Error Estimation of Measured Exhaust Gas Temperature in Afterburner Mode in an Aero Gas Turbine Engine

In a turbofan engine, thrust is a key parameter which is measured or estimated from various parameters acquired during engine testing in an engine testbed. Exhaust Gas Temperature (EGT) is the most critical parameter used for thrust calculation. This work presents a novel way to measure and correct the errors in EGT measurement. A temperature probe is designed to measure EGT in the engine jet pipe using thermocouples. The temperature probe is designed to withstand the mechanical and temperature loads during the operation. Structural analysis at the design stage provided a strength margin of 90% and eigenfrequency margin of more than 20%. Thermal analysis is carried out to evaluate maximum metal temperature. Errors are quite high in high-temperature measurements which are corrected using the available methodologies. The velocity error, conduction error, and radiation error are estimated for the measured temperature. The difference of 97 K between the measured gas temperature and calculated gas temperature from measured thrust is explained. The estimated velocity error is 1 K, conduction error is 3 K, and radiation error is 69 K. Based on the error estimation, the measurement error is brought down to 24 K. After applying the above corrections, the further difference of 24 K between measured and estimated value can be attributed to thermocouple error of +/-0.4% of the reading for class 1 accuracy thermocouple, other parameter measurement errors, and analysis uncertainties. The present work enables the designer to calculate the errors in high-temperature measurement in a turbofan engine.

Optimal Experimental Design for Inverse Identification of Conductive and Radiative Properties of Participating Medium

The conductive and radiative properties of participating medium can be estimated by solving an inverse problem that combines transient temperature measurements and a forward model to predict the coupled conductive and radiative heat transfer. The procedure, as well as the estimates of parameters, are not only affected by the measurement noise that intrinsically exists in the experiment, but are also influenced by the known model parameters that are used as necessary inputs to solve the forward problem. In the present study, a stochastic Cramér–Rao bound (sCRB)-based error analysis method was employed for estimation of the errors of the retrieved conductive and radiative properties in an inverse identification process. The method took into account both the uncertainties of the experimental noise and the uncertain model parameter errors. Moreover, we applied the method to design the optimal location of the temperature probe, and to predict the relative error contribution of different error sources for combined conductive and radiative inverse problems. The results show that the proposed methodology is able to determine, a priori, the errors of the retrieved parameters, and that the accuracy of the retrieved parameters can be improved by setting the temperature probe at an optimal sensor position.

The Use of Induction Heating in Assessing the Technical Condition and Operating Intervals in Producing Wells

The paper considers two approaches based on the use of an induction heater: the first is a "large thermal anemometer", in which the casing is heated by induction action and the problem of determining column flows, determining the flow rate and the inflow profile is solved by analyzing the formation of thermal labels (Valiullin et al., 2001, Valiullin et al., 2002), the second is a "small radial-azimuth thermal anemometer - small thermal anemometer", where an induction heater is used to heat the element of the thermal anemometer. In the second case, the problem of estimating the flow direction and estimating the flow rate is solved. For the first approach, "large thermal anemometer", the results of theoretical and experimental studies of the temperature field distribution in a physical model as close as possible to the design of a real oil well, with induction heating of the column taking into account the column flow of liquid. The influence of forced convection on the readings of temperature sensors with different locations in the well (pressed against the inner wall of the column, along the axis of the device) is studied. The advantages of the azimuthal location of temperature sensors when measuring temperature anomalies of the column motion of a liquid are shown. It is established that with the help of an azimuthally distributed temperature probe, it is possible to determine the column flow "from above" when measuring above and below the heating point of the inductor. The optimal time intervals for measuring the temperature at which the allocation of channels for the column movement of the liquid is most effective are determined. For the second approach, "small thermal anemometer", the design features of a borehole thermoconductive indicator of the inflow of indirect heating, which is heated using an induction heater, are considered. Using an induction heater, a uniform heating of the housing of the borehole thermoconductive inflow indicator is achieved. Due to the developed design, the sensor is able to detect the presence of a liquid flow directed perpendicular to the body, and determine the direction of this flow. The "large thermal anemometer" technology has been tested, which has shown its effectiveness and prospects for using it to determine backwater flows (column circulation), but there are still questions related to assessing the effect of thermal convection on the recorded temperature and the possibility of diagnosing the column circulation channel (Valiullin et al., 2017). The article (Valiullin et al., 2008) describes the developed equipment of the "active thermometry" method for conducting geophysical studies of wells, while the classical location of temperature sensors along the axis of the device is used in the borehole probe, which does not make it possible to determine the channels of the circulation channels. The sensors located in this way are more susceptible to the influence of thermal convection, while the change in the velocity and composition of the fluid can be estimated as the presence of circulation channel. In this regard, work was carried out to reduce the influence of convection, the design of the temperature probe was developed, which allows minimizing the influence of thermal convection and increasing the efficiency of the allocation of circulation channel. Thermoanemometers, better known as thermoanemometer sensors (borehole thermoconductive inflow indicator), have been widely used in field geophysics (Zhuvagin et al., 1973). The traditional sensor of a thermal anemometer, with all its advantages, is not without disadvantages, and one of these is the inability to unambiguously determine the presence and direction of the fluid flow directed perpendicular to its body. The solution of this problem would allow, along with the known solved problems, to increase the information content of the thermoanemometer sensor, namely, in terms of detecting the leakiness of the column, evaluating the operating intervals at low debits, the flow direction. This problem is solved in this work on the basis of the use of an indirect induction heater.

Effects of probes with different structures on the flow field and measurement results of imported compressors

In this paper, the measurement accuracy of two different types of total pressure probe and total temperature probe in turboshaft engine compressor inlet channel and the influence of these two probes on the flow field through numerical simulation was studied. At the same time, the influence of the probe structure and installation position on probe measurement results under three typical working conditions of cruise, maximum continuous and takeoff was analyzed. The simulation results showed that the higher the engine inlet flow rate, the greater the measurement error of the probe. Comparing with the total temperature probe, the total pressure probe measurement accuracy is more influenced by the flow rate. The velocity uniformity is less affected by the engine operating conditions and is mainly related to the structure of the inserted probes. The closer the total pressure probe to the support plate, the greater the measurement error. The probe installation position has a small effect on the total pressure loss coefficient at the outlet.

Fluorescence Anisotropy Studies of Fluorescein

Fluorescein anisotropy, which is a widely used technique to study the folding state of proteins or affinity of ligands, is used in the present work to study the temperature sensing of fluid in a microchannel, by adding fluorophore in the fluid. Fluorescein was used as a temperature probe, while glycerol-aq. ammonia was used as a working fluid. Fluorescence anisotropy of fluorescein were measured by varying various parameters. Apart from this, a comparison of fluorescence anisotropy and fluorescence intensity is also performed.

Comparison of a Smartfin with an Infrared Sea Surface Temperature Radiometer in the Atlantic Ocean

The accuracy and precision of satellite sea surface temperature (SST) products in nearshore coastal waters are not well known, owing to a lack of in-situ data available for validation. It has been suggested that recreational watersports enthusiasts, who immerse themselves in nearshore coastal waters, be used as a platform to improve sampling and fill this gap. One tool that has been used worldwide by surfers is the Smartfin, which contains a temperature sensor integrated into a surfboard fin. If tools such as the Smartfin are to be considered for satellite validation work, they must be carefully evaluated against state-of-the-art techniques to quantify data quality. In this study, we developed a Simple Oceanographic floating Device (SOD), designed to float on the ocean surface, and deployed it during the 28th Atlantic Meridional Transect (AMT28) research cruise (September and October 2018). We attached a Smartfin to the underside of the SOD, which measured temperature at a depth of ∼0.1 m, in a manner consistent with how it collects data on a surfboard. Additional temperature sensors (an iButton and a TidbiT v2), shaded and positioned a depth of ∼1 m, were also attached to the SOD at some of the stations. Four laboratory comparisons of the SOD sensors (Smartfin, iButton and TidbiT v2) with an accurate temperature probe (±0.0043 K over a range of 273.15 to 323.15 K) were also conducted during the AMT28 voyage, over a temperature range of 290–309 K in a recirculating water bath. Mean differences (δ), referenced to the temperature probe, were removed from the iButton (δ=0.292 K) and a TidbiT v2 sensors (δ=0.089 K), but not from the Smartfin, as it was found to be in excellent agreement with the temperature probe (δ=0.005 K). The SOD was deployed for 20 min periods at 62 stations (predawn and noon) spanning 100 degrees latitude and a gradient in SST of 19 K. Simultaneous measurements of skin SST were collected using an Infrared Sea surface temperature Autonomous Radiometer (ISAR), a state-of-the-art instrument used for satellite validation. Additionally, we extracted simultaneous SST measurements, collected at slightly different depths, from an underway conductivity, temperature and depth (CTD) system. Over all 62 stations, the mean difference (δ) and mean absolute difference (ϵ) between Smartfin and the underway CTD were −0.01 and 0.06 K respectively (similar results obtained from comparisons between Smartfin and iButton and Smartfin and TidbiT v2), and the δ and ϵ between Smartfin and ISAR were 0.09 and 0.12 K respectively. In both comparisons, statistics varied between noon and predawn stations, with differences related to environmental variability (wind speed and sea-air temperature differences) and depth of sampling. Our results add confidence to the use of Smartfin as a citizen science tool for evaluating satellite SST data, and data collected using the SOD and ISAR were shown to be useful for quantifying near-surface temperature gradients.