scholarly journals Intake Flow Analysis of a Pulsed Detonation Engine

2016 ◽  
Vol 139 (4) ◽  
Author(s):  
Joshua A. Strafaccia ◽  
Semih M. Ölçmen ◽  
John L. Hoke ◽  
Daniel E. Paxson
Keyword(s):  
Fluid Dynamic ◽  
Flow Analysis ◽  
Engine Performance ◽  
Fuel Injector ◽  
Pulse Detonation ◽  
Pulsed Detonation Engine ◽  
Pulsed Detonation ◽  
Fill Fraction ◽  
Detonation Engine ◽  
Intake Flow

Unsteady flow within the intake system of a hydrogen–air pulse detonation engine (PDE) has been analyzed using a quasi-one-dimensional (Q1D) computational fluid dynamic (CFD) code. The analysis provides insight into the unsteady nature of localized equivalence ratios and their effects on PDE performance. For this purpose, a code originally configured to model the PDE tube proper was modified to include a 6.1 m long intake with a single fuel injector located approximately 3.05 m upstream of the primary intake valve. The results show that constant fuel mass flow rate injection from the injector creates large local variations in equivalence ratio throughout the PDE within a cycle. The effect of fill fraction on the engine performance is better described with the presence of the inlet model. However, the effect of ignition delay is shown to be better predicted with a model without the inlet.

scholarly journals Research on Optical Diagnostic Method of PDE Working Status Based on Visible and Near-Infrared Radiation Characteristics

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5703
Author(s):  
Xiaolong Huang ◽  
Ning Li ◽  
Yang Kang
Keyword(s):  
Diagnostic Method ◽  
Near Infrared ◽  
Radiant Energy ◽  
Optical Diagnostics ◽  
Time Duration ◽  
Pulsed Detonation Engine ◽  
Optical Diagnostic ◽  
Pulsed Detonation ◽  
Fill Fraction ◽  
Detonation Engine

Fill fraction not only has a profound impact on the process of deflagration to detonation in pulsed detonation engine, but also affects the propulsion performance in both flight and ground tests. In this paper, a novel optical diagnostic method based on detonation exhaust radiation in visible and near-infrared region within 300–2600 nm is developed to determine the current working state in the gas–liquid two-phase pulsed detonation cycle. The results show that the radiation characteristic in each stage of detonation cycle is unique and can be a good indicator to infer the fill fraction. This is verified experimentally by comparison with the laser absorption spectroscopy method, which utilizes a DFB laser driven by ramp injection current to scan H2O transition of 1391.67 nm at a frequency of 20 kHz. Due to concentrated radiation intensity, time duration reaching accumulated radiant energy ratio of 50% in detonation status would be smaller than 1.2 ms, and detonation status would be easily distinguished from deflagration with this critical condition. In addition, the variation of important intermediates OH, CH, and C2 radicals during detonation combustion are obtained according to the analysis of detonation spectrum, which can also be proposed as a helpful optical diagnostics method for the combustion condition based on C radical concentration. The study demonstrates the feasibility of optical diagnostics based on radiation in visible and near-infrared regions, which could provide an alternative means to diagnose and improve pulsed detonation engine performance.

Numerical Study of Pulse Detonation Engine with One-step Overall Reaction Model

2015 ◽  
Vol 65 (4) ◽  
pp. 265
Author(s):  
P. Srihari ◽  
M.A. Mallesh ◽  
G. Sai Krishna Prasad ◽  
B.V.N. Charyulu ◽  
D.N. Reddy
Keyword(s):  
Numerical Study ◽  
Reaction Model ◽  
Flow Conditions ◽  
Von Neumann ◽  
Pulse Detonation ◽  
Pulsed Detonation Engine ◽  
Pulsed Detonation ◽  
Reaction Models ◽  
Detonation Engine ◽  
One Step

<p>This paper presents an insight for the study of transient, compressible, intermittent pulsed detonation engine with one-step overall reaction model to reduce the computational complexity in detonation simulations. Investigations are done on flow field conditions developing inside the tube with the usage of irreversible one-step chemical reactions for detonations. In the present simulations 1-D and 2-D axisymmetric tubes are considered for the investigation. The flow conditions inside the detonation tube are estimated as a function of time and distance. Studies are also performed with different grid sizes which influence the prediction of Von-Neumann spike, CJ Pressure and detonation velocity. The simulation result from the single-cycle reaction model agrees well with the previous published literature of multi-step reaction models. The present studies shows that one-step overall reaction model is sufficient to predict the flow properties with reasonable accuracy. Finally, the results from the present study were compared and validated using NASA CEA.</p><p><strong>Defence Science Journal, Vol. 65, No. 4, July 2015, pp. 265-271, DOI: http://dx.doi.org/10.14429/dsj.65.8730</strong></p>

scholarly journals Adjoint-based optimisation of detonation initiation by a focusing shock wave

Shock Waves ◽  
2021 ◽  
Author(s):  
S. Bengoechea ◽  
J. Reiss ◽  
M. Lemke ◽  
J. Sesterhenn
Keyword(s):  
Shock Wave ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Detonation Initiation ◽  
Axisymmetric Nozzle ◽  
Exponential Factor ◽  
Pulsed Detonation Engine ◽  
Pulsed Detonation ◽  
Detonation Engine ◽  
Adjoint Approach

AbstractAn optimisation study of a shock-wave-focusing geometry is presented in this work. The configuration serves as a reliable and deterministic detonation initiator in a pulsed detonation engine. The combustion chamber consists of a circular pipe with one convergent–divergent axisymmetric nozzle, acting as a focusing device for an incoming shock wave. Geometrical changes are proposed to reduce the minimum shock wave strength necessary for a successful detonation initiation. For that purpose, the adjoint approach is applied. The sensitivity of the initiation to flow variations delivered by this method is used to reshape the obstacle’s form. The thermodynamics is described by a higher-order temperature-dependent polynomial, avoiding the large errors of the constant adiabatic exponent assumption. The chemical reaction of stoichiometric premixed hydrogen-air is modelled by means of a one-step kinetics with a variable pre-exponential factor. This factor is adapted to reproduce the induction time of a complex kinetics model. The optimisation results in a 5% decrease of the incident shock wave threshold for the successful detonation initiation.

Integrated Vehicle Comparison of Turbo-Ramjet Engine and Pulsed Detonation Engine

2002 ◽  
Vol 125 (1) ◽  
pp. 257-262 ◽  
Author(s):  
T. Kaemming
Keyword(s):  
Life Cycle Cost ◽  
High Speed ◽  
Fuel Efficiency ◽  
Pressure Rise ◽  
Propulsion System ◽  
Cross Sectional ◽  
Pulsed Detonation Engine ◽  
Pulsed Detonation ◽  
Large Matrix ◽  
Detonation Engine

The pulsed detonation engine (PDE) is a unique propulsion system that uses the pressure rise associated with detonations to efficiently provide thrust. A study was conducted under the direction of the NASA Langley Research Center to identify the flight applications that provide the greatest potential benefits when incorporating a PDE propulsion system. The study was conducted in three phases. The first two phases progressively screened a large matrix of possible applications down to three applications for a more in-depth, advanced design analysis. The three applications best suited to the PDE were (1) a supersonic tactical aircraft, (2) a supersonic strike missile, and (3) a hypersonic single-stage-to-orbit (SSTO) vehicle. The supersonic tactical aircraft is the focus of this paper. The supersonic, tactical aircraft is envisioned as a Mach 3.5 high-altitude reconnaissance aircraft with possible strike capability. The high speed was selected based on the perceived high-speed fuel efficiency benefits of the PDE. Relative to a turbo-ramjet powered vehicle, the study identified an 11% to 21% takeoff gross weight (TOGW) benefit to the PDE on the baseline 700 n.mi. radius mission depending on the assumptions used for PDE performance and mission requirements. The TOGW benefits predicted were a result of the PDE lower cruise specific fuel consumption (SFC) and lower vehicle supersonic drag. The lower vehicle drag resulted from better aft vehicle shaping, which was a result of better distribution of the PDE cross-sectional area. The reduction in TOGW and fuel usage produced an estimated 4% reduction in life cycle cost for the PDE vehicle. The study also showed that the simplicity of the PDE enables concurrent engineering development of the vehicle and engine.

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