Heat Transfer From a Rotating Disc

The local heat transfer from a plane rotating disc enclosed in a casing has been studied experimentally. The disc of 800 mm diameter can be run up to 2000 min−1 at axial distances between disc and casing varied between 5 and 55 mm. Centrifugal or alternatively centripetal flow of cooling air at rates up to ṁ = 1 kg/s can be applied, both with or without an inlet swirl. With the disc rotating in a closed casing (ṁ = 0 kg/s) the influence of the characteristic dimensionless groups on the local heat transfer has been investigated. At a fixed radius, a variation of the local Reynolds Number by either speed or density results in corresponding changes of the heat transfer. However, with a variation of the radius different heat transfer-Re relations are found. In fact, the temperature distribution in the gas caused by the heat flux results in an additional influence of free convection, to be expressed by a Grashof Number. This is confirmed by a comparison of the experimental results with calculations based on Reynolds Analogy and measured friction coefficients. The discrepancies found can be explained only, if in addition to the limitations of the analogy, the influence of free convection is taken into account. Additional results of ongoing experiments concerning the influence of the geometry of the cavity between disc and casing, of the coolant flow rate and of the swirl are presented.

Prediction and Measurement of Film Cooling Effectiveness for a First-Stage Turbine Vane Shroud

After compressor discharge air has initially been used to cool the heat shields of the hot gas inlet casing, it can subsequently be employed for film cooling of the first-stage vane shrouds. Since the flow field near these shrouds is three-dimensional, the film cooling effectiveness cannot be predicted correctly by common two-dimensional codes. The secondary flow transports the film from the pressure side to the suction side where it can even climb up the airfoil to cool its trailing section. Such film cooling effectiveness was first investigated experimentally in a linear vane cascade at atmospheric pressure. The temperatures and static pressure levels at the adiabatic shrouds, as well as the temperature measurements within the vane cascade, are reported for different cooling film blowing rates. In addition, the secondary flow was analysed numerically using a partially-parabolic computer code for 3D viscous flows. It involves mutual interaction of the boundary layer with the mainstream. The secondary flow can also be modelled with this algorithm, which requires less numerical effort than solving the fully 3D elliptic flow equations. The numerical results of the experiment and numerical predictions are compared. In addition, the application of these results to a high-temperature gas turbine is presented.

Future of Combined-Cycle Plants in Belgium

In this paper we investigate the possible penetration of combined-cycle plants in the Belgian electricity generation system after the Belgian Government has not considered as appropriate the construction of a next nuclear plant at the present time. First the characteristic features of the Belgian production capabilities are given. The share of gas turbines, turbojets and already existing combined-cycle plants and their operation modes are emphasized. Then, alternative options to nuclear energy are presented, i.e. repowering of existing plants and construction of new combined-cycle plants. The potentialities of gas turbines and CC plants as well as their future in Belgium are investigated. Finally we discuss the equipment plan for the Belgian generation system proposed by the management committee of the electrical plant operators. From the results of our research about repowering, gas turbines and new CC plants, we derive recommendations for the future production means in Belgium.

Combined Cycles Permit the Most Environmentally Benign Conversion of Fossil Fuels to Electricity

The environmental impact of unfired combined-cycle blocks of the GUD® type is compared with that of equivalent reheat steam boiler/turbine units. The outstandingly high efficiency of GUD blocks not only conserves primary-energy resources, but also commensurately reduces undesirable emissions and unavoidable heat rejection to the surroundings. In addition to conventional gas or oil-fired GUD blocks, integrated coal-gasification combined-cycle (ICG-GUD) blocks are investigated from an ecological point of view so as to cover the whole range of available fossil fuels. For each fuel and corresponding type of GUD power plant the most appropriate conventional steam-generating unit of most modern design is selected for comparison purposes. In each case the relative environmental impact is stated in the form of quantified emissions, effluents and waste heat, as well as of useful byproducts and disposable solid wastes. GUD blocks possess the advantage that they allow primary measures to be taken to minimize the production of NOx and SOx, whereas both have to be removed from the flue gases of conventional steam stations by less effective and desirable, albeit more expensive secondary techniques, e.g. flue-gas desulfurization and DENOX systems. In particular, the comparison of CO2 release reveals a significantly lower contribution by GUD blocks to the greenhouse effect than by other fossil-fired power plants.

Recent Progress in Research Pertaining to Estimates of Gas-Side Heat Transfer in an Aircraft Gas Turbine

A decade ago several important fundamental heat transfer phenomena were identified which were considered basic to the ability to predict heat transfer loads in aircraft gas turbines. The progress in addressing these fundamentals over the past ten years is assessed in this paper. Much research effort has been devoted to their study in university, industry and government laboratories and significant progress has been achieved. Advances in computer technology have enabled the modeling of complex three-D fluid flow in gas turbines so necessary for heat transfer calculations. Advances in instrumentation plus improved data acquisition have brought about more reliable data sets. While much has advanced in the ‘80’s, much challenging research remains to be done. Several of these areas are suggested in the paper.

MS 9001F: A New Advanced Technology 50 Hz Gas Turbine

Following a thorough market analysis, the MS 9001F heavy duty gas turbine has been designed using aerodynamic scaling based on the 60 Hz MS 7001F. Effort put into the design has been shared by the engineering departments of ALSTHOM and GE. This paper discusses the market surveys for large heavy duty gas turbines as well as the basis of design for the MS 9001F, which has been derived from the MS 7001F. Specifically discussed are the role of scaling, the design characteristics of the MS 7001F and the MS 9001F, the results of 7001F prototype testing, the test plan for the MS 9001F, plant lay out possibilities and ratings. The MS 9001F gas turbine uses advanced aircraft engine technology in its design, with a rating based on a firing temperature of 1260°C (2300°F), which is 156°C (280°F) higher and with compressor inlet flow 50% greater than its predecessor, the MS 9001E.

Large ‘Single Blade’ Diverters and Beyond

‘Single-Blade’ Diverters are now a standard component of gas turbine combined cycle and co-generation plants. The paper explains the key features which have to be considered in selecting a Diverter, such as the sealing system, flap assembly construction, drive components and actuation systems. Further the latest hydraulic operating systems are described. With these it is now possible to use Diverters to finely regulate the heat input to the recovery system as well as to switch over rapidly to simple cycle operation or auxiliary firing. Finally the paper shows how it is possible with a two module Diverter to avoid using separate Isolators (dampers) even for the largest gas turbines currently available.

The Effect of a Turbulent Wake on the Stagnation Point: Part I — Skin Friction Results

The response of a boundary layer in the stagnation region of a two-dimensional body to fluctuations in the freestream is examined. The analysis is restricted to laminar incompressible flow. The assumed form of the velocity distribution at the edge of the boundary layer represents both a pulsation of the incoming flow, and an oscillation of the stagnation point streamline. Both features are essential in accurately representing the effect which freestream spatial and temporal nonuniformities have upon the unsteady boundary layer. Finally, a simple model is proposed which relates the characteristic parameters in a turbulent wake to the unsteady boundary-layer edge velocity. Numerical results are presented for both an arbitrary two-dimensional geometry and a circular cylinder.

Assessing Diagnostic Techniques for Poblem Identification in Advanced Industrial Gas Turbines

This paper describes existing, developing, and needed methods for detection, identification, and diagnosis of problems in combustion turbines. The use of combustion turbines for electrical power generation is growing, and advanced models of large industrial turbines are now starting to enter service. In view of the harsh operating conditions and severe service to which these new turbines will be exposed, this paper evaluates sensors and signal analysis methods to detect and diagnose the problems which may surface in operation. Generic problems which have been observed in combustion turbine installations in the recent past are identified, and methods for detecting these problems, quantifying them, and isolating their causes are analyzed.

Heat Transfer Measurements and Calculations in Transitionally Rough Flow

Experimental data on a rough surface for both transitionally rough and fully rough turbulent flow regimes are presented for Stanton number distribution, skin friction coefficient distribution and turbulence intensity profiles. The rough surface is composed of 1.27 mm diameter hemispheres spaced in a staggered array four base diameters apart on an otherwise smooth wall. Special emphasis is placed on the characteristics of heat transfer in the transitionally rough flows. Stanton number data are reported for zero pressure gradient incompressible turbulent boundary layer air flow for nominal freestream velocities of 6, 12, 28, 43, 58 and 67 m/s, which give x-Reynolds numbers up to 10,000,000. These data are compared with previously published rough surface data, and the classification of a boundary layer flow into transitionally rough and fully rough regimes is explored. Moreover, a new heat transfer model for use in the previously published discrete element prediction approach is presented. Computations using the discrete element model are presented and compared with data obtained from two different rough surfaces. The discrete element predictions for both surfaces are found to be in substantial agreement with the data.