@article{
 title = {Load Oscillations Caused by Unstart of Hypersonic Wind Tunnels and Engines},
 type = {article},
 year = {1998},
 volume = {14},
 websites = {http://arc.aiaa.org},
 id = {ac184be3-a5c2-3750-9578-eca1a89e8ce4},
 created = {2021-05-31T23:14:20.156Z},
 accessed = {2021-05-31},
 file_attached = {true},
 profile_id = {6476e386-2170-33cc-8f65-4c12ee0052f0},
 group_id = {5a9f751c-3662-3c8e-b55d-a8b85890ce20},
 last_modified = {2021-05-31T23:14:24.983Z},
 read = {false},
 starred = {false},
 authored = {false},
 confirmed = {false},
 hidden = {false},
 citation_key = {shimura:jpp:1998},
 private_publication = {false},
 abstract = {Large-amplitude load oscillations were observed during the tests of a hypersonic engine model in a freejet-type wind tunnel. To clarify the cause of the oscillations and their characteristics, oscillating wall pressures and loads on a drag model and engine models were investigated. Floww eld was observed by shadowgraph to determine the cause of the large starting loads. Power spectral density functions and probability functions of wall pressures and loads were derived by the fast Fourier transform. The amplitude of the unsteady frontal pressure was correlated with the dynamic pressure. The magnitude of the starting load was related to the drag coeff cient of the models, and the expected maximum peak loads of a large-scale ramjet engine test facility were evaluated. Engine unstart loads were also simulated by means of secondary ow injection into a small-scale model of a ramjet engine. With these methods, characteristics of engine unstart loads and the possibility of sensing engine unstart in its early phase were studied. Engine unstart could be sensed with pressure measurement around the engine throat before it became severe. Furthermore, engine unstart loads associated with scramjet engine combustion were related to the drag coeff cient of the engine. Nomenclature A f = frontal area of test piece C d = drag coeff cient, F d /Af/q C dp = peak load coeff cient, F u /Af/q F d = drag without fuel injection F p = pressure drag, A f P 20 F u = peak value of unsteady loads caused by unstart of engines or wind tunnels M = Mach number P(x) = cumulative probability distribution function, time interval with X AC x in total sampling time, ProbXAC x P 0 = nozzle total pressure P 20 = frontal pressure, pitot pressure q = dynamic pressure of freejet X ¯ = mean value of X(t) X AC = X(t) X ¯ X(t) = time-dependent sample functions = standard deviation of X AC},
 bibtype = {article},
 author = {Shimura, Takashi and Mitani, Tohru and Sakuranaka, Noboru and Izumikawa, Muneo},
 doi = {10.2514/2.5287},
 journal = {Journal of Propulsion and Power},
 number = {3}
}

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To clarify the cause of the oscillations and their characteristics, oscillating wall pressures and loads on a drag model and engine models were investigated. Floww eld was observed by shadowgraph to determine the cause of the large starting loads. Power spectral density functions and probability functions of wall pressures and loads were derived by the fast Fourier transform. The amplitude of the unsteady frontal pressure was correlated with the dynamic pressure. The magnitude of the starting load was related to the drag coeff cient of the models, and the expected maximum peak loads of a large-scale ramjet engine test facility were evaluated. Engine unstart loads were also simulated by means of secondary ow injection into a small-scale model of a ramjet engine. With these methods, characteristics of engine unstart loads and the possibility of sensing engine unstart in its early phase were studied. Engine unstart could be sensed with pressure measurement around the engine throat before it became severe. Furthermore, engine unstart loads associated with scramjet engine combustion were related to the drag coeff cient of the engine. Nomenclature A f = frontal area of test piece C d = drag coeff cient, F d /Af/q C dp = peak load coeff cient, F u /Af/q F d = drag without fuel injection F p = pressure drag, A f P 20 F u = peak value of unsteady loads caused by unstart of engines or wind tunnels M = Mach number P(x) = cumulative probability distribution function, time interval with X AC x in total sampling time, ProbXAC x P 0 = nozzle total pressure P 20 = frontal pressure, pitot pressure q = dynamic pressure of freejet X ¯ = mean value of X(t) X AC = X(t) X ¯ X(t) = time-dependent sample functions = standard deviation of X AC","bibtype":"article","author":"Shimura, Takashi and Mitani, Tohru and Sakuranaka, Noboru and Izumikawa, Muneo","doi":"10.2514/2.5287","journal":"Journal of Propulsion and Power","number":"3","bibtex":"@article{\n title = {Load Oscillations Caused by Unstart of Hypersonic Wind Tunnels and Engines},\n type = {article},\n year = {1998},\n volume = {14},\n websites = {http://arc.aiaa.org},\n id = {ac184be3-a5c2-3750-9578-eca1a89e8ce4},\n created = {2021-05-31T23:14:20.156Z},\n accessed = {2021-05-31},\n file_attached = {true},\n profile_id = {6476e386-2170-33cc-8f65-4c12ee0052f0},\n group_id = {5a9f751c-3662-3c8e-b55d-a8b85890ce20},\n last_modified = {2021-05-31T23:14:24.983Z},\n read = {false},\n starred = {false},\n authored = {false},\n confirmed = {false},\n hidden = {false},\n citation_key = {shimura:jpp:1998},\n private_publication = {false},\n abstract = {Large-amplitude load oscillations were observed during the tests of a hypersonic engine model in a freejet-type wind tunnel. To clarify the cause of the oscillations and their characteristics, oscillating wall pressures and loads on a drag model and engine models were investigated. Floww eld was observed by shadowgraph to determine the cause of the large starting loads. Power spectral density functions and probability functions of wall pressures and loads were derived by the fast Fourier transform. The amplitude of the unsteady frontal pressure was correlated with the dynamic pressure. The magnitude of the starting load was related to the drag coeff cient of the models, and the expected maximum peak loads of a large-scale ramjet engine test facility were evaluated. Engine unstart loads were also simulated by means of secondary ow injection into a small-scale model of a ramjet engine. With these methods, characteristics of engine unstart loads and the possibility of sensing engine unstart in its early phase were studied. Engine unstart could be sensed with pressure measurement around the engine throat before it became severe. Furthermore, engine unstart loads associated with scramjet engine combustion were related to the drag coeff cient of the engine. Nomenclature A f = frontal area of test piece C d = drag coeff cient, F d /Af/q C dp = peak load coeff cient, F u /Af/q F d = drag without fuel injection F p = pressure drag, A f P 20 F u = peak value of unsteady loads caused by unstart of engines or wind tunnels M = Mach number P(x) = cumulative probability distribution function, time interval with X AC x in total sampling time, ProbXAC x P 0 = nozzle total pressure P 20 = frontal pressure, pitot pressure q = dynamic pressure of freejet X ¯ = mean value of X(t) X AC = X(t) X ¯ X(t) = time-dependent sample functions = standard deviation of X AC},\n bibtype = {article},\n author = {Shimura, Takashi and Mitani, Tohru and Sakuranaka, Noboru and Izumikawa, Muneo},\n doi = {10.2514/2.5287},\n journal = {Journal of Propulsion and Power},\n number = {3}\n}","author_short":["Shimura, T.","Mitani, T.","Sakuranaka, N.","Izumikawa, M."],"urls":{"Paper":"https://bibbase.org/service/mendeley/6476e386-2170-33cc-8f65-4c12ee0052f0/file/7529d42b-9e21-b96d-1700-ba89dbacaf34/Shimura_et_al___Unknown___Load_Oscillations_Caused_by_Unstart_of_Hypersonic_Wind_Tunnels_and_Engines.pdf.pdf","Website":"http://arc.aiaa.org"},"biburl":"https://bibbase.org/service/mendeley/6476e386-2170-33cc-8f65-4c12ee0052f0","bibbaseid":"shimura-mitani-sakuranaka-izumikawa-loadoscillationscausedbyunstartofhypersonicwindtunnelsandengines-1998","role":"author","metadata":{"authorlinks":{}}},"bibtype":"article","biburl":"https://bibbase.org/service/mendeley/6476e386-2170-33cc-8f65-4c12ee0052f0","dataSources":["qwkM8ZucCwtxbnXfc","ya2CyA73rpZseyrZ8","2252seNhipfTmjEBQ"],"keywords":[],"search_terms":["load","oscillations","caused","unstart","hypersonic","wind","tunnels","engines","shimura","mitani","sakuranaka","izumikawa"],"title":"Load Oscillations Caused by Unstart of Hypersonic Wind Tunnels and Engines","year":1998}