The purpose of this paper is to find the optimum design of a typical GAS TURBINE EXHAUST DIFFUSER. In order to access the maximum overall static pressure recovery at the condition of swirling flow, an evolutionary algorithm is used. The optimization process is studied in three independent cases. Firstly, the optimization is done for a single profile of strut cover from hub to shroud. Secondly, two profiles are selected for the strut covers, one in the hub section and the other in the shroud section. Finally, the optimization process is done for the strut cover and DIFFUSER channel geometries simultaneously. In order to produce the strut cover profiles the PARSEC parameterization method is used. The turbulent 3D flow is solved using computational fluid dynamic (CFD). The optimization process starts with the initial sampling of solution domain and subsequently the genetic algorithm (GA) is used to find the global optimum. The swirling flow at the TURBINE exit with the Reynolds number of 1.7 ×105 based on the hydraulic diameter of the DIFFUSER inlet is optimized. All steps of GA and corresponding processes of model creation, mesh generation by TurboGrid, flow simulation by ANSYS CFX and goal function calculation for all members of each generation are coded in the MATLAB platform. As a result of the optimization, the pressure recovery coefficients increased 1.94%, 3.1% and 7.42% in the first, second and third cases of the optimization process respectively.

An analysis of the EXHAUST DIFFUSER section of a GAS TURBINE is presented by incorporating the reduced order mathematical model “ actuator disc concept” that represents the last stage of the TURBINE. The actuator disc model is one of the simplified numerical methods for analyzing the aerodynamic performance of axial TURBINE stage. In which, the rotor and the stator of the TURBINE stages are modeled as zero thickness discs with a specified blade speed and zero speed respectively. Finite volume based commercial CFD package ANSYS FLUENT was employed for the numerical investigation of the applicability of the proposed simplified model. The compressible Navier-Stoke equations along with k- turbulent model were solved in the computational domain by incorporating suitable boundary conditions. The implementation of actuator disc boundary conditions is described in detail. The numerical results obtained from the proposed model are in good agreement with the experimental data available in the literature. The effect of casing angle on the performance of DIFFUSER is presented.

Micro scale GAS TURBINEs are low cost, simplified versions of full scale jet engines. A unique feature of their design are centrifugal compressor impellers that are selected from automotive low cost, high quality turbocharger components. The present article is dedicated to the practical design of a micro scale centrifugal compressor DIFFUSER that suits a reduced scale, turbojet engine. The idea of using a simplified method comes from the requirement from fast geometry generation for a prototype design. The chosen approach is suitable when the time is crucial and available resources are limited. The chosen simplified analytical model is based on turbomachinery physics. The obtained results are verified by detailed data from successful designs such as KJ66, MW54 and TK50. For a prototype design, GT60 results where compared with a numeric simulation in the ANSYS CFX environment. The difference in isentropic efficiency, numerical prediction in comparison to compressor flow map was less than 3%. This is acceptable for preliminary calculations due to the difference in compressor stator design.

In this paper, the influences of regional pre-evacuation of an altitude test facility on starting time of a second throat supersonic EXHAUST DIFFUSER are numerically investigated. Detailed numerical studies have been carried out to evaluate the physics of the flow and starting time of the DIFFUSER for different pre-evacuation zones along the DIFFUSER and the test chamber. Unsteady axisymmetric compressible Navier–Stokes equations, incorporated with the two equation kw-SST turbulence model are solved, with density-based solver to extract the current flow features. The numerical method is properly validated with the measured data available in the literature. Our investigations show that the amount of pre-evacuation volume has strong effects on starting time of the DIFFUSER. As we extend pre-evacuation zone along the DIFFUSER, the smaller starting time of DIFFUSER is resulted. However, the increasing of pre-evacuated test chamber size causes the increasing of starting time of the DIFFUSER.

This paper is presented to investigate the deposition effect on a second throat EXHAUST DIFFUSER performance. In the numerical simulation, the blockage of the DIFFUSER due to the deposition of aluminum oxide is considered by a gradual and time-dependent cross-section constriction. In the initial conditions, the supersonic flow has been established in the nozzle and DIFFUSER. DIFFUSER cross-section area is reduced by using a dynamic mesh method during the solution. The flow is considered compressible, viscous, and 2 dimensional axis-symmetric. The k-ω shear stress transport turbulence model is used to solve the turbulent flow field. DIFFUSER blockage (n) is equal to the ratio of instantaneous and primary diameters of the second-throat. By changing the value of n from 1 to 0.75, the onset of flow separation is moved to the downstream location in the DIFFUSER. This results in a considerable reduction of total pressure loss and then improves the flow pressure recovery. Decreasing parameter n from 0.75 to 0.64, the flow structure is subjected to severe changes and the separation of the flow occurs near the DIFFUSER inlet or inside the nozzle. In this condition, the DIFFUSER state changes from starting to un-starting mode. Therefore, the vacuum condition vanishes in the test chamber.

In this paper, a recurrent fuzzy-neural network (RFNN) controller with neural network identifier in direct control model is designed to control the speed and EXHAUST temperature of the GAS TURBINE in a combined cycle power plant. Since the TURBINE operation in combined cycle unit is considered, speed and EXHAUST temperature of the GAS TURBINE should be simultaneously controlled by fuel command signal and inlet guide vane position. Also practical limitations are applied to system inputs. In addition, demand power and ambient temperature are considered as disturbance. Simulation results show the effectiveness of proposed controller in comparison with other conventional methods such as Model Predictive Control (MPC) and H∞ control in a same operating condition.

In this paper, a recurrent fuzzy-neural network (RFNN) controller with neural network identifier in direct control model is designed to control the speed and EXHAUST temperature of the GAS TURBINE in a combined cycle power plant. Since the TURBINE operation in combined cycle unit is considered, speed and EXHAUST temperature of the GAS TURBINE should be simultaneously controlled by fuel command signal and inlet guide vane position. Also practical limitations are applied to system inputs. In addition, demand power and ambient temperature are considered as disturbance. Simulation results show the effectiveness of proposed controller in comparison with other conventional methods such as Model Predictive Control (MPC) and H¥ control in a same operating condition.

A proper design of EXHAUST hood geometry is very much essential in order to improve the overall efficiency of the steam TURBINE plant. The geometry of the non-axisymmetric EXHAUST hood makes the fluid flow at the exit of the steam TURBINE to be radially and circumferentially non-uniform. This work involves computational simulation of steam TURBINE asymmetric EXHAUST hood flows by incorporating the actuator-disc concept. The ANSYS FLUENT, finite volume based CFD solver is used for the present computational study. In the present simulation, the implementation of actuator disc boundary conditions with and without tip leakage is described in detail. The Actuator disc model approach exhibits a similar steam TURBINE EXHAUST hood flow asymmetry and static pressure recovery compared with the results reported in the literature, highlighting the applicability of the present model in coupling the rotor tip leakage jet with the steam TURBINE hood flow structure with less computational effort.

With the gradual reduction of available fossil fuel reserves and environmental impacts, the rate of use of renewable energy in the world has increased. One of the advantages of finite fuels is the constant availability of their use, to achieve sustainability in the supply of energy carriers. Subsequently, to meet the demand in various sectors, it is necessary. Develop technologies to use new energy. One of these renewable energy sources is the offshore energy of the seas and oceans, which has significant potential in the Persian Gulf of Iran. There are many ways to achieve kinetic energy due to the Stream of fluid created by the gravitational pull of the moon on the open waters, such as the use of horizontal axis TURBINEs. Since these types of TURBINEs have the same technology as the horizontal wind TURBINE built in different parts of Iran, they can be a good option for the construction of a power plant in Iran. In this paper, the effect of current amplifier DIFFUSERs on the tidal TURBINE and its impact on increasing the received power by the numerical method has been investigated. To investigate the numerically the TURBINE Stream, the confusion model of the two SST equivalents is used in the Ansys CFX fluid dynamics software. The geometry of the DIFFUSER and TURBINE has been studied separately. And the proposed model includes a TURBINE with a channel, in which the increase in power is about four times that of the no channels mode.