asghar azimi

The aim of the present research is to obtain the ability to use the cryogenic propellant engines on a laboratory scale. In this regard, it is necessary to build some experimental motors and investigate the their performance parameters. The liquid oxygen as a common oxidizer and ethanol as a green fuel have been selected as propellant components. The engine is designed to produce 400 kgf force at the nominal condition. The pintle type injector has been chosen in which liquid oxygen and fuel are flowed in the axial and radial directions, respectively. The combustion chamber has been protected against overheating by applying the regenerative cooling. However, the laboratory feature of the engine design has provided the using of water instead the cooling propellant. All main components of the engine such as injector, igniter, and flow controllers, are examined by the cold tests. A comprehensive test facility is designed and set up for hot fire tests in which the performance of almost all parameters can be evaluated. Fifteen fire tests have been performed. Maximum obtained pressure and evaluated combustion efficiency were about 75% of design values.

This paper deals with utilization of the network method to fast analysis of the gas turbine combustors. In this method, a combustor is divided into several independent flows by some nodes and interconnecting elements. The fundamental equations which should be satisfied in the network method are conservation equations of mass and energy at each node and the pressure drop-flow rate correlation for each element. These equations constitute a system of equations of flow rate and pressure drop. Solving this system using a set of initial value gives pressure, flow rate, and density at each node that finally leads to a converging solution. The conventional relations for pipes and orifices are used for flow modeling. In order to combustion modeling, equilibrium assumption is applied in the primary and secondary combustion zones. The dilution effect is considered by entering the air from dilution holes into the flow of combustion products. The liner temperature is calculated by considering the effects of convection and radiation in the combustor. By the network method in a can type combustor, at the first step a cold flow analysis is performed and the flow rate and the pressure drop in each element are obtained. In the next step by including the combustion of kerosene and heat transfer, the distribution of flow rates, pressure, temperature, and species concentration of combustion products are calculated. The computation results are compared with the existing experimental data and an excellent agreement is seen. The quality of results and the solution procedure of the problem show that the network method is able to present a costly and accurate analysis to help the combustor designers

The aim of present article is investigation of evaporation of single- and multi-component fuels droplet and study the effect of unsteadiness term on it. Two approaches are used; a fully transient and quasi-steady approaches. The species, momentum, and energy equations for gas phase and species and energy equations for liquid phase are solve numerically by assuming variable properties with respect to temperature. The results obtained from the fully transient approach show an acceptable compliance with experimental data at atmospheric pressure in a wide range of fuel volatility and ambient temperature for the single- and multi-component fuels. Heptane, decane, and hexadecane are used in order to investigate the effects of fuel volatility on evaporation.The steadiness of processes in the gas phase has been checked by using two measures of unsteadiness related to the mass and heat diffusion of fuel vapor on the droplet surface. The deviations of the results of the quasi-steady approach from the fully transient have been justified by the unsteadiness measures. The results show that fuel and ambient temperature have significant effects on the unsteadiness. For heavier fuels and higher ambient temperature, the diviation of quasi- steady approach from fully transient increases. Also the diviation becomes higher when the differences between volatility of component increase. Therefore, it is concluded that the quasi-steady approach presents reasonable results for lighter fuels in the case of single component and whenever the volatilities of components are very close.