Experimental Determination of Stator Endwall Heat Transfer

Local Stanton numbers were experimentally determined for the endwall surface of a turbine vane passage. A six vane linear cascade having vanes with an axial chord of 13.81 cm was used. Results were obtained for Reynolds numbers based on inlet velocity and axial chord between 73,000 and 495,000. The test section was connected to a low pressure exhaust system. Ambient air was drawn into the test section, inlet velocity was controlled up to a maximum of 59.4 m/sec. The effect of the inlet boundary layer thickness on the endwall heat transfer was determined for a range of test section flow rates. The liquid crystal measurement technique was used to measure heat transfer. Endwall heat transfer was determined by applying electrical power to a foil heater attached to the cascade endwall. The temperature at which the liquid crystal exhibited a specific color was known from a calibration test. Lines showing this specific color were isotherms, and because of uniform heat generation they were also lines of nearly constant heat transfer. Endwall static pressures were measured, along with surveys of total pressure and flow angles at the inlet and exit of the cascade.

Heat Transfer Measurements for Rotating Turbine Discs

To optimise the turbine disc weight and coolant flow requirements, the aspect of improving thermal analysis was investigated. As a consequence, an experimental investigation was undertaken to measure the rates of convective heat transfer. The constant temperature steady state technique was used to determine the local and average heat transfer coefficients on the sides of rotating discs. The effects of coolant flow rates, CW (3000 ≤ CW ≤ 18600) with two types of cavity in-flow conditions and of the rotational speeds, Reθ (from 4×105 to 1.86×106) on the disc heat transfer were studied and correlations developed. For a rotating disc in confined cavities with superimposed coolant flows, Nusselt numbers were found to be higher than those for the free rotating disc without confinement.

MS7001F Prototype Test Results

The MS7001F heavy–duty gas turbine has been designed utilizing advanced analytical methods and a substantial array of component tests. The integrity of the system required that the prototype unit, with its accessories, be rigorously tested under load. The factory load test was completed on May 18, 1988 after 387 hours and 134 start/stop cycles. The MS7001F prototype gas turbine was instrumented with more than 3000 pieces of instrumentation in order to record all critical temperatures, pressures, flows, strains, displacements, and other pertinent data. The load device was a modified MS7001E compressor, which also supplied the means by which the MS7001F prototype compressor’s pressure ratio was increased to provide for surge margin determination. Inlet throttling of the MS7001F compressor allowed for full firing temperature operation, at reduced load. The results of this factory prototype load test are reported in the paper as are observations made during post test teardown.

A Theory for Wake-Induced Transition

A theory for transition from laminar to turbulent flow as the result of unsteady, periodic passing of turbulent wakes in the free stream is developed using Emmons’ transition model. Comparisons made to flat plate boundary layer measurements and airfoil heat transfer measurements confirm the theory.

Development of a Low-NOx LBG Combustor for Coal Gasification Combined Cycle Power Generation Systems

From the view point of future coal utilization technology for the thermal power generation systems, the coal gasification combined cycle system has drawn special interest recently. In the coal gasification combined cycle power generation system, it is necessary to develop a high temperature gas turbine combustor using a low-BTU gas (LBG) which has high thermal efficiency and low emissions. In Japan a development program of the coal gasification combined cycle power generation system has started in 1985 by the national government and Japanese electric companies. In this program, 1300°C class gas turbines will be developed. If the fuel gas cleaning system is a hot type, the coal gaseous fuel to be supplied to gas turbines will contain ammonia. Ammonia will be converted to nitric oxides in the combustion process in gas turbines. Therefore, low fuel-NOx combustion technology will be one of the most important research subjects. This paper describes low fuel-NOx combustion technology for 1300°C class gas turbine combustors using coal gaseous low-BTU fuel as well as combustion characteristics and carbon monoxide emission characteristics. Combustion tests were conducted using a full-scale combustor used for the 150 MW gas turbine at the atmospheric pressure. Furthermore, high pressure combustion tests were conducted using a half-scale combustor used for the 1 50 MW gas turbine.

Transient Liquid Crystal Measurement of Local Heat Transfer on a Rotating Disk With Jet Impingement

All experimental technique has been developed for measurement of local convection heat transfer characteristics on rotating surfaces, utilizing thin liquid crystal surface coatings in a thermal transient test procedure. The encapsulated liquid crystal coatings used are sprayed directly on the test surface and their response is observed and processed during the transient with automated computer vision and data acquisition systems. Heat transfer coefficients are calculated from the thermal transient response of the test surface, as determined from the color indication from the thin coating. A significant advantage of the method, especially for convection in disk/shroud cavities that may contain recirculating fluid regions, is that appropriate thermal boundary conditions are naturally imposed on all of the boundary surfaces. The method is also relatively fast and inexpensive, and allows the geometry of the disk and stator surfaces to be changed easily, without the expenses of mounting discrete heat flux and temperature sensors and equipment to transfer information to a stationary frame of reference. Application of the experimental technique is demonstrated with detailed radially local surface Nusselt number distributions acquired for cases involving jet impingement onto a plane smooth disk, rotating in close proximity to a parallel plane stator disk. A single circular jet, with nozzle exit flush mounted in the stator, is oriented normal to the disk surface at various radii and flowrates. Local Nusselt numbers are presented nondimensionally as functions of both disk and flow Reynolds numbers. The results indicate that the local radial heat transfer distribution can be controlled by varying the impingement radius, but maximum radially averaged heat transfer is obtained with impingement at the disk center.

User Experience: Operating a 300 MW Base Load Cogeneration Plant With High Water Injection Rates to Control NOx Emissions

This paper describes user experience with the operation and maintenance of a gas turbine based cogeneration plant operating at base load while injecting up to 80 gpm (303 l/min) of water to control NOx emissions to 42 ppmv (at 15% O2). The plant, located in the Kern River Oil Field, near Bakersfield, California, has produced an average of 294.6 MWe and 1.903 million lbs/hr (0.863 million kg/hr) of steam since achieving commercial operation in August, 1985. To date, the plant has achieved an operational reliability and availability of 98.9% and 95.4%, respectively. The effects of water injection on combustion hardware, as well as, overall gas turbine reliability and availability and equipment enhancements will be discussed.

Gas Turbine Exhaust Expansion Joints, Diverter and Damper Designs for the New Generation of Higher Temperature, High Efficiency Gas Turbines

The purpose of this paper is to update the industry on the evolutionary steps that have been taken to address higher requirements imposed on the new generation combined cycle gas turbine exhaust ducting expansion joints, diverter and damper systems. Since the more challenging applications are in the larger systems, we shall concentrate on sizes from nine (9) square meters up to forty (40) square meters in ducting cross sections. (Reference: General Electric Frame 5 through Frame 9 sizes.) Severe problems encountered in gas turbine applications for the subject equipment are mostly traceable to stress buckling caused by differential expansion of components, improper insulation, unsuitable or incompatible mechanical design of features, components or materials, or poor workmanship. Conventional power plant expansion joints or dampers are designed for entirely different operating conditions and should not be applied in gas turbine applications. The sharp transients during gas turbine start-up as well as the very high temperature and high mass-flow operation conditions require specific designs for gas turbine application.

The Effects of Steam Injection in Combustion Air on the Thermal Efficiency and the Specific Work Output of a Stationary Gas Turbine Plant

In the present study a stationary open cycle gas turbine plant, including a thermal regenerator has been theoretically analyzed to assess the impact of steam addition in combustion air, on its performance. the effect of varying steam upto 15% air at different pressure ratios and turbine inlet temperatures have been reported. Mixing of steam in air results in higher values of cycle efficiency and increased specific work output, feasibility to generate steam needed for the purpose in a waste heat boiler have also been studied.

Impingement/Effusion Cooling: The Influence of the Number of Impingement Holes and Pressure Loss on the Heat Transfer Coefficient

Measurements of the overall heat transfer coefficient within an impingement/effusion cooled wall are presented. The FLUENT CFD computer code has been applied to the internal aerodynamics to demonstrate the importance of the internal recirculation in the impingement gap. This generates a convective heat transfer to the impingement jet and measurements of this heat transfer plate coefficient are presented that show it to be approximately a half of the impingement/effusion heat transfer coefficient. The influence of the relative pressure loss or X/D between the impingement and effusion was investigated, for an effusion X/D of 4.67 and a Z of 8 mm, and shown to be only significant at high G where a reduction in h of 20% occurred. Increasing the number of holes, N, in the impingement/effusion array at a constant Z of 8 mm reduced h by 20%, mainly due to the higher Z/D for the smaller holes at high N. Reduced numbers of impingement holes relative to the effusion holes, in a ratio of 1 to 4, were shown to have a small influence on h with a maximum reduction in h of 20% at high G and a negligible effect at low G.