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Wyszukujesz frazę "Mach number" wg kryterium: Temat


Wyświetlanie 1-6 z 6
Tytuł:
A preconditioned solution scheme for the computation of compressible flow in turbomachinery at arbitrary mach numbers
Autorzy:
Anker, J. E.
Mayer, J. F.
Stetter, H.
Powiązania:
https://bibliotekanauki.pl/articles/1986683.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
preconditioning
non-reflecting boundary condition
Mach number independency
turbomachinery flow
Opis:
A preconditioned solution scheme for the computation of compressible flow in turbomachinery at arbitrary Mach numbers is presented. The preconditioning technique used is applied to a state-of-the-art explicit, time-marching Navier-Stokes code which originally was developed for compressible, high-speed turbomachinery applications. It combines the ideas of low Mach number preconditioning and artificial compressibility method into a unified approach where principally fluids with arbitrary equations of state can be simulated. As shown by the test cases presented, it allows the code to simulate flows efficiently and accurately independent of the Mach number. A description of the Navier-Stokes equations for rotating coordinate systems, along with the solution scheme and the details of the preconditioning method is given. Since turbomachinery computations are often performed on truncated domains, the solution scheme should be used in conjunction with non-reflecting boundary conditions. A change in the time-dependency of the equations due to preconditioning necessitates a modification of the boundary conditions. Thus, a derivation of the appropriate boundary conditions for the presented preconditioned scheme was performed and the resultant equations are given in this paper. The effectiveness of the new boundary conditions is demonstrated by comparing them with both boundary conditions that use the standard one-dimensional characteristic approach and the original boundary conditions for the non-preconditioned case.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 1; 143-176
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and validation of a single-jack variable Mach number nozzle in a cryogenic transonic wind tunnel
Autorzy:
Yu, Chengguo
Zhang, Zhili
Wang, Ning
Nie, Xutao
Peng, Qiang
Chen, Zhenhua
Powiązania:
https://bibliotekanauki.pl/articles/2200829.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
cryogenic
flow uniformity
single-jack nozzle
transonic wind tunnel
variable
Mach number
Opis:
The wind tunnel with variable Mach numbers controlled by a single jack is highly desired in the aerospace, automobile and building industry due to its superior controllability and working range. Decreasing the temperature of a test gas is an efficient and economical approach to achieving higher Reynolds numbers that accommodate all working statuses of test subjects, which however, brings new challenges to the wind tunnel design nowadays. This paper proposes a new design concept of a single-jack variable Mach number nozzle based on its particular cryogenic characteristics, as the nozzle is the core structure to achieve variable Mach numbers. The contours of the nozzle under different Reynolds numbers and Mach numbers are modeled and solved by an incomplete elliptic integral, followed by modification with cryogenic characteristics. A 0.3-m cryogenic wind tunnel is utilized as a validation platform for the nozzle design, resulting in designed contours being in line with the measured contours. Moreover, the root means square (RMS) deviations of Mach number 1.3 at the core position are controlled within 0.011 in low and high temperatures, which surpasses the other existing wind tunnels.
Źródło:
Journal of Theoretical and Applied Mechanics; 2022, 60, 4; 719--732
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fuzzy-based prediction for suddenly expanded axisymmetric nozzle flows with microjets
Autorzy:
Quadros, Jaimon D.
Suhas, P.
Khan, Sher A.
Aabid, Abdul
Baig, Muneer
Mogul, Yakub I.
Powiązania:
https://bibliotekanauki.pl/articles/2173710.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
base pressure
Mach number
fuzzy modeling
ciśnienie bazowe
liczba Macha
modelowanie rozmyte
Opis:
The current research focuses on the implementation of the fuzzy logic approach for the prediction of base pressure as a function of the input parameters. The relationship of base pressure (β ) with input parameters, namely, Mach number (M), nozzle pressure ratio (η), area ratio (α), length to diameter ratio (ξ ), and jet control (ϑ ) is analyzed. The precise fuzzy modeling approach based on Takagi and Sugeno’s fuzzy system has been used along with linear and non-linear type membership functions (MFs), to evaluate the effectiveness of the developed model. Additionally, the generated models were tested with 20 test cases that were different from the training data. The proposed fuzzy logic method removes the requirement for several trials to determine the most critical input parameters. This will expedite and minimize the expense of experiments. The findings indicate that the developed model can generate accurate predictions
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 5; art. no. e142654
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nowe rozwiązania środków transportu na przykładzie kolei niskociśnieniowej
The low pressure railway : a new solutions of the means of transport
Autorzy:
Rydzek, Marcin
Powiązania:
https://bibliotekanauki.pl/articles/312450.pdf
Data publikacji:
2019
Wydawca:
Instytut Naukowo-Wydawniczy "SPATIUM"
Tematy:
kolej niskociśnieniowa
Hyperloop
Inductrack
granica Kantrowitza
liczba Macha
low-pressure railway
limit of Kantrowitz
Mach number
Opis:
W pracy przedstawiono przyszłościowy środek lokomocji w postaci technologii kolei niskociśnieniowej - Hyperloop. Opisano stan obecny wdrażanej technologii oraz odniesiono się do problemów związanych prędkościami w tunelu próżniowym, gdzie jednym z podstawowych jest granica Kantrowitza. Montaż turbosprężarek ma temu zapobiec, lecz taka strategia jest zbyt kosztowna. Przedstawiona technologia może stanowić alternatywę dla obecnych środków transportu.
The paper presents a forward-looking means of transport in the form of hyperloop technology. The paper describe current state of the implemented technology and refers to the problems related to speeds in a vacuum tunnel. The basic problem related to speed is the limit of Kantrowitz. The presented technology can be an alternative to the current means of transport.
Źródło:
Autobusy : technika, eksploatacja, systemy transportowe; 2019, 20, 6; 116-119
1509-5878
2450-7725
Pojawia się w:
Autobusy : technika, eksploatacja, systemy transportowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of base pressure behavior in a suddenly expanded duct at supersonic Mach number regimes using statistical analysis
Autorzy:
Quadros, J. D.
Khan, S. A.
Antony, A. J.
Powiązania:
https://bibliotekanauki.pl/articles/122311.pdf
Data publikacji:
2018
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
Mach number
Taguchi
nozzle pressure ratio
area ratio
liczba Macha
eksperyment Taguchi
model regresji liniowej
stosunek powierzchni
Opis:
The present experimental evaluation deals with the behavior of base pressure (BP) in a suddenly expanded duct at supersonic Mach number regimes. The experiments have been conducted for two cases viz. Without and with the use of microjets or active control. The plan of experiments was planned as per Taguchi design of experiments for acquiring data in a controlled manner. An L27 orthogonal array and analysis of variance (ANOVA) has been employed to investigate the contribution (in terms of percentage) of distinct process parameters like Mach number (M), Nozzle Pressure Ratio (N), Area Ratio (A) and their interactions affecting base pressure. The correlation between these parameters affecting base pressure has been obtained using multiple linear regression analysis. It has been concluded that the Mach number and area ratio were the factors that had high statistical significance on the behavior of base pressure for both cases. The performances of the developed linear regression models have been validated for accuracy prediction by use of 15 test cases. The performance of both the base pressure models was found to be better with percentage prediction in deviation lying in the range of –12.92% to +15.88% for base pressure without control and –10.27% to +19.23% for base pressure with control.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2018, 17, 4; 59-72
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analytical dynamic model of coefficient of friction of air pipeline under pressure
Autorzy:
Dmytriv, Vasyl
Dmytriv, Ihor
Horodetskyy, Ivan
Dmytriv, Taras
Powiązania:
https://bibliotekanauki.pl/articles/328390.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
coefficient of friction
Mach number
pressure
aspect ratio
Reynolds number
analytical model
vacuum
współczynnik tarcia
liczba Macha
ciśnienie
współczynnik kształtu
liczba Reynoldsa
model analityczny
próżnia
Opis:
To transport of the air in the pipeline, an analytical model is developed that takes into account the gas velocity, its kinematic and dynamic characteristics - density, viscosity depending on the pressure in a given space of the pipeline. The analytical model makes it possible to calculate the coefficient of friction of gas transportation in the pipeline at intervals of the absolute pressure from 220 to 2 kPa and M < 1 Mach numbers, depending on the diameter and length of the pipeline and physical and technological characteristics of the gas. The K1* aspect ratio is proposed, which characterizes in time the ratio of the dynamic force of movement of gas to the static pressure related to the diameter of the pipeline. The coefficient of air friction was modeled according to the vacuum pressure as a parameter of density and air flow. Air flow was taken from 1.917·10-3 m 3/s to 44.5·10-3 m 3/s respectively, diameters from 0.030 to 0.070 m and Mach number was M = 0.005-0.13. At the vacuum and excess pressures with increasing of Reynolds number and decreasing of Mach number the gas friction coefficient increased linearly. According to the simulation results as the pressure loss and the diameter of the pipeline are increased the friction coefficient increased as well. Analogically, at the vacuum metric pressure when the pressure loss and the diameter of the pipeline are increased the friction coefficient increased. At the pipeline internal diameters of 22, 30, 36 mm accordingly for pressure losses from 2 to 14 kPa the coefficient of air friction varies from 0.006 to 54.527 respectively.
Źródło:
Diagnostyka; 2019, 20, 4; 89-94
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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