Account of Film Turbulence for Predicting Film Cooling Effectiveness in Gas Turbine Combustors

The paper deals with a small but important part of the overall gas turbine engine combustion system and continues earlier published work on turbulence effects in film cooling to cover the case of film turbulence. Film cooling of the gas turbine combustor liner imposes certain geometric limitations on the coolant injection device. The impact of practical film injection geometry on the cooling is one of increased rates of film decay when compared to the performance from idealized injection geometries at similar injection conditions. It is important to combustor durability and life estimation to be able to predict accurately the performance obtainable from a given practical slot. The coolant film is modeled as three distinct regions, and the effects of injection slot geometry on the development of each region are described in terms of film turbulence intensity and initial circumferential non-uniformity of the injected coolant. The concept of the well-designed slot is introduced and film effectiveness is shown to be dependent on it. Only slots which can be described as well-designed are of interest in practical equipment design. A prediction procedure is provided for well-designed slots which describes growth of the film downstream of the first of the three film regions. Comparisons of predictions with measured data are made for several very different well-designed slots over a relatively wide range of injection conditions, and good agreement is shown.

Wind Tunnel Model Study of the Hot Exhaust Plume From the Compressor Research Facility at Wright-Patterson Air Force Base, OH

This paper presents the results of a wind tunnel model study to determine temperatures at various locations generated by the hot exhaust air from the Compressor Research Facility [CRF] which is being built at Wright-Patterson Air Force Base, Ohio. The study was designed to provide data at the inlet to the CRF and at other nearby locations where pedestrians, building ventilation systems, and vegetation might be affected. The test program, which was conducted in the Calspan Atmospheric Simulation Facility, included flow visualization studies and quantitative concentration measurements of a tracer gas from which full-scale temperature could be calculated. The concentration measurements were performed for a number of wind speeds at each of twelve different wind directions. Two exhaust flows and two exhaust stack configurations were studied.

Alternate Fuels and the Gas Turbine Catalytic Combustor

Inasmuch as conventional gas turbine combustors often produce soot even with the present low aromatic content fuels, the production of acceptable liquid turbine fuels from hydrogen deficient raw materials such as coal and tar sands requires large quantities of high cost hydrogen if conventional combustors are to be used. The economics of producing alternate turbine fuels would be improved if high aromatic content fuels could be burned in gas turbines without soot formation. Gas turbines using the catalytic combustor not only can efficiently burn highly aromatic fuels without soot formation but can meet all existing or proposed regulations on emissions of hydrocarbons, carbon monoxide, and nitrogen oxides. Under certain conditions, high fuels can be burned with as little as 10 to 15 percent conversion of the fuel nitrogen to nitrogen oxides. In view of the potential savings, any program for alternate fuels should take into account the opportunities offered by the catalytic combustor.

Radiative Heat Transfer From Gas Turbine Flames

Measurements have been made of the normal component of the radiative heat flux to the wall of a model gas turbine combustor with and without a mirrored background. Measurements have also been made of the centerline soot concentration. The data show that the heat flux correlated with the soot concentration but not universally, since JET A fuel yielded a different curve 1han DIESEL fuel. A theoretical analysis of the heat flux from a soot suspension was formulated. A criterion was established for the use of a small particle analysis. Finally, it is shown that there is no correspondence between theory and these experiments. It is speculated that turbulent fluctuations need to be modeled.

Closed Cycle Gas Turbines: An ECAS Update — Part 1

This paper presents a discussion of the significant results of a study program conducted for the Department of Energy to evaluate the potential for closed cycle gas turbines and the associated combustion heater systems for use in coal fired public utility power plants. Two specific problem areas were addressed: (a) the identification and analysis of system concepts which offer high overall plant efficiency consistent with low cost of electricity (COE) from coal-pile-to-bus-bar, and (b) the identification and conceptual design of combustor/heat exchanger concepts compatible for use as the cycle gas primary heater for those plant systems. The study guidelines were based directly upon the ground rules established for the ECAS studies to facilitate comparison of study results. Included is a discussion of a unique computer model approach to accomplish the system analysis and parametric studies performed to evaluate entire closed cycle gas turbine utility power plants with and without Rankine bottoming cycles. Both atmospheric fluidized bed and radiant/convective combustor /heat exchanger systems were addressed. Each incorporated metallic or ceramic heat exchanger technology. The work culminated in conceptual designs of complete coal fired, closed cycle gas turbine power plants. Critical component technology assessment and cost and performance estimates for the plants are also discussed.

Thermal Influences in Gas Turbine Transients: Effects of Changes in Compressor Characteristics

During transients of axial-flow gas turbines, the characteristics of the compressor are altered. The changes in these characteristics (excluding surge line changes) have been related to transient heat transfer parameters, and these relations have been incorporated in a program for predicting the transient response of a single-shaft aero gas turbine. The effect of the change in compressor characteristics has been examined in accelerations using two alternative acceleration fuel schedules. When the fuel is scheduled on compressor delivery pressure alone. there is no increase in predicted acceleration times. When the fuel is scheduled on shaft speed alone, the predicted acceleration times are increased by about 5 to 6 percent.

Fuel Effects in Recent Combustion Turbine Burner Tests of Six Coal Liquids

Comparative tests have been made in combustion turbine burners between six coal derived liquid (CDL) fuels and No. 2 distillate oil. All CDL fuels were evaluated in a half-scale (by diameter) combustor test rig, while one CDL fuel was also evaluated in a full scale high pressure combustion rig. The effects of these fuels on emissions of smoke and oxides of nitrogen, and on combustor metal temperature are discussed. Also observed in the testing were flame radiation, post-test combustor cleanliness, and emissions of carbon monoxide and hydrocarbons. Two of the CDLs do appear to be within the tolerance band which present combustion turbines can accept, with the exception of elevated NOx emissions. This work is part of an Electric Power Research Institute program to develop burners for coal derived liquids.

The Base Pressure Problem in Transonic Turbine Cascades

Base pressure data were systematically collected at VKI during recent years on a great variety of cascades operated over a wide range of outlet March numbers. An attempt is made to correlate these data by relating the base pressure to important cascade and flow parameters. Details about the trailing edge flow are obtained by using an enlarged model simulating the overhang section of convergent turbine cascades. The experimental cascade and model test results are compared with theoretical calculations using base pressure calculation methods.

A 2500 HP Addition to the Ruston Range

This paper describes the newly introduced Ruston TA2500 gas turbine. The design is based on that of the well proven TA1750 and retains its outstanding features of reliability, long life, and ease of maintenance. Component efficiencies have been improved to increase the overall thermal performance and the Ruston designed solid-state control system with its Rustronic solid-state governor has been incorporated to give greater operating flexibility. Other changes include a compressor driven auxiliary gearbox which obviates the necessity for motor driven auxiliary pumps and a new design of frame similar to that of the Ruston TB5000 gas turbine.

Electrocoalescer Comparison Performance Tests

Validation tests were carried out based upon tests specified in Military Specification MIL-F-8901. The Electrocoalescer has demonstrated excellent performance, has passed the validation test, and showed an improved performance over that of the Military Standard Filter Separator. When tested with diesel fuel, the improvement was on the order of a factor of 10 or more. Moreover, it demonstrated a lower overall pressure drop. Use of the Electrocoalescer in fuels decontamination service is expected to result in cleaner fuels and longer filter life.