An Air-Cooled Jacket Designed to Protect Unsteady Pressure Transducers at Elevated Temperatures in Gas Turbine Engines

2002 ◽  
Author(s):  
Paul C. Ivey ◽  
Derek G. Ferguson
Keyword(s):  
Gas Turbine ◽  
Pressure Transducer ◽  
Elevated Temperatures ◽  
Thermal Protection ◽  
Pressure Sensors ◽  
Air Cooling ◽  
Pressure Transducers ◽  
Unsteady Pressure ◽  
Cooling Media ◽  
Aero Engines

Current unsteady pressure sensors have a limiting upper temperature range and with few exceptions cannot survive at the temperatures experienced in gas turbine aero-engines. This paper describes a design and development study of an air-cooled commercially available unsteady pressure transducer capable of operation at temperatures exceeding 900 °C. The research objective for this work is the following: To design a cooling adapter, using air as the cooling media, capable of protecting a standard unsteady pressure transducer, whose maximum operating temperature is around 250 °C. in a gas turbine engine environment where temperatures typically reach 800–l500 °C. In addition the provision of thermal protection must not adversely effect the measurement of unsteady pressure and the cooling adapter and transducer assembly must be small enough to access critical parts of the engine. Current transducer can operate at temperatures exceeding 250 °C; the purpose of this paper is to demonstrate the additional protection offered by air-cooling. The paper describes the validation experiments conducted for this design, the level of thermal protection achieved and the frequency response of the transducer/cooling jacket assembly.

scholarly journals Unsteady Pressure Measurement in a High Temperature Environment Using Water Cooled Fast Response Pressure Transducers

1995 ◽  
Author(s):  
D. G. Ferguson ◽  
P. C. Ivey
Keyword(s):  
High Temperature ◽  
Elevated Temperatures ◽  
Thermal Protection ◽  
Dynamic Pressure ◽  
Fast Response ◽  
Ambient Conditions ◽  
Pressure Transducers ◽  
Unsteady Pressure ◽  
Temperature Environment ◽  
High Temperature Environment

Measurement of unsteady pressure is a requirement in many proposed aero-engine active control systems. In the high temperature environment associated with the engine, thermally unprotected transducers may not measure accurately or even survive. This paper reports an examination of two water cooled, commercially available unsteady pressure transducers, which assesses the ability of the transducer to accurately measure unsteady pressure when mounted in a water cooling adapter and the effectiveness of the thermal protection at high temperatures. Mounting the transducer in a cooling adapter was shown to have no adverse effect upon its ability to measure dynamic pressure. Deliberately recessing the adapter back from the flow provided the most stable and predictable output at all flow conditions tested. Thermal protection allowed the transducer to survive at flow temperatures of up to 500°C with a potential to survive at higher temperatures. No reduction in performance is shown at elevated temperatures relative to performance at ambient conditions.

A High-Temperature Assessment of Air-Cooled Unsteady Pressure Transducers

1998 ◽  
Vol 120 (3) ◽  
pp. 608-612 ◽  
Author(s):  
D. G. Ferguson ◽  
P. C. Ivey
Keyword(s):  
High Temperature ◽  
Control Systems ◽  
Thermal Protection ◽  
Transfer Model ◽  
Test Bed ◽  
Cooling Effectiveness ◽  
Pressure Transducers ◽  
Unsteady Pressure ◽  
Cooling Medium ◽  
Source Flow

This paper discusses the problem of measuring unsteady pressure in a high-temperature environment using standard transducers. Commercially available cooling adapters for these transducers use water as the cooling medium to provide thermal protection. This arrangement is suitable only for some test bed applications and not suitable for integration into in-flight active control systems. An assessment of the cooling effectiveness of a commercial water-cooled adapter using air as the cooling medium is presented using an experimentally validated finite element heat transfer model. The assessment indicates survival of an air-cooled transducer, itself rated to 235°C, at source flow temperatures up to 800°C.

On Thermodynamics of Gas-Turbine Cycles: Part 3—Thermodynamic Potential and Limitations of Cooled Reheat-Gas-Turbine Combined Cycles

1986 ◽  
Vol 108 (1) ◽  
pp. 160-168 ◽  
Author(s):  
M. A. El-Masri
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Closed Loop ◽  
Elevated Temperatures ◽  
Pressure Ratio ◽  
Air Cooling ◽  
Full Potential ◽  
Evaporative Water ◽  
Combined Cycles ◽  
Cooling Technology

Reheat gas turbines have fundamental thermodynamic advantages in combined cycles. However, a larger proportion of the turbine expansion path is exposed to elevated temperatures, leading to increased cooling losses. Identifying cooling technologies which minimize those losses is crucial to realizing the full potential of reheat cycles. The strong role played by cooling losses in reheat cycles necessitates their inclusion in cycle optimization. To this end, the models for the thermodynamics of combined cycles and cooled turbines presented in Parts 1 and 2 of this paper have been extended where needed and applied to the analysis of a wide variety of cycles. The cooling methods considered range from established air-cooling technology to methods under current research and development such as air-transpiration, open-loop, and closed-loop water cooling. Two schemes thought worthy of longer-term consideration are also assessed. These are two-phase transpiration cooling and the regenerative thermosyphon. A variety of configurations are examined, ranging from Brayton-cycles to one or two-turbine reheats, with or without compressor intercooling. Both surface intercoolers and evaporative water-spray types are considered. The most attractive cycle configurations as well as the optimum pressure ratio and peak temperature are found to vary significantly with types of cooling technology. Based upon the results of the model, it appears that internal closed-loop liquid cooling offers the greatest potential for midterm development. Hybrid systems with internally liquid-cooled nozzles and traditional air-cooled rotors seem most attractive for the near term. These could be further improved by using steam rather than air for cooling the rotor.

Correcting for Response Lag in Unsteady Pressure Measurements in Water

1993 ◽  
Vol 115 (4) ◽  
pp. 676-679 ◽  
Author(s):  
Rand N. Conger ◽  
B. R. Ramaprian
Keyword(s):  
Dynamic Response ◽  
Pressure Transducer ◽  
Water Channel ◽  
Inadequate Response ◽  
Pressure Measurements ◽  
Pressure Transducers ◽  
Pitching Airfoil ◽  
Unsteady Pressure ◽  
Unsteady Pressure Measurements ◽  
Type Pressure

There is not much information available on the use of diaphragm-type pressure transducers for the measurement of unsteady pressures in liquids. A procedure for measuring the dynamic response of a pressure transducer in such applications and correcting for its inadequate response is discussed in this report. An example of the successful use of this method to determine unsteady surface pressures on a pitching airfoil in a water channel is presented.

Harsh Environment Pressure Transducers Employing Metal Diaphragms and Silicon on Insulator Sensing Networks for Gas Turbine Application

2008 ◽  
Author(s):  
Anthony D. Kurtz ◽  
Boaz Kochman ◽  
Alex A. Ned
Keyword(s):  
Gas Turbine ◽  
Elevated Temperatures ◽  
Dynamic Pressure ◽  
Dynamic Performance ◽  
Extreme Environments ◽  
Silicon On Insulator ◽  
Turbine Engines ◽  
Pressure Transducers ◽  
Piezoresistive Sensor ◽  
Metal Diaphragm

It has long been necessary in many applications to measure pressure in extremely harsh environments at elevated temperatures. Examples of such applications include: gas turbine engines (both ground-based and for aircraft), automotive combustion, and down-hole applications for gas and oil industry. This paper reports on the latest developments of metal diaphragm transducers with Silicon-On-Insulator (SOI) piezoresistive sensor networks for ultra extreme environments. The design of the latest Inconel-diaphragm miniature, dynamic pressure transducers capable of operating reliably under extreme environmental conditions (temperatures up to 500°C and accelerations greater than 200g) — is described in detail. The performance of such metal diaphragm pressure transducers is presented and indicates that ruggedized, piezoresistive transducers with excellent static and dynamic performance characteristics are capable of operation in extremely harsh, high temperature gas turbine environments.

scholarly journals Experimental and Numerical Study of the Time-Dependent Pressure Response of a Shock Wave Oscillating in a Nozzle

1993 ◽  
Author(s):  
P. Ott ◽  
A. Bölcs ◽  
T. H. Fransson
Keyword(s):  
Shock Wave ◽  
Pressure Transducer ◽  
Numerical Study ◽  
Back Pressure ◽  
Time Dependent ◽  
Numerical Code ◽  
Phase Lag ◽  
Pressure Amplitude ◽  
Pressure Transducers ◽  
Unsteady Pressure

Investigations of flutter in transonic turbine cascades have shown that the movement of unsteady normal shocks has an important effect on the excitation of blades. In order to predict this phenomenon correctly, detailed studies concerning the response of unsteady blade pressures versus different parameters of an oscillating shock wave should be performed, if possible isolated from other flow effects in cascades. In the present investigation the correlation between an oscillating normal shock wave and the response of wall mounted time-dependent pressure transducers was studied experimentally in a nozzle with fluctuating back pressure. Excitation frequencies between 0 Hz and 180 Hz were investigated. For the measurements, various measuring techniques were employed. The determination of the unsteady shock position was made by a line scan camera using the Schlieren flow visualization technique. This allowed the simultaneous use of unsteady pressure transducers to evaluate the behavior of the pressure under the moving shock. A numerical code, based on the fully unsteady Euler equations in conservative form, was developed to simulate the behavior of the shock and the pressures. The main results of this work were: • The boundary layer over an unsteady pressure transducer has a quasi-steady behavior with respect to the phase lag. The pressure amplitude depends on the frequency of the back pressure. • For the geometry investigated the shock amplitude decreased with increasing excitation frequency. • The pressure transducer sensed the arriving shock before the shock had reached the position of the pressure transducer. • The computed unsteady phenomena agree well with the results of the measurements.

Toward Integrated Pressure Sensors for Temperatures up to 600°C

2016 ◽  
Vol 13 (4) ◽  
pp. 163-168
Author(s):  
Ayden Maralani ◽  
Levent Beker ◽  
Albert P. Pisano
Keyword(s):  
Pressure Transducer ◽  
Field Effect Transistors ◽  
Pressure Sensors ◽  
Harsh Environments ◽  
Test Results ◽  
Pressure Sensing ◽  
Pressure Transducers ◽  
Sensing Systems ◽  
Interface Circuitry ◽  
Type Pressure

The main objective of this study is to develop pressure-sensing systems by integrating pressure transducers with the interface circuitry in one package that can withstand harsh environments, particularly high temperatures up to 600°C. To achieve that, both pressure transducer and interface circuitry are individually required to operate and survive up to 600°C with acceptable degrees of reliability. This article reports performance evaluation of fabricated 4H-SiC Junction Field Effect Transistors along with differential pairs for use in the interface circuitry. The test results are very promising and show stable performances from 25°C up to 600°C. Moreover, design, fabrication, and early test (from 25°C up to 100°C) of an SiC-based circular diaphragm-type pressure transducer are also reported.

scholarly journals Experimental and Numerical Study of the Time-Dependent Pressure Response of a Shock Wave Oscillating in a Nozzle

1995 ◽  
Vol 117 (1) ◽  
pp. 106-114 ◽  
Author(s):  
P. Ott ◽  
A. Bo¨lcs ◽  
T. H. Fransson
Keyword(s):  
Shock Wave ◽  
Pressure Transducer ◽  
Numerical Study ◽  
Back Pressure ◽  
Time Dependent ◽  
Numerical Code ◽  
Phase Lag ◽  
Pressure Amplitude ◽  
Pressure Transducers ◽  
Unsteady Pressure

Investigations of flutter in transonic turbine cascades have shown that the movement of unsteady normal shocks has an important effect on the excitation of blades. In order to predict this phenomenon correctly, detailed studies concerning the response of unsteady blade pressures versus different parameters of an oscillating shock wave should be performed, if possible isolated from other flow effects in cascades. In the present investigation the correlation between an oscillating normal shock wave and the response of wall-mounted time-dependent pressure transducers was studied experimentally in a nozzle with fluctuating back pressure. Excitation frequencies between 0 Hz and 180 Hz were investigated. For the measurements, various measuring techniques were employed. The determination of the unsteady shock position was made by a line scan camera using the Schlieren flow visualization technique. This allowed the simultaneous use of unsteady pressure transducers to evaluate the behavior of the pressure under the moving shock. A numerical code, based on the fully unsteady Euler equations in conservative form, was developed to simulate the behavior of the shock and the pressures. The main results of this work were: (1) The boundary layer over an unsteady pressure transducer has a quasi-steady behavior with respect to the phase lag. The pressure amplitude depends on the frequency of the back pressure. (2) For the geometry investigated the shock amplitude decreased with increasing excitation frequency. (3) The pressure transducer sensed the arriving shock before the shock had reached the position of the pressure transducer. (4) The computed unsteady phenomena agree well with the results of the measurements.

Paper 2: Aerodynamic and Thermal Considerations in Designing Axial Flow Turbine Blades

1968 ◽  
Vol 183 (14) ◽  
pp. 11-19
Author(s):  
J. F. Barnes ◽  
J. Dunham
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Present Status ◽  
Turbine Blades ◽  
Axial Flow ◽  
Air Cooling ◽  
Aerodynamic Design ◽  
Aero Engines ◽  
Made In ◽  
Design Techniques

The first part of this paper reviews the progress made in improving the aerodynamic design of axial flow turbines and describes experience at the National Gas Turbine Establishment (N.G.T.E.) in the use of some of these techniques. The second part of the paper discusses the present status of internal air cooling for turbine blades and shows how some of the design techniques established for aero-engines might be exploited in the field of power generation.

Development and Removal of Alpha-Case Layer From Heat Treated Titanium Alloys

2017 ◽  
Author(s):  
Nikita Mohite ◽  
Sachin Biradar ◽  
Jyoti Shankar Jha ◽  
Sushil Mishra ◽  
Asim Tewari
Keyword(s):  
Oxide Layer ◽  
Elevated Temperatures ◽  
Fatigue Crack Initiation ◽  
Fixed Time ◽  
Hardness Profile ◽  
Air Cooling ◽  
Initiation Zone ◽  
Alpha Case ◽  
Heat Treated ◽  
Aero Engines

The components of the aero engines such as fan blades are generally manufactured from Titanium alloy forgings. At the elevated temperatures, the affinity of Titanium towards oxygen is very high, which results in formation of oxide layer on surface known as alpha-case layer. This alpha-case is both hard and brittle in nature which results in localized micro failure during its application. This gives rise to a fatigue crack initiation zone and compromises the integrity of the component, causing it to fail. To investigate this, Titanium α-β (Ti 64), α (Sn) and β (Mo) alloys were heat treated at 1010°C for 30min, 60min, 90min and 120min followed by air cooling. Formation of alpha-case layer in Ti-6Al-4V, Ti-Sn and Ti-Mo increased from 120.5μm to 391.1μm, 128.77μm to 443.23μm, 105.75μm to 262.46μm at 30mins and 120mins respectively. Chemical treatment, cathodic de-oxygenation, surface coating and laser ablation methods are generally used to remove the alpha case. In the current study, acid pickling is used to remove the alpha case layer, as this process is simple and also easily applicable to any complex shape of the material. In this method, samples were dipped in the solution of HF (5%) and HNO3 (35%) at 80 °C for fixed time at fixed intervals to find the rate of alpha case removal. Micro indentation was carried out to obtain hardness profile from surface to bulk of heat treated specimen. The quantification of alpha case oxide layer from surface to bulk was done by EDS.

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