Query: cfd analysis of nozzle with channels

title: Effect of injection angle of primary and secondary holes on the mixing and combustion in a can type combustor using CFD
abstract: Combustion is one of the vital process in power generation system and so is the combustor in a Gas Turbine. The performance of combustor has greater impact on the efficiency of the cycle, as a result combustor has always been on the prime focus for researchers to improve the efficiency of gas turbine. The present study is focused on numerical analysis, using ANSYS FLUENT, of combustion performance using slotted swirler with swirl angle of 45deg. In this study, considering the importance of primary and dilution injection on combustion performance, the injection angle is varied 60deg to 60deg from normal to the liner wall. Furthermore, the curvature of primary and dilution hole is formed in the form of nozzle and diffuser having convergence and divergence angle of 30deg and 45deg. Because of high swirling effect (S 1.32) RSM (7 equations) turbulence model is used along with Non Premixed combustion mechanism by generating b PDF table. The performance is determined by the mass fraction of CO2 at outlet. Higher the mass fraction of CO2 at outlet, signifies better combustion. From the study it is reflected that the slotted swirler have better combustion performance than non slotted swirler whereas variation of injection angle suggests, injection at 30deg clockwise is more suitable. Also, primary injection done through nozzle channel (convergence angle of 45deg) and dilution injection through diffuser channel (divergence angle of 45deg) results in most efficient combustion performance.

title: Computational Fluid Dynamics Analysis of Stove Systems for Cooking and Drying of Muga Silk
abstract: In India, Silk industry plays an important part in textile industry. Muga silk, the golden yellow silk is quite unique to Assam, North east India where its production is regarded as an important tool for economic development. But, outdated manufacturing technology is followed during the silk production in Assam. The existing cooking process of silk cocoons consists of boiling of silk cocoons in a stainless steel vessel along with water and soda in an open fireplace which is highly energy inefficient. Therefore, two modified systems have been designed; one having cylindrical boiling chamber (vessel) and the other having spherical boiling chamber (vessel) Both the chambers are having a cocoon heating chamber associated with them for cooking and drying of silk cocoons simultaneously. These designs are further classified into two types of designs based on channel and nozzle type combustion chambers. Therefore, the main objective of this paper is to improve the existing designs to maximize the utilization of heat carried by the combustion gases. These modified systems are analysed by using Computational Fluid Dynamics (CFD) selecting standard k ie model. From the analysis, it is seen that these new systems having nozzle type combustion chambers are more efficient than the systems having cylindrical combustion chambers and if these systems are used in silk production, it will be very beneficial for the silk industry as well as for our society.

title: Ex Core CFD Analysis Results for the Prometheus Gas Reactor
abstract: This paper presents the initial nozzle to nozzle (N2N) reactor vessel model scoping studies using computational fluid dynamics (CFD) analysis methods. The N2N model has been solved under a variety of different boundary conditions. This paper presents some of the basic hydraulic results from the N2N CFD analysis effort. It also demonstrates how designers were going to apply the analysis results to modify a number of the design features. The initial goals for developing a preliminary CFD N2N model were to establish baseline expectations for pressure drops and flow fields around the reactor core. Analysis results indicated that the averaged reactor vessel pressure drop for all analyzed cases was 46.9 kPa ~6.8 psid) In addition, mass flow distributions to the three core fuel channel regions exhibited a nearly inverted profile to those specified for the in core thermal/hydraulic design. During subsequent design iterations, the goal would have been to modify or add design features that would have minimized re.

title: Flow Field Characteristics of Multiple Impinging Tapered Nozzles in Confined Channels for High Heat Flux Applications
abstract: Impingement cooling with different tested fluids has been widely accepted and used to dissipate high transient and steady state localized heat loads. There are a plethora of advantages of direct impingement cooling over traditional cooling methods but till date the most alluring advantage is that of the boundary layer thickness proximity to the stagnation region being very small and consequentially leads to very high heat transfer rates. A numerical parametric setup involving 60 differing CFD simulations for a direct on die multiple jet impingement in confined channels in the absence of phase change has been modeled for removing high heat fluxes emanating from the surface of die. The varying parameters for impingement setup includes Reynolds number (8000 Re 20000) based on the main inlet nozzle diameter, the nozzle jet orifice plate to the die (z/d) standoff (up to sixteen nozzle jet diameters distance) nozzle type, number of nozzles and aspect ratio. It is found for the higher aspect ratio tapered nozzle, the junction temperature of the silicon decreases 10deg C 20deg C depending on the Reynolds number regime of the flow. Surface Nusselt number, a dimensionless heat transfer ratio is investigated on the surface of the die along with heat transfer coefficient (h) and it is shown that h increases with aspect ratio increase in the tapered nozzle and/or Reynolds number increase, and decreases with the tapered jet to target standoff distance. The fluid flow pattern reveals interesting features including a boundary layer separation point. The variation of secondary re circulation zone downstream of the stagnation point with a Reynolds number increase is being investigated in Ansys Icepak, the commercial CFD package. A k model was used to predict the turbulent flow and associated characteristics. The findings from this investigation can improve the jet impingement design factors and performance of direct on die impingement for high power density packages. The main objective of the present research is to gain insights computationally into the design and analysis of tapered micro nozzled jet impingement cooling for high power density packages so that robust and efficient impingement systems can be built for prototyping.

title: Regenerative cooling analysis of oxygen/methane rocket engines
abstract: Methane is a promising propellant for future liquid rocket engines. In the cooling channels of a regeneratively cooled engine, it would be close to the critical point. This results in drastic changes in the fluid properties, which makes cooling analysis a challenge. This thesis describes a two pronged approach to tackle this problem. Simple and fast engineering tools allow for the development of insight in the design space using rapid iterations and parametric analyses. However, they are often rather inaccurate. In contrast, detailed multi dimensional tools for numerical analysis are more accurate, but they require more computation time. Both approaches are developed for the analysis of regenerative cooling channels of oxygen/methane engines. Each approach uses complex but accurate models for the thermodynamic and transport properties of methane. OMECA (short for One dimensional Methane Engine Cooling Analysis) is a one dimensional tool that was developed in Python from scratch. This tool divides a nozzle into stations and analyses the one dimensional thermal equilibrium at each station. It makes extensive use of semi empirical equations to calculate the heat transfer at both the hot gas side and the coolant side. The tool is compared to a coupled multi physics analysis tool, showing that the accuracy of the wall temperature is rather poor, with discrepancies of up to 150~K. Both at the hot gas and coolant side, large deviations are present. However, if the input heat flux is correct, OMECA predicts the coolant pressure drop and temperature rise with a 10% accuracy. To obtain a higher accuracy at the coolant side, the open source CFD package OpenFOAM is adapted for analysis of supercritical methane. Of particular note is the custom library that interpolates the fluid property tables at runtime. The selected solver is applicable to steady state compressible flows. The software is then systematically validated using three validation cases. With experimental validation data obtained through cooperation with CIRA, an accuracy of 15 K for the wall temperature prediction is demonstrated. The pressure drop is predicted within 10% Traditionally, the launcher industry uses copper alloys as wall material in regeneratively cooled combustion chambers. They offer a high allowable temperature and high thermal conductivity, but are also heavy and expensive. Recently, several companies have demonstrated aluminium combustion chambers. Aluminium alloys have weight and cost advantages, but have lower allowable temperature and thermal conductivity. The developed tools for cooling analysis are therefore employed to compare aluminium and copper for a generic 10~kN combustion chamber. It is discovered that a thermal barrier coating must be employed to protect the hot gas side of an aluminium combustion chamber, otherwise regenerative cooling is not feasible. Even with such a coating, the pressure drop required to cool the coated aluminium chamber is three times higher than the pressure drop required for a copper chamber. A difference in pressure drop has effects on the vehicle level. A larger pressure drop in the cooling channel of a rocket engine necessitates a higher feed pressure. For a pressure fed engine, this means the tank must be stronger and heavier. It is found that even at modest fuel mass, the increase in tank mass is eight times as large as the decrease in engine mass offered by aluminium. This shows that using aluminium for the chamber wall is not advantageous with respect to copper for a pressure fed, regeneratively cooled, oxygen/methane rocket engine.

title: 3D CFD Calculation of Injector Nozzle Model Flow for Standard and Alternative Fuels
abstract: In this work multi phase flow and erosion analysis were done via simulations in AVL's Workflow Manager with FIRE Solver CFD application, for standard diesel and two alternative biofuels, FAME and DME, inside different nozzle models and with various boundary conditions. Driving force for fluid flow is static pressure difference between inlet and outlet. Analysis criteria were: phase volume fraction distribution due to cavitation, mass flow rate, absolute velocity profile vs. nozzle model narrow channel height and erosion MDPR. Nozzle model consists of narrow channel with sharp (type I) or rounded (type Y) inlet section, with or without downstream placed target, so there was a total of four different model geometries. Simulation results showed that cavitation was present in almost all cases and that clear difference between three observed fuels can be seen. Mass flow in channel type I was lower than one in channel type Y. When comparing three observed fuels, it was noticed that DME fuel usually had highest velocity, but lowest mass flow rate. Contrary to DME, FAME fuel showed highest mass flow rate despite lowest velocity. When designing fuel nozzles, cavitation and cavitation erosion should always be considered. Nozzles in which less cavitation occured, achieved higher mass flow rates for same boundary conditions. When comparing simulation results and physical properties of observed fuels, it can be concluded that density is a leading term in determining mass flow rate. Also, erosion model predicts more intensive MDPR value near narrow channel exit.

title: Numerical Analysis of Partial Admission Flow in an Industrial Steam Turbine
abstract: A partially admitted control stage is a typical feature of an industrial steam turbine. Its purpose is to provide efficient part load operation and to reduce losses caused by an adverse blade height to tip gap ratio by closing segmental arcs of the inlet annulus. On the other hand partial admission naturally causes circumferential nonuniformity of the flow, because the flow enters the control stage rotor over only a portion of the annulus. This induces not only unsteady blade forces but also additional losses in comparison to a full admission turbine. So the advantage of partial admission is reduced. In order to analyze partial admission flow effects a 3D CFD model of an industrial steam turbine needs to be developed. It consists of three parts: i) The nozzle groups covering only a portion of the annulus and the rotor of the impulse type control stage, ii) a cross over channel directing the flow to a reduced diameter, and iii) the downstream reaction type turbine stages. The results show considerable flow nonuniformity downstream of the cross over channel which affects performance of the adjacent full admission stages. Different operating points of the turbine are investigated. Circumferential periodicity is utilized to minimize computational cost of the simulation. Customary guidelines to CFD simulation are taken into account and simulation parameters are carefully checked for their influence on the results: turbulence models, meshing parameters and boundary conditions are varied. The influence of gap flow is checked. The results are finally compared to experimental data to check simulation quality.

title: Finite element analysis of chamber structure's influence on fluidic gyroscope performance
abstract: In this paper,the airflow of two different chamber structures is analyzed contrastively in the sensitive element of fluidic gyroscopes.Using ANSYS FLOTRAN CFD software,the finite element simulation is conducted by a series of procedures,such as two dimensional model building of fluidic gyroscope,meshing,loads applying and equation solving.The two dimensional airflow distributions of rectangle chamber and streamline chamber in sensitive element of fluidic gyroscope are calculated.The results show that the airflow velocity of the exit section in the streamline chamber which is 28.87% of the nozzle velocity is higher than that in the rectangle chamber structure,so the streamline chamber structure brings airflow together to a certain extent;it also reduces the airflow accumulation in the chamber and smoothes airflow within the loop channel;velocity gradient change in the streamline chamber is greater than that in the rectangle chamber,so the temperature changes greatly and the resolution of fluidic gyroscope is better than that with rectangle chamber.

title: Effect of Injector Nozzle Design on Spray Characteristics for Hydrogen Direct Injection Engine Conditions
abstract: Hydrogen has a unique flammability property compared to other fuels. Previous researches proved that direct injection is the most suitable method for this particular fuel. This research aims to study the effect of injector nozzle geometry on mixture and internal combustion efficiency in four stroke automotive engine which operates using hydrogen fuel. The research will concentrate on two aspects, namely the inflow and outflow profile of the injector nozzle. For each flow profile, the effect of geometrical design of the nozzle on the parameter such as flow velocity, fuel penetration distance, average mass fuel consumption and diffusion will be studied in detail. In this study, numerical simulation analysis was done by using the computing fluid dynamics (CFD) software, Star CCM+ Models comprise of multiple orifice nozzle geometry with single angle orifice and double angle orifice was developed with CAD software. A suitable design for a better mixing nozzle would then be determined. Nozzle which possesses a high number of orifice and a smaller diameter will result in a higher flow velocity in the cavity nozzle channel. Geometry of nozzle with different angle of orifice was found to be the most suitable due to the low flow penetration distance and fuel consumption as well as combustion enhancement by the diffusion rate.

title: Research to Break Oil Shale with High Pressure Water Jet Based on Bionic Nozzle
abstract: Oil shale is a sedimentary rock, it is increasingly attracting widespread attention as petroleum supplement energy. Using borehole hydraulic mining techniques to mine oil shale seams at a certain depth in the underground, first and foremost is the use of high pressure water jet to make the overall oil shale ore broken into small pieces and peel them off parent rock. Based on the bionic theories, to design the bionic nozzles are adding several bionic units in the internal flow channel surface of the nozzle, it makes the original smooth flow channel inside the nozzle has become bionic non smooth surface structure, to some extent, effectively improved the hydraulic characteristics of the nozzle internal flow channel, and reduced the flow resistance of the water. Based on CFD simulation and analysis, the reasons for upgrading effect of the crushed oil shale by the bionic nozzle high pressure water jet are analyzed. Experiments show that, in the same working conditions, bionic nozzle compared with the normal nozzle of the same structure parameters, the diameter of the erosion and crushing pit on oil shale samples expanded 4 mm, and the crushing pit depth deepened 3.8 mm using bionic nozzle.