Unsteady pressure behavior in a ramjet/scramjet inlet

Rodi, Patrick E.; Emami, Saied; Trexler, Carl A.

doi:10.2514/3.24061

Cited by 102 publications

(17 citation statements)

References 4 publications

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“…Some useful conclusions were obtained, but due to the insufficiency of dynamic pressure gauges and the lack of flow visualization, the unsteady flow pattern of a hypersonic inlet is still obscure. What's worse, even the authors of [13] are not sure whether the observed unsteady pressure behavior is the result of noisy measurements. As to the flow pattern of unstarted supersonic inlets, many papers have discussed the buzz phenomena and analyzed the possible oscillatory mechanisms, which are not agreed upon even at present [14][15][16].…”

Section: Introductionmentioning

confidence: 83%

“…Unfortunately, several papers have focused on the flow pattern of unstarted hypersonic inlets [10][11][12] and dealt with this phenomena mainly in a steady manner, which blurs its oscillatory nature and diminishes its possible threat artificially. In [13], the mean and time-accurate pressures in a two-dimensional hypersonic inlet were measured both under a backpressure-induced unstart condition and under a cowlinduced unstart condition. Some useful conclusions were obtained, but due to the insufficiency of dynamic pressure gauges and the lack of flow visualization, the unsteady flow pattern of a hypersonic inlet is still obscure.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Study of the Unstable-Unstarted Condition of a Hypersonic Inlet at Mach 6

Tan

Guo

2007

Journal of Propulsion and Power

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Wind-tunnel tests were conducted to better understand the flow pattern of a hypersonic inlet at an unstableunstarted condition that is caused by the downstream mass flow choking. High-speed shadowgraph flow visualization and instantaneous pressure measurements are employed to reveal the oscillations of the shock system and the unsteady process of the duct flow. Results show that the shock system both inside and in front of the inlet duct oscillates intermittently when the inlet is unstarted. With the increase of the downstream throttling ratio, the fundamental frequency of the unsteady flow process goes up and the shock-on-lip time goes down, but the process whereby the shock system is disgorged and swallowed remains unchanged, lasting for 15 ms. When the throttling ratio is 89 and 91%, the fundamental frequency is 8 and 23 Hz, respectively. At the smaller throttling ratio, the aerodynamic oscillatory phenomenon of the inlet can be divided into three stages: namely, mass filling up, shock system disgorging and swallowing, and near-throat flow pattern establishing and backpressure propagating. At the larger throttling ratio, the first stage disappears and the third one shortens.

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Section: Introductionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Unstable-Unstarted Condition of a Hypersonic Inlet at Mach 6

Tan

Guo

2007

Journal of Propulsion and Power

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“…In scramjet environments, an array of high-speed pressure transducers have been used to study the pressure field within inlet/isolators during unstart. 20,21 In neither investigation, however, was there an attempt to utilize the measurements as part of an isolator shock-position-control sensor.…”

Section: Introductionmentioning

confidence: 99%

High-Frequency Pressure Measurements for Unstart Detection in Scramjet Isolators

Donbar¹,

Linn²,

Afb³

et al. 2010

46th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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This paper describes an experimental investigation using an array of high-frequency pressure transducers located in the isolator/combustor region of a direct-connect hydrocarbon-fueled, scramjet combustor. Isolator/combustor entrance conditions were fixed and representative of a Mach-5.5 flight condition. Mean, standard deviation, and spectral content of measured pressures were similar to those measured in previous studies. A simple model relating the sum of measured pressures and the fuel flow rate delivered to the primary injectors was developed. Pressure measurements were post-processed and evaluated for use in a shock-position-control sensor to detect engine unstart. Four methods of post-processing the pressure data and corresponding detection criteria were evaluated: a) 150% pressure rise, b) 150% increase in standard deviation, c) 150% increase in power spectral density (PSD), and d) summation of pressures. Pressure summation typically provided 1-2 s more lead time in detecting unstart then any other method.

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“…The engine used in projectile is composed of inlet, gas generator, secondary firebox and nozzle. The function of the ramjet engine inlet is to switch the kinetic energy to potential energy and raise the pressure of the gas stream using the velocity in front of it, and provide the airflow the engine needed [1]- [3]. The application research of the inlet used in aero engine is mature, but there are also some tasks to research in applying it on the ramjet assisted projectile.…”

Section: Introductionmentioning

confidence: 99%

Optimization design for the two-dimensional contour of the ramjet engine inlet

Wang¹,

Jiang²,

Zhou³

2008

2008 Asia Simulation Conference - 7th International Conference on System Simulation and Scientific Computing

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Taking the ramjet extended range projectile as the research subject, in order to improve the total pressure recovery coefficient, the parameter model and numerical simulation to the flow field of inlet have been assembled by the auto-optimization platform, simulated annealing technique has been used to optimize the cone angle of simple cone and double angle cone based on the highest total pressure recovery coefficient. After the optimization, the total pressure recovery coefficient of the inlet had been separately improved 10.2% and 5.1%. The numerical simulation results are better in accord with the test data, and they have the same error direction, it proved that the optimization results are believable. Four diffusion laws including equal divergence angle, equal area ratio, equal Mach number and equal pressure grad have been used separately to design the contour of the inlet expansion section, and the influence of the different diffusion laws to the inlet has been analyzed. The results show that the best angle cone can be found more efficiently through optimizing, and the inlet expansion section of the equal pressure grad has better flow field quality under design conditions.

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Unsteady pressure behavior in a ramjet/scramjet inlet

Cited by 102 publications

References 4 publications

Experimental Study of the Unstable-Unstarted Condition of a Hypersonic Inlet at Mach 6

Experimental Study of the Unstable-Unstarted Condition of a Hypersonic Inlet at Mach 6

High-Frequency Pressure Measurements for Unstart Detection in Scramjet Isolators

Optimization design for the two-dimensional contour of the ramjet engine inlet

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