One-dimensional mathematical model of the combustion chamber of a hydrogen/air hypersonic ramjet

1997 ◽  
Vol 32 (1) ◽  
pp. 123-130 ◽  
Author(s):  
A. N. Kraiko ◽  
V. E. Makarov
Keyword(s):  
Mathematical Model ◽  
Combustion Chamber ◽  
One Dimensional

A Numerical Study of Coupling of Thermal and Hydrodynamic Oscillations in a Hybrid Rocket Motor

2011 ◽  
Author(s):  
K. M. Akyuzlu ◽  
K. Albayrak
Keyword(s):  
Mathematical Model ◽  
Combustion Chamber ◽  
Numerical Study ◽  
Rocket Motor ◽  
Propulsion System ◽  
Working Fluid ◽  
Hybrid Rocket ◽  
One Dimensional ◽  
Rocket Propulsion ◽  
Hybrid Rocket Motor

A one-dimensional, mathematical model is adopted to investigate, numerically, the instabilities experienced inside a hybrid rocket propulsion system. The presumption is that such oscillations feed into combustion instabilities and result in poor performance of the propulsion system and/or result in mechanical vibrations that lead to failure of the rocket motor. The model adopted for the numerical study is a one-dimensional, multi-node representation of a subscale hybrid rocket propulsion system. A one dimensional channel with circular cross-section is configured to simulate a combustion chamber of a rocket hybrid rocket motor and is connected to a converging–diverging nozzle in the downstream and to a plenum with a flow straightener in the upstream side. The working fluid is supplied from a pressurized storage tank to the upstream plenum through a throttle valve. A multi-component approach is used to model, mathematically, the propulsion system. In this integrated-component model, the unsteady flow through the throttle valve and the nozzle is assumed to be one-dimensional and isentropic whereas the flow in the forward plenum and in the combustion chamber is assumed to be a one-dimensional, unsteady, compressible, turbulent, and subsonic. The physics based mathematical model of the flow in the channel consists of conservation of mass, momentum and energy equations subject to appropriate boundary conditions as defined by the physical problem stated above. The working fluid is assumed to be compressible through a simple ideal gas relation. The governing equations of the compressible flow in the combustion chamber are discretized using the second order accurate MacCormack finite difference scheme. Convergence and grid independence studies were done to determine the optimum mesh size and computational time increment needed for the present simulations. Furthermore, steady state results of the proposed model are compared to the results of the isentropic, Fanno (viscous 1-D flow), and Rayleigh (1-D flow with heat input) case studies to verify the accuracy of the numerical predictions. Numerical experiments were then carried out to simulate the flow oscillations in the combustion chamber of a sample subscale hybrid rocket motor. Experiments were repeated for various operating conditions (Re numbers between 104 and 106) to determine the flow regions where these oscillations are sustained. The numerical simulation results indicate that the proposed mathematical model predicts the expected unsteady axial distributions of temperature, velocity, and pressure in the combustion chamber and the general characteristics of the experimentally observed instabilities associated with hybrid rocket propulsion systems.

Using Tolerance-Maps to Generate Frequency Distributions of Clearance and Allocate Tolerances for Pin-Hole Assemblies

2007 ◽  
Vol 7 (4) ◽  
pp. 347-359 ◽  
Author(s):  
Gaurav Ameta ◽  
Joseph K. Davidson ◽  
Jami J. Shah
Keyword(s):  
Mathematical Model ◽  
Statistical Method ◽  
Frequency Distribution ◽  
Probabilistic Representation ◽  
Worst Case ◽  
Frequency Distributions ◽  
One Dimensional ◽  
Material Condition ◽  
Geometric Tolerances ◽  
Case Basis

A new mathematical model for representing the geometric variations of lines is extended to include probabilistic representations of one-dimensional (1D) clearance, which arise from positional variations of the axis of a hole, the size of the hole, and a pin-hole assembly. The model is compatible with the ASME/ ANSI/ISO Standards for geometric tolerances. Central to the new model is a Tolerance-Map (T-Map) (Patent No. 69638242), a hypothetical volume of points that models the 3D variations in location and orientation for a segment of a line (the axis), which can arise from tolerances on size, position, orientation, and form. Here, it is extended to model the increases in yield that occur when maximum material condition (MMC) is specified and when tolerances are assigned statistically rather than on a worst-case basis; the statistical method includes the specification of both size and position tolerances on a feature. The frequency distribution of 1D clearance is decomposed into manufacturing bias, i.e., toward certain regions of a Tolerance-Map, and into a geometric bias that can be computed from the geometry of multidimensional T-Maps. Although the probabilistic representation in this paper is built from geometric bias, and it is presumed that manufacturing bias is uniform, the method is robust enough to include manufacturing bias in the future. Geometric bias alone shows a greater likelihood of small clearances than large clearances between an assembled pin and hole. A comparison is made between the effects of choosing the optional material condition MMC and not choosing it with the tolerances that determine the allowable variations in position.

Infiltration in Unsaturated Frozen Soil

1984 ◽  
Vol 15 (4-5) ◽  
pp. 243-252 ◽  
Author(s):  
Helén Engelmark
Keyword(s):  
Mathematical Model ◽  
Simulated Data ◽  
Frozen Soil ◽  
Thermal Parameters ◽  
Field Observations ◽  
Snow Melt ◽  
One Dimensional ◽  
Run Off ◽  
Melt Infiltration

A one-dimensional mathematical model is used to simulate the process of snow-melt infiltration in unsaturated frozen silt. Hydraulic and thermal parameters are mainly based on data given in the literature. Field observations in a watershed (of area 1.8 km2) are compared with simulated data and consequences on snow melt run-off are discussed.

scholarly journals Development of One-Dimensional Mathematical Model for Validation of Pulse Diagnosis

2008 ◽  
Vol 74 (737) ◽  
pp. 142-148 ◽  
Author(s):  
Kentaro NARUMI ◽  
Tsutomu NAKANISHI ◽  
Atsushi SHIRAI ◽  
Toshiyuki HAYASE
Keyword(s):  
Mathematical Model ◽  
Pulse Diagnosis ◽  
One Dimensional

scholarly journals Modeling a fuel injector for a two-stroke diesel engine

2017 ◽  
Vol 170 (3) ◽  
pp. 147-153
Author(s):  
Rafał SOCHACZEWSKI ◽  
Zbigniew CZYŻ ◽  
Ksenia SIADKOWSKA
Keyword(s):  
Diesel Engine ◽  
Combustion Chamber ◽  
Fuel Injection ◽  
Maximum Load ◽  
Fuel Injector ◽  
Dimensional Model ◽  
Flow Area ◽  
Fuel Mass ◽  
One Dimensional ◽  
Injector Nozzle

This paper discusses the modeling of a fuel injector to be applied in a two-stroke diesel engine. A one-dimensional model of a diesel injector was modeled in the AVL Hydsim. The research assumption is that the combustion chamber will be supplied with one or two spray injectors with a defined number of nozzle holes. The diameter of the nozzle holes was calculated for the defined options to provide a correct fuel amount for idling and the maximum load. There was examined the fuel mass per injection and efficient flow area. The studies enabled us to optimize the injector nozzle, given the option of fuel injection into the combustion chamber to be followed.

Possibility of Evaluating a Depth of Defects as a Hole in a Composite Dielectric Sample by the Parameters of Electric Response to Pulse Mechanical Excitation

2018 ◽  
Vol 781 ◽  
pp. 155-158 ◽  
Author(s):  
Petr Khorsov ◽  
Anatoly Surzhikov ◽  
Vladimir Surzhikov ◽  
Roman Laas
Keyword(s):  
Mathematical Model ◽  
Electromagnetic Response ◽  
Electric Response ◽  
One Dimensional ◽  
Response Parameter ◽  
Dielectric Sample ◽  
Receiver System ◽  
Mechanoelectrical Transformations ◽  
Spurious Component ◽  
The One

The applicability of the method mechanoelectrical transformations (MET) to determine the depth of the macrodefects location in the sample on parameters of the electromagnetic response is evaluated. As the response parameter it was used the phase characteristic of the signal analytical representation.On the one-dimensional mathematical model it was shown the possibility to detect phase response changes when reflected from defect acoustic wave is mixed with the signal spurious component generated by a distributed MET sources. Experimental verification of mathematical model on a sample of concrete was conducted. It has been shown that the sensitivity of the method MET to evaluation of the macrodefect locate depth depends on the wavelength of the excitation pulse and the area of the macrodefect border closest to the emitter-receiver system.

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