Sharif Digital Repository

Rotating detonation engines are capable of reaching a higher efficiency in comparison with ordinary engines, due to utilizing pressure gained combustion wave. In this study, the feasibility of a laboratory sample RDE with an annular geometry of diameter of 76 mm has been studied and then designed and constructed. In this sample, hydrogen and standard air were separately injected into the combustion chamber of detonation. The injection of fuel flow and air flow are axial and radial, respectively. The designed geometry is flexible in terms of changing the injection geometry and detonation channel wide, which provided the possibility of testing for a variety of injection and detonation... 

The purpose of this study is to investigate the efficiency of a flamelet method along with the LES1 approach in the modeling of a turbulent premixed flame behind the bluff-body. In this flame ,because of the high turbulence intensity and fuel dilution, there is a significant interaction between the turbulence and chemical kinetics. In this study, first, the cold flow is modeled using LES and RANS2 approaches. Then, using the Flame-Generated Manifold (FGM) model and a presumed PDF model, the turbulent reacting flow is simulated.Comparison of the results of the LES and RANS showed that the accuracy of the LES method in simulating the physics of turbulent flow is much higher than RANS, but its... 

Up to early seventies, Gas turbine combustor design was very time consuming and costly process including trial and errors through test rigs. Over the time analytical-experimental relationships take place as one of the key rules in the design processes. With the increasing power of computer calculations, computational fluid dynamics find its way in the procedure. Obtaining a deeper understanding of flow conditions and geometry inside the chamber, a great reduction in production time and cost of revisions to rigs and samples were achieved. Finding a precise prediction of polluting elements like NOx (less than 10 ppm) after many run hours and enormous computing resources, CFD methods must... 

This thesis presents turbulent partially premixed combustion modeling behind a bluff-body by using the Flamelet Generated Manifold. The objective of the present work is to develop a 4D FGM program to simulate partially premixed combustion at a reasonable computational cost. Pre-tabulated data of this manifold is obtained by using a correlated joint PDF. An in-house code is developed to build a pre-tabulated library in conjunction with a correlated PDF. Also, an exclusive OpenFOAM solver is created by employing the PIMPLE algorithm. This solver provides the link of the computational domain with the pre-tabulated chemistry. This program is used to simulate Cambridge-Sandia stratified burner... 

By creating constant volume combustion, the rotating detonation chamber increases efficiency compared to conventional constant pressure chambers. The RDC is smaller and mechanically more straightforward than the other detonation chambers, such as the pulse chamber. In the current research, an RDC with an outer diameter of 76 mm and an inner diameter of 64 mm, using hydrogen and air as fuel and oxidizer, has been successfully tested and data collected in the laboratory. Data acquisition has been made by high-frequency and pressure measurement facilities. In the following, the chamber has been optimized and improved by applying parametric studies (equivalence ratio, mass flow rate, channel... 

An a priori analysis is performed to assess the performances of Laminar Flamelet Decomposition (LFD) and Conditional Source-term Estimation (CSE) methods in predicting conditional and unconditional filtered production rates and mass fractions for turbulent premixed flames over a wide range of Karlovitz numbers, which is an indicator for the level of turbulence-chemistry interaction in premixed combustion.In LFD, it is assumed that a turbulent flame is composed of strained laminar flamelets. By presuming the functional form of the probability density function (PDF) of the progress variable and inverting the integral equation for the unconditional filtered mass fractions of one of the species,...