noticeable drop in pressure gain of about 27% compared to the baseline combustor. The conical nozzle expanded the combustor o...

57 citations


Journal ArticleDOI
TL;DR: In this paper, a reduced-order model of the thermodynamic cycle within a rotating detonation engine system is presented with an emphasis on the identification of the parameters that drive performance and the valuations.
Abstract: Reduced-order modeling of the thermodynamic cycle within a rotating detonation engine system is presented with an emphasis on the identification of the parameters that drive performance and the val...

Journal ArticleDOI
TL;DR: In this paper, the authors used a disk-shaped rotating detonation combustor with a combustion chamber with flat-plane glass walls to observe the structure of the wave propagation in rotating detonations and compared self-luminescence, shadowgraphs, and schlieren visualization experiments.
Abstract: The rotating detonation engine is a propulsion system that obtains thrust using continuously existing detonation waves. A rotating detonation combustor usually has an annular shape that allows detonation waves to propagate in the circumferential direction. In this study, we used a disk-shaped rotating detonation combustor with a combustion chamber with flat-plane glass walls to observe the structure of the phenomena. Self-luminescence, shadowgraphs, and schlieren visualization experiments were performed and compared. Results revealed that detonation waves were propagating in a mixture layer of three gases, fuel, oxidizer, and burned gas at 1600 to 900 m/s; Chapman-Jouguet velocity was 2376 m/s. Waves maintained a three-dimensional complicated wave shape in the disk-shaped combustion chamber with parallel-jet injectors.

Journal ArticleDOI
TL;DR: In this article, the authors provide recommended methods for building, operating, and taking plasma potential measurements from electron-emitting probes in electric propulsion devices, including Hall thrusters, gridded ion engines, and others.
Abstract: This article provides recommended methods for building, operating, and taking plasma potential measurements from electron-emitting probes in electric propulsion devices, including Hall thrusters, gridded ion engines, and others. The two major techniques, the floating point technique and the inflection point technique, are described in detail as well as calibration and error-reduction methods. The major heating methods are described as well as the various considerations for emissive probe construction. Special considerations for electric propulsion plasmas are addressed, including high-energy densities, ion flows, magnetic fields, and potential fluctuations. Recommendations for probe design and operation are provided.

Journal ArticleDOI
TL;DR: In this paper, the combustion behavior of paraffin-based hybrid rocket fuels with gaseous oxygen as an oxidizer has been analyzed in detail, and regression rate tests have been done in a two-dimensional radial microburner at the DLR, German Aerospace Center and at the Space Propulsion Laboratory.
Abstract: The combustion behavior of paraffin-based hybrid rocket fuels with gaseous oxygen as an oxidizer has been analyzed in detail. Regression rate tests have been done in a two-dimensional radial microburner at the DLR, German Aerospace Center and at the Space Propulsion Laboratory. Fuel samples have been characterized by viscosity measurements, tensile tests, and a differential scanning calorimeter. Tensile tests showed significant improvement in maximum stress and elongation when polymers in low concentration were added to the paraffin samples. The values of the liquid fuel viscosities differed significantly between the selected fuels. This affected the droplet entrainment process during combustion and the regression rates of the fuels. The entrainment and regression rate increased for the decreasing fuel liquid layer viscosity. An exponential relation has been found between the liquid fuel layer viscosity and the regression rate, which can be used to predict the regression rate of new liquefying fuels by measuring their viscosity.

Journal ArticleDOI
TL;DR: The successful application of a fully shielding magnetic field topology in a low-power Hall thruster was demonstrated through the testing of the MaSMi-60 Hall thrusters as mentioned in this paper.
Abstract: The successful application of a fully shielding magnetic field topology in a low-power Hall thruster is demonstrated through the testing of the MaSMi-60 Hall thruster (an improved variant of the or...

Journal ArticleDOI
TL;DR: In this paper, a premixed supply of fuel and oxidizer was fed through five concentric feed slots and detonated in a rotating detonation engine, representing the first known successful airbreathing premixed rotati...
Abstract: A premixed supply of fuel and oxidizer was fed through five concentric feed slots and detonated in a rotating detonation engine, representing the first known successful airbreathing premixed rotati...

Journal ArticleDOI
TL;DR: In this paper, a pintle injector was used for developing throttleable rocket engines, where variable-area injectors are suitable choices for developing a rocket engine because it is difficult to efficiently control thrust when fixed-area injectionors are used.
Abstract: Variable-area injectors are suitable choices for developing throttleable rocket engines because it is difficult to efficiently control thrust when fixed-area injectors are used. A pintle injector i...

Journal ArticleDOI
TL;DR: In this paper, an axisymmetric, multispecies compressible flow solver was used to solve the longitudinal combustion instability in liquid-propellant rocket engines.
Abstract: Longitudinal combustion instability in liquid-propellant rocket engines is investigated using an in-house axisymmetric, multispecies compressible flow solver. Turbulence is treated using a hybrid R...

Journal ArticleDOI
TL;DR: In this article, the mixing and combustion characteristics of liquid-oxygen/kerosene bi-swirl injectors are investigated under the supercritical conditions typical of contemporary rocket engines.
Abstract: The mixing and combustion characteristics of liquid-oxygen/kerosene bi-swirl injectors are investigated under the supercritical conditions typical of contemporary rocket engines. The basis of the study is a large-eddy simulation technique combined with a unified treatment of real-fluid thermodynamics. The turbulence/chemistry interaction is treated using a laminar flamelet library approach. Emphasis is placed on the near-field flow and flame development downstream of the inner swirler. The flame is found to be stabilized by two counter-rotating vortices in the wake region of the liquid-oxygen post, which is covered by the kerosene-rich mixture. The width of the kerosene annulus is found to significantly affect the injector behavior. A wider annulus induces a larger spreading angle of the liquid-oxygen stream, which intercepts the kerosene stream in a more efficient way. Increasing the annulus width, however, imposes a wake region in a broader zone. The resultant flame becomes relatively unstable if the fl...

Journal ArticleDOI
TL;DR: Theoretical and experimental methods were developed to investigate the charging characteristics anticipated to be observed on spacecraft during the operation of electrospray thrusters as mentioned in this paper, and the results from the experimental tests demonstrate that neutralization with heavy ionic species is indeed possible.
Abstract: Theoretical and experimental methods were developed to investigate the charging characteristics anticipated to be observed on spacecraft during the operation of electrospray thrusters These devices produce positively and negatively charged particles of similar mass and velocities An electrical model of this configuration was created to predict the charging properties of electrically isolated systems This model simulates a bipolar electrospray-thruster system Experiments were conducted on a test bed, in which a mock-up satellite is magnetically levitated inside a vacuum chamber The mock-up is equipped with batteries, power conditioning, radio transmitter, and electrospray thrusters The results from the experimental tests demonstrate that neutralization with heavy ionic species is indeed possible The thrusters are able to fire in a bipolar configuration for long periods of time inducing bounded spacecraft charging in the range from −400 to +600 V when emitting currents of about 20 μA It was found

Journal ArticleDOI
TL;DR: In this paper, a low-order analytical performance model for the rocket-mode rotating detonation engine was developed, starting from the general form of the continuity, momentum, and energy equations and integrati...
Abstract: A low-order analytical performance model for the rocket-mode rotating detonation engine was developed. Starting from the general form of the continuity, momentum, and energy equations and integrati...

Journal ArticleDOI
TL;DR: In this article, supercritical combustion has attracted significant interest due to its applications in high-pressure combustion devices, however, validation of super-critical combustion modeling has not been well studied.
Abstract: Supercritical combustion has attracted significant interest due to its applications in high-pressure combustion devices. Validation of supercritical combustion modeling, however, has not been well ...

Journal ArticleDOI
TL;DR: In this article, the cellular structure of the detonation appears near the inner wall as the circumferential grid resolution increases, however, the effects of the grid resolution are small on Isp.
Abstract: Numerical simulations of three-dimensional rotating detonation engines for a hydrogen–oxygen mixture are performed using the detailed chemistry model The grid-resolution study indicates that the cellular structure of the detonation appears near the inner wall as the circumferential grid resolution increases However, the effects of the grid resolution are small on Isp The grid resolution for the high-mass-flow cases should be carefully considered because the rotating detonation velocity increases to produce higher thrust under the low grid resolution As the annular width increases, a complicated shock structure such as a Mach stem appears, and the cycle time decreases The effects of the annular width are small on Isp As the number of the rotating detonations increases, the asymmetric detonation heads rotate along the circumferential direction with the same cycle time after 30 cycles Isp for the two-waved rotating detonation engine decreases approximately 10% less than Isp for the one-waved rotating

Journal ArticleDOI
TL;DR: In this article, a system-level optimization study of the impulse transfer thruster alone and of the overall electric propulsion subsystem is presented for an ion beam shepherd mission example, and an optimum design point is found for minimum overall power consumption in both cases.
Abstract: The ion beam shepherd is an innovative contactless technique for space debris removal in which an impulse transfer thruster pushes the debris object through the action of a plasma plume and an impulse compensation thruster maintains formation flying. The optimal operational point of both thrusters strongly depends on their characteristics and on the physics of the plasma plume expansion into vacuum. With the use of dedicated thruster performance models, complemented with simplified plume expansion and plasma–debris interaction models, a system-level optimization study of the impulse transfer thruster alone and of the overall electric propulsion subsystem is presented for an ion beam shepherd mission example. An optimum design point is found for minimum overall power consumption in both cases.

Journal ArticleDOI
TL;DR: The microfabricated multiemitter array is an ideal implementation of t... as mentioned in this paper, which can deliver the efficient primary propulsion and attitude control actuation needed by small satellites.
Abstract: Electrospray thrusters can deliver the efficient primary propulsion and attitude control actuation needed by small satellites. The microfabricated multiemitter array is an ideal implementation of t...

Journal ArticleDOI
TL;DR: The applicability of a fully shielding magnetic field topology to a low-power xenon Hall thruster was demonstrated through testing of the MaSMi-60 as mentioned in this paper, although the discharge channel lifetime was signi...
Abstract: The applicability of a fully shielding magnetic field topology to a low-power xenon Hall thruster was demonstrated through testing of the MaSMi-60. Although the discharge channel lifetime was signi...

Journal ArticleDOI
Nan Li1, Juntao Chang1, Daren Yu1, Wen Bao1, Yanping Song1 
TL;DR: In this article, a mathematical model is established based on Billig's correlation and surface pressure datasets in the current paper, and the start and end positions of the rapid forward motion are located where the pressure gradient approaches zero.
Abstract: The existence of the complex compression and expansion waves in an isolator induces a special motion path of the shock train. Numerical simulations with two different inlet models are conducted. The results indicate that the local parameters govern the shock train’s motion, and the pressure gradient along the surface plays an extremely important role. The shock train’s location is determined by the entrance condition and backpressure, whereas it is the parameter along the surface that determines its path. The start and end positions of the rapid forward motion are located where the pressure gradient approaches zero. Streamwise parameters and the surface pressure gradient are introduced in Waltrup and Billig’s (“Structure of ShockWaves in Cylindrical Ducts,” AIAA Journal, Vol. 11, No. 10, 1973, pp. 1404–1408) empirical correlation to characterize the rapid forward motion. Then, a mathematical model is established based on Billig’s correlation and surface pressure datasets in the current paper.

Journal ArticleDOI
TL;DR: In this article, an analytical model of the facility background flow environment is developed to accommodate facilities with different geometries and pump placements, as well as compute the ingested flow rate of background neutrals into a given Hall effect thruster.
Abstract: The particle-based coupling between background gas flows in vacuum test facilities and neutral ingestion into Hall effect thrusters is investigated. An analytical model of the facility background flow environment is developed to accommodate facilities with different geometries and pump placements, as well as compute the ingested flow rate of background neutrals into a given Hall effect thruster. The ingested flow rates computed by the model are shown to predict previous empirical datasets taken using the 5 kW P5, the 6 kW H6, and the 1.5 kW SPT-100 Hall effect thrusters in different test facilities to within the experimental uncertainty. When compared to predictions generated assuming ingestion by the random flux of neutral particles, the ingested flow rates computed by the background flow model are shown to be 40 to 70% closer to the empirical measurements without requiring any semiempirical inputs. It is also shown that the neutral ingestion at a fixed facility pressure can vary by as much as 91%, sugge...

Journal ArticleDOI
TL;DR: The experiments described in this paper, along with companion data sets, aim to isolate the chemical kinetic effects and turbulence-chemistry interaction from the fuel-air mixing process in a dual-mode scramjet combustion environment.
Abstract: Hypersonic airbreathing engines rely on scramjet combustion processes, which involve high-speed, compressible, and highly turbulent reacting flows. The combustion environment and the turbulent flam...

Journal ArticleDOI
Wei Yao1, Yueming Yuan1, Xiaopeng Li1, Jing Wang1, Kun Wu1, Xuejun Fan1 
TL;DR: In this paper, the flow and combustion characteristics in the round and round-to-elliptic shape-transition scramjet combustors were investigated and the combustion performance of nonrectangular supersonic combustors was explored.
Abstract: To explore the combustion performance of nonrectangular supersonic combustors, the flow and combustion characteristics in the round and round-to-elliptic shape-transition scramjet combustors were c...