Note on Matching a Supersonic Intake to an Aircraft Gas Turbine

1958 ◽  
Vol 62 (567) ◽  
pp. 219-220
Author(s):  
J. M. Stephenson
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Static Pressure ◽  
Stagnation Pressure ◽  
Local Flow ◽  
Air Mass ◽  
Supersonic Flight ◽  
Turbine Engine ◽  
Air Intake ◽  
Mach Numbers

The Function of the air intake of a gas turbine engine is to deliver whatever air mass flow is required, with the best recovery of ram stagnation pressure, over the desired range of flight speeds and altitudes.Although it is generally shown in other forms, the performance of an air intake for supersonic flight can be represented on charts very similar to those of a rotating compressor. In Fig. 1 the ratio between ambient (static) pressure and stagnation pressure at the diffuser of a typical intake is shown as a function of corrected inlet and outlet air mass flow (which are themselves functions of the local flow Mach numbers), for a series of flight Mach numbers.

Effect of Divergence Angle on Flow Through Inlet Section of Diffuser of a Gas Turbine Combustion Chamber: The CFD Approach

2006 ◽  
Author(s):  
Digvijay B. Kulshreshtha ◽  
S. A. Channiwala ◽  
Jitendra Chaudhary ◽  
Zoeb Lakdawala ◽  
Hitesh Solanki ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Total Pressure ◽  
Divergence Angle ◽  
Velocity Head ◽  
Turbine Engine ◽  
Inlet Velocity ◽  
Pressure Losses ◽  
Flow Through ◽  
Mach Numbers

In the combustor inlet diffuser section of gas turbine engine, high-velocity air from compressor flows into the diffuser, where a considerable portion of the inlet velocity head PT3 − PS3 is converted to static pressure (PS) before the airflow enters the combustor. Modern high through-flow turbine engine compressors are highly loaded and usually have high inlet Mach numbers. With high compressor exit Mach numbers, the velocity head at the compressor exit station may be as high as 10% of the total pressure. The function of the diffuser is to recover a large proportion of this energy. Otherwise, the resulting higher total pressure loss would result in a significantly higher level of engine specific fuel consumption. The diffuser performance must also be sensitive to inlet velocity profiles and geometrical variations of the combustor relative to the location of the pre-diffuser exit flow path. Low diffuser pressure losses with high Mach numbers are more rapidly achieved with increasing length. However, diffuser length must be short to minimize engine length and weight. A good diffuser design should have a well considered balance between the confliction requirements for low pressure losses and short engine lengths. The present paper describes the effect of divergence angle on diffuser performance for gas turbine combustion chamber using Computational Fluid Dynamic Approach. The flow through the diffuser is numerically solved for divergence angles ranging from 5 to 25°. The flow separation and formation of wake regions are studied.

Evaluation of Cathode Air Flow Transients in a SOFC/GT Hybrid System Using Hardware in the Loop Simulation

2014 ◽  
Author(s):  
Nana Zhou ◽  
Chen Yang ◽  
David Tucker
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Hybrid System ◽  
Mass Flow ◽  
Cell System ◽  
Department Of Energy ◽  
Dynamic Responses ◽  
Partial Recovery ◽  
Fuel Cell System ◽  
Air Mass

Thermal management in the fuel cell component of a direct fired solid oxide fuel cell gas turbine (SOFC/GT) hybrid power system, especially during an imposed load transient, can be improved by effective management and control of the cathode air mass flow. The response of gas turbine hardware system and the fuel cell stack to the cathode air mass flow transient was evaluated using a hardware-based simulation facility designed and built by the U.S. Department of Energy, National Energy Technology Laboratory (NETL). The disturbances of the cathode air mass flow were accomplished by diverting air around the fuel cell system through the manipulation of a hot-air bypass valve in open loop experiments. The dynamic responses of the SOFC/GT hybrid system were studied in this paper. The evaluation included distributed temperatures, current densities, heat generation and losses along the fuel cell over the course of the transient along with localized temperature gradients. The reduction of cathode air mass flow resulted in a sharp decrease and partial recovery of the thermal effluent from the fuel cell system in the first 10 seconds. In contrast, the turbine rotational speed did not exhibit a similar trend. The collection of distributed fuel cell and turbine trends obtained will be used in the development of controls to mitigate failure and extend life during operational transients.

scholarly journals Comparison of Coriolis and Turbine Type Flow Meters for Fuel Measurement in Gas Turbine Testing

1993 ◽  
Author(s):  
J. D. MacLeod ◽  
W. Grabe
Keyword(s):  
Steady State ◽  
Gas Turbine ◽  
Mass Flow ◽  
Gas Turbines ◽  
Gas Turbine Engine ◽  
Turbine Engine ◽  
Turbine Flowmeter ◽  
Turbine Performance ◽  
Coriolis Flowmeter ◽  
Project Objectives

The Machinery and Engine Technology (MET) Program of the National Research Council of Canada (NRCC) has established a program for the evaluation of sensors to measure gas turbine engine performance accurately. The precise measurement of fuel flow is an essential part of steady-state gas turbine performance assessment. Prompted by an international engine testing and information exchange program, and a mandate to improve all aspects of gas turbine performance evaluation, the MET Laboratory has critically examined two types of fuel flowmeters, Coriolis and turbine. The two flowmeter types are different in that the Coriolis flowmeter measures mass flow directly, while the turbine flowmeter measures volumetric flow, which must be converted to mass flow for conventional performance analysis. The direct measurement of mass flow, using a Coriolis flowmeter, has many advantages in field testing of gas turbines, because it reduces the risk of errors resulting from the conversion process. Turbine flowmeters, on the other hand, have been regarded as an industry standard because they are compact, rugged, reliable, and relatively inexpensive. This paper describes the project objectives, the experimental installation, and the results of the comparison of the Coriolis and turbine type flowmeters in steady-state performance testing. Discussed are variations between the two types of flowmeters due to fuel characteristics, fuel handling equipment, acoustic and vibration interference and installation effects. Also included in this paper are estimations of measurement uncertainties for both types of flowmeters. Results indicate that the agreement between Coriolis and turbine type flowmeters is good over the entire steady-state operating range of a typical gas turbine engine. In some cases the repeatability of the Coriolis flowmeter is better than the manufacturers specification. Even a significant variation in fuel density (10%), and viscosity (300%), did not appear to compromise the ability of the Coriolis flowmeter to match the performance of the turbine flowmeter.

scholarly journals Off-Design Performances of an Organic Rankine Cycle for Waste Heat Recovery from Gas Turbines

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1105 ◽  
Author(s):  
Carlo Carcasci ◽  
Lapo Cheli ◽  
Pietro Lubello ◽  
Lorenzo Winchler
Keyword(s):  
Gas Turbine ◽  
Mass Flow Rate ◽  
Air Temperature ◽  
Mass Flow ◽  
Flow Rate ◽  
Power Output ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Ambient Air ◽  
Air Mass

This paper presents an off-design analysis of a gas turbine Organic Rankine Cycle (ORC) combined cycle. Combustion turbine performances are significantly affected by fluctuations in ambient conditions, leading to relevant variations in the exhaust gases’ mass flow rate and temperature. The effects of the variation of ambient air temperature have been considered in the simulation of the topper cycle and of the condenser in the bottomer one. Analyses have been performed for different working fluids (toluene, benzene and cyclopentane) and control systems have been introduced on critical parameters, such as oil temperature and air mass flow rate at the condenser fan. Results have highlighted similar power outputs for cycles based on benzene and toluene, while differences as high as 34% have been found for cyclopentane. The power output trend with ambient temperature has been found to be influenced by slope discontinuities in gas turbine exhaust mass flow rate and temperature and by the upper limit imposed on the air mass flow rate at the condenser as well, suggesting the importance of a correct sizing of the component in the design phase. Overall, benzene-based cycle power output has been found to vary between 4518 kW and 3346 kW in the ambient air temperature range considered.

Effect of Moisture Content on Mixing Air With Water-Liquid Flowing Through Inverted U-Tube for Power Plant Condenser Applications

2019 ◽  
Author(s):  
Khaled Yousef ◽  
Ahmed Hegazy ◽  
Abraham Engeda
Keyword(s):  
Water Vapor ◽  
Mass Flow ◽  
Static Pressure ◽  
Air Entrainment ◽  
Vapor Mixture ◽  
Flow Rates ◽  
Air Mass ◽  
Side Tube ◽  
Mass Flow Rates ◽  
Vapor Mass

Abstract Computational Fluid Dynamics (CFD) for air/water-vapor and water-liquid two-phase flow mixing with condensation in a vertical inverted U-tube is presented in this paper. This study is to investigate the flow behaviors and underlying some physical mechanisms encountered in air/water-vapor and water-liquid mixing flow when condensation is considered. Water-liquid flows upward-downward through the inverted U-tube while the air/water-vapor mixture is extracted from a side-tube just after the flow oriented downward. The CFD simulation is carried out for a side air/water-vapor mixture volume fraction (αm) of 0.2–0.7, water-vapor mass fraction (Xv) of 0.1–0.5 in the side air/water-vapor mixture and water-liquid mass flowrate (mw) of 2,4,6, and 8 kg/s. The present results reveal that, at lower air mass flow rate, no significant effect of Xv on the generated static pressure at the inverted U-tube higher part. However, by increasing the air mass flow rates, ma ≥ 0.001 at mw = 2 kg/s, and ma ≥ 0.00125 at mw = 4 kg/s, we can infer that the lowest static pressure can be attained at Xv = 0.1. This may be attributed to the increased vapor and air mass flow rates from the side tube which results in shifting the condensation from the tube highest part due to air accumulation. This leads to increasing the flow pressure and decelerating the water-liquid flow. Raising mw from 2 to 4 kg/s at the same vapor mass ratio results in a lower static pressure due to more condensation of water vapor. The turbulent intensity and kinetic energy starts to drop approximately at ma = 0.002 kg/s, and αm = 0.55–0.76 at mw = 2 kg/s for all Xv values but no noticeable change at mw = 4 kg/s occurs. These findings estimate the operational values of air and water mass flow rates for stable air entrainment from the side-tube. Increasing the air and vapor mass ratio over these values may block the evacuation process and fails the system continuance. Likewise more air entrainment from the side-tube will decelerate the water flow through the inverted U-tube and hence the flow velocity will decrease thereafter. Moreover, this study reveals that the inverted U-tube is able to generate a vacuum pressure down to 55.104 kPa for the present model when vapor condensation is considered. This generated low-pressure helps to vent an engineering system from the non-condensable gases and water vapor that fail its function if these are accumulated with time. Moreover, the water-liquid mass flow rate in the inverted U-tube can be used to sustain the required operating pressure for this system and extract the non-condensable gases with a less energy consuming system. The present CFD model provides a good physical understanding of the flow behavior for air/water-vapor and water-liquid flow for possible future application in the steam power plant.

Investigation of Flow Instabilities Near the Rim Cavity of a 1.5 Stage Gas Turbine

2009 ◽  
Author(s):  
M. Rabs ◽  
F.-K. Benra ◽  
H. J. Dohmen ◽  
O. Schneider
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Gas Turbines ◽  
Flow Instabilities ◽  
Navier Stokes ◽  
Flow Rates ◽  
Air Mass ◽  
Hot Gas ◽  
Path Modelling ◽  
Mass Flow Rates

The present paper gives a contribution to a better understanding of the flow at the rim and in the wheel space of gas turbines. Steady state and time-accurate numerical simulations with a commercial Navier-Stokes solver for a 1.5 stage turbine similar to the model treated in the European Research Project ICAS-GT were conducted. In the framework of a numerical analysis, a validation with experimental results of the test rig at the Technical University of Aachen will be given. In preceding numerical investigations of realistic gas turbine rim cavities with a simplified treatment of the hot gas path (modelling of the main flow path without blades and vanes), so called Kelvin-Helmholtz vortices were found in the area of the gap when using appropriate boundary conditions. The present work shows that these flow instabilities also occur in a 1.5 stage gas turbine model with consideration of the blades and vanes. Therefore, several simulations with different sealing air mass flow rates (CW 7000, 20000, 30000) have been conducted. The results show, that for high sealing air mass flow rates Kelvin-Helmholtz Instabilities are developing. These vortices significantly coin the flow at the rim.

Application of Inlet Fogging for Power Augmentation of Mechanical Drive Turbines in the Oil and Gas Sector

2006 ◽  
Author(s):  
Abdalla M. Al-Amiri ◽  
Montaser M. Zamzam ◽  
Mustapha A. Chaker ◽  
Cyrus B. Meher-Homji
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Gas Turbines ◽  
Oil And Gas ◽  
Critical Parameters ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Air Mass ◽  
Power Turbine ◽  
Oil And Gas Sector

The use of inlet fogging systems to boost the power for gas turbine engines is well known and extensively applied in the power generation field. In this paper the application of inlet fogging of gas turbine engines utilized in the oil and gas sector for mechanical drive applications is covered. Extracting oil from a well is often limited by the rate of gas extraction, and consequently by the gas turbine power and efficiency. In hot and dry air climates, such as desert areas of the gulf countries, gas turbine engine power output is dramatically reduced because of the reduction in gas turbine air mass flow. This effect is even more predominant with aeroderivative units that are commonly used in this sector. Cooling the air to the wet bulb temperature, will increase the density of the air, increase the air mass flow, and boost the power and efficiency. Consequently the amount of extracted gas, and therefore oil, will be substantially increased. With such a cooling potential, and the current trend in oil prices, inlet fogging can have a very rapid payback. In this paper, the behavior of gas turbines with and without fog injection will be analyzed in detail based on actual field data. Critical parameters such as the power turbine inlet temperature, exhaust temperatures, compressor discharge pressure, the gas generator and power turbine speeds, as increasing stages of fogging are applied are covered. Furthermore, specific issues relating to the design and control of fogging as applied to aeroderivative engines will be discussed.

Refrigerating Gas Turbine Compressor Air Intake

1981 ◽  
Author(s):  
R. M. Sadek
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Compression Ratio ◽  
Gas Turbines ◽  
Air Mass ◽  
Ambient Temperatures ◽  
Air Intake ◽  
Gas Turbine Compressor ◽  
System Power ◽  
Surplus Power

Gas turbines power output is adversely influenced by increasing ambient temperatures. This is mainly caused by the reduction both in the air mass flow rate through the compressor and the developed compression ratio. It is claimed that refrigerating the compressor air intake down to 0 C, will generate enough power to cope with refrigerating system power requirements as well as leaving ample surplus power.

Accurate Field Compressor Inlet Flow Measurement System

2019 ◽  
Author(s):  
Joshua McConkey ◽  
Richard H. Bunce ◽  
Heiko Claussen
Keyword(s):  
Pressure Drop ◽  
Gas Turbine ◽  
Mass Flow ◽  
Measurement System ◽  
Flow Measurement ◽  
Engine Performance ◽  
Flow Meters ◽  
Air Mass ◽  
Safety Margins ◽  
Compressor Inlet

Abstract Understanding the amount of air that enters a gas turbine is important for calculating their performance and efficiency. Flow meters are almost never used to measure that flow in production engines. Typical flow meters are impractical because the air flow into the compressor is very large, up to 1400 lbs/s (635 kg/s) or 1,000,000 ft3/min (28,300 m3/min), and typically an intentional pressure drop is involved in the measurement. This pressure drop negatively impacts the performance of the engine. If inlet air mass flow were known accurately without negatively impacting the engine performance, then engines could be run more efficiently. Currently, inlet mass flow is typically inferred, rather than measured. This leads to increased safety margins which require engines to be run more conservatively, i.e., at lower power. This paper describes a novel, inexpensive, and accurate air mass flow measurement system with negligible impact on engine performance.

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