scholarly journals Newly identified principle for aerodynamic heating in hypersonic flows

2018 ◽  
Vol 855 ◽  
pp. 152-180 ◽  
Author(s):  
Yiding Zhu ◽  
Cunbiao Lee ◽  
Xi Chen ◽  
Jiezhi Wu ◽  
Shiyi Chen ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Rayleigh Scattering ◽  
Pressure Sensors ◽  
Low Frequency ◽  
Fast Response ◽  
Aerodynamic Heating ◽  
Temperature Sensitive ◽  
Limited Region ◽  
Second Mode ◽  
Response Pressure

Instability evolution in a transitional hypersonic boundary layer and its effects on aerodynamic heating are investigated over a 260 mm long flared cone. Experiments are conducted in a Mach 6 wind tunnel using Rayleigh-scattering flow visualization, fast-response pressure sensors, fluorescent temperature-sensitive paint (TSP) and particle image velocimetry (PIV). Calculations are also performed based on both the parabolized stability equations (PSE) and direct numerical simulations (DNS). Four unit Reynolds numbers are studied, 5.4, 7.6, 9.7 and $11.7\times 10^{6}~\text{m}^{-1}$ . It is found that there exist two peaks of surface-temperature rise along the streamwise direction of the model. The first one (denoted as HS) is at the region where the second-mode instability reaches its maximum value. The second one (denoted as HT) is at the region where the transition is completed. Increasing the unit Reynolds number promotes the second-mode dissipation but increases the strength of local aerodynamic heating at HS. Furthermore, the heat generation rates induced by the dilatation and shear processes (respectively denoted as $w_{\unicode[STIX]{x1D703}}$ and $w_{\unicode[STIX]{x1D714}}$ ) were investigated. The former item includes both the pressure work $w_{\unicode[STIX]{x1D703}1}$ and dilatational viscous dissipation $w_{\unicode[STIX]{x1D703}2}$ . The aerodynamic heating in HS mainly arose from the high-frequency compression and expansion of fluid accompanying the second mode. The dilatation heating, especially $w_{\unicode[STIX]{x1D703}1}$ , was more than five times its shear counterpart. In a limited region, the underestimated $w_{\unicode[STIX]{x1D703}2}$ was also larger than $w_{\unicode[STIX]{x1D714}}$ . As the second-mode waves decay downstream, the low-frequency waves continue to grow, with the consequent shear-induced heating increasing. The latter brings about a second, weaker growth of surface-temperature HT. A theoretical analysis is provided to interpret the temperature distribution resulting from the aerodynamic heating.

The influence of wavy wall on hypersonic boundary layer instability over a flared cone

2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040093
Author(s):  
Wufei Si
Keyword(s):  
Boundary Layer ◽  
Rayleigh Scattering ◽  
Local Heating ◽  
Pressure Sensors ◽  
Fast Response ◽  
Aerodynamic Heating ◽  
Hypersonic Boundary Layer ◽  
Wavy Wall ◽  
Smooth Wall ◽  
Boundary Layer Instability

The influence of wavy wall on the hypersonic boundary layer instability and the related aerodynamic heating are investigated over a flared cone. Experiments are conducted in a Mach 6 wind tunnel using Rayleigh-scattering flow visualization, fast-response pressure sensors and infrared thermography. Three sizes of wavy wall have been placed on the model in comparison with the smooth wall cone. The results show that compared to the smooth-wall cone, all the wavy-wall cones can suppress the second-mode instability to a certain degree and eliminate the local heating spot before transition is completed. Also, it is found that with the decrease of wavy wall wavelength, the transition location is shifted downstream.

Development of a Centrifugal Compressor Facility for Performance and Aeromechanics Research

2016 ◽  
Author(s):  
Fangyuan Lou ◽  
Herbert M. Harrison ◽  
John C. Fabian ◽  
Nicole L. Key ◽  
Darrell K. James ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Sensors ◽  
Fast Response ◽  
Tool Development ◽  
Research Facility ◽  
Inlet Distortion ◽  
Compressor Inlet ◽  
Response Pressure ◽  
Development And Validation ◽  
Clearance Control

This paper details the development of a Single Stage Centrifugal Compressor (SSCC) research facility at Purdue University in collaboration with Honeywell. The research vehicle is a Honeywell experimental compressor that has been specifically outfitted with a variety of instrumentation for research purposes. Both steady-state and fast-response instrumentation will be used to provide benchmark experimental data for performance and aeromechanics tool development and validation. Some unique facility aspects include real-time clearance control, active bleed flow management, fast-response pressure sensors embedded in the impeller, and a full circumferential traverse at the compressor inlet to facilitate inlet distortion quantification. The details of the facility and baseline results are presented.

Using Blade Tip Timing and Pressure Data to Characterise Compressor Stall and Surge

2020 ◽  
Author(s):  
Radoslaw Przysowa ◽  
Peter Russhard ◽  
Michal Wachlaczenko
Keyword(s):  
Complex Analysis ◽  
Pressure Sensors ◽  
Fast Response ◽  
Rotating Stall ◽  
Turbine Engine ◽  
Practical Applications ◽  
Flow Disturbances ◽  
Blade Tip ◽  
Response Pressure ◽  
The Cost

Abstract Rotating stall and surge are common phenomena in compressors, and related research has been carried out since the invention of the gas-turbine engine. Signals of fast response pressure sensors analysed with spectral methods based on Fourier transform are primarily used to characterise compressor stall. This article focuses on the application of blade tip timing (BTT) for this purpose and aims to demonstrate current analysis capabilities, issues and challenges related to practical applications. By using real engine test results, we show that BTT provides more information at the cost of more complex analysis. The signals of four tip timing and three pressure probes installed in the first compressor stage are processed. We observed flow disturbances and blade responses caused by objects located in the inlet at a constant speed and also surge events during snap acceleration. All-blade spectrum and modal tracking are used to identify the presence of non-integral vibration and to determine the nominal frequency and nodal diameter. This data seeds the Least Squares Fitting, which delivers amplitude and phase. A method for sensor fusion is presented. For the selected non-integral responses, tip timing and pressure results are evaluated to show how they can complement each other. The proposed methodology can be used both for compressor development and Blade Health Monitoring.

scholarly journals Spatial and temporal resolution of a fast-response aerodynamic pressure probe in grid-generated turbulence

2021 ◽  
Vol 62 (2) ◽  
Author(s):  
Florian M. Heckmeier ◽  
Stefan Hayböck ◽  
Christian Breitsamter
Keyword(s):  
Temporal Resolution ◽  
Pressure Sensors ◽  
Mesh Size ◽  
Reynolds Numbers ◽  
Fast Response ◽  
Pressure Probe ◽  
Aerodynamic Pressure ◽  
Kolmogorov Length Scale ◽  
High Bandwidth ◽  
Velocity Spectra

Abstract The spatial and temporal resolution of a fast-response aerodynamic pressure probe (FRAP) is investigated in a benchmark flow of grid-generated turbulence. A grid with a mesh size of $$M=6.4$$ M = 6.4 mm is tested for two different free-stream velocities, hence, resulting in Reynolds numbers of $$Re_M= \{4300,12800\}$$ R e M = { 4300 , 12800 } . A thorough analysis of the applicability of the underlying assumptions with regard to turbulence isotropy and homogeneity is carried out. Taylor’s frozen turbulence hypothesis is assumed for the calculation of deducible flow quantities, like the turbulent kinetic energy or the dissipation rate. Furthermore, besides the examination of statistical quantities, velocity spectra of measurements downstream of the grid are quantified. Results of a small fast-response five-hole pressure probe equipped with piezo-resistive differential pressure sensors are compared to single-wire hot-wire constant temperature anemometry data for two different wire lengths. Estimates of temporal and spatial turbulent scales (e.g., Taylor micro scale and Kolmogorov length scale) show good agreement to data in the literature but are affected by filtering effects. Especially in the energy spectra, very high bandwidth content cannot be resolved by the FRAP, which is mainly due to bandwidth limits in the temporal calibration of the FRAP and the minimal resolution of the integrated sensors. Graphic abstract

scholarly journals Identification and Characterization of Genes That Interact With lin-12 in Caenorhabditis elegans

Genetics ◽  
1997 ◽  
Vol 147 (4) ◽  
pp. 1675-1695 ◽  
Author(s):  
Frans E Tax ◽  
James H Thomas ◽  
Edwin L Ferguson ◽  
H Robert Horvitzt
Keyword(s):  
Cell Fate ◽  
Low Frequency ◽  
Signal Transduction Pathway ◽  
Temperature Shift ◽  
Egg Laying ◽  
Null Alleles ◽  
Temperature Sensitive ◽  
Loss Of Function ◽  
Gain Of Function ◽  
Suppressor Mutations

Abstract We identified and characterized 14 extragenic mutations that suppressed the dominant egg-laying defect of certain lin-12 gain-of-function mutations. These suppressors defined seven genes: sup-l7, lag-2, sel-4, sel-5, sel-6, sel-7 and sel-8. Mutations in six of the genes are recessive suppressors, whereas the two mutations that define the seventh gene, lag-2, are semi-dominant suppressors. These suppressor mutations were able to suppress other lin-12 gain-of-function mutations. The suppressor mutations arose at a very low frequency per gene, 10-50 times below the typical loss-of-function mutation frequency. The suppressor mutations in sup1 7 and lag-2 were shown to be rare non-null alleles, and we present evidence that null mutations in these two genes cause lethality. Temperature-shift studies for two suppressor genes, sup1 7and lag-2, suggest that both genes act at approximately the same time as lin-12in specifying a cell fate. Suppressor alleles of six of these genes enhanced a temperature-sensitive loss-of-function allele of glp-1, a gene related to lin-12 in structure and function. Our analysis of these suppressors suggests that the majority of these genes are part of a shared lin-12/glp-1 signal transduction pathway, or act to regulate the expression or stability of lin-12 and glp-1.

High-output diesel engine heat transfer: Part 1 - comparison between piston heat flux and global energy balance

2021 ◽  
pp. 146808742110170
Author(s):  
Eric Gingrich ◽  
Michael Tess ◽  
Vamshi Korivi ◽  
Jaal Ghandhi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Diesel Engine ◽  
Surface Temperature ◽  
Fast Response ◽  
Temperature Data ◽  
Start Of Injection ◽  
Local Measurements ◽  
Surface Temperature Data ◽  
High Output

High-output diesel engine heat transfer measurements are presented in this paper, which is the first of a two-part series of papers. Local piston heat transfer, based on fast-response piston surface temperature data, is compared to global engine heat transfer based on thermodynamic data. A single-cylinder research engine was operated at multiple conditions, including very high-output cases – 30 bar IMEPg and 250 bar in-cylinder pressure. A wireless telemetry system was used to acquire fast-response piston surface temperature data, from which heat flux was calculated. An interpolation and averaging procedure was developed and a method to recover the steady-state portion of the heat flux based on the in-cylinder thermodynamic state was applied. The local measurements were spatially integrated to find total heat transfer, which was found to agree well with the global thermodynamic measurements. A delayed onset of the rise of spatially averaged heat flux was observed for later start of injection timings. The dataset is internally consistent, for example, the local measurements match the global values, which makes it well suited for heat transfer correlation development; this development is pursued in the second part of this paper.

scholarly journals Estimation of the Noise Source Level of a Commercial Ship Using On-Board Pressure Sensors

2021 ◽  
Vol 11 (3) ◽  
pp. 1243
Author(s):  
Hongseok Jeong ◽  
Jeung-Hoon Lee ◽  
Yong-Hyun Kim ◽  
Hanshin Seol
Keyword(s):  
Noise Source ◽  
Pressure Sensors ◽  
Low Frequency ◽  
Frequency Resolution ◽  
Source Strength ◽  
Recording Time ◽  
Source Level ◽  
The One ◽  
Hydrophone Array ◽  
Good Agreement

The dominant underwater noise source of a ship is known to be propeller cavitation. Recently, attempts have been made to quantify the source strength using on-board pressure sensors near the propeller, as this has advantages over conventional noise measurement. In this study, a beamforming method was used to estimate the source strength of a cavitating propeller. The method was validated against a model-scale measurement in a cavitation tunnel, which showed good agreement between the measured and estimated source levels. The method was also applied to a full-scale measurement, in which the source level was measured using an external hydrophone array. The estimated source level using the hull pressure sensors showed good agreement with the measured one above 400 Hz, which shows potential for noise monitoring using on-board sensors. A parametric study was carried out to check the practicality of the method. From the results, it was shown that a sufficient recording time is required to obtain a consistent level at high frequencies. Changing the frequency resolution had little effect on the result, as long as enough data were provided for the one-third octave band conversion. The number of sensors affected the mid- to low-frequency data.

The Effect of the Operating Point on the Pressure Fluctuations at the Blade Passage Frequency in the Volute of a Centrifugal Pump

2002 ◽  
Vol 124 (3) ◽  
pp. 784-790 ◽  
Author(s):  
Jorge L. Parrondo-Gayo ◽  
Jose´ Gonza´lez-Pe´rez ◽  
Joaquı´n Ferna´ndez-Francos
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuations ◽  
Fast Response ◽  
Strong Increase ◽  
Flow Rates ◽  
Blade Passage ◽  
Pressure Transducers ◽  
Leading Role ◽  
Dynamic Forces ◽  
Response Pressure

An experimental investigation is presented which analyzes the unsteady pressure distribution existing in the volute of a conventional centrifugal pump with a nondimensional specific speed of 0.48, for flow-rates from 0% to 160% of the best-efficiency point. For that purpose, pressure signals were obtained at 36 different locations along the volute casing by means of fast-response pressure transducers. Particular attention was paid to the pressure fluctuations at the blade passage frequency, regarding both amplitude and phase delay relative to the motion of the blades. Also, the experimental data obtained was used to adjust the parameters of a simple acoustic model for the volute of the pump. The results clearly show the leading role played by the tongue in the impeller-volute interaction and the strong increase in the magnitude of dynamic forces and dipole-like sound generation in off-design conditions.

Analysis of pulsating flow measurement of engine exhaust by a Pitot tube flowmeter

2005 ◽  
Vol 6 (1) ◽  
pp. 85-93 ◽  
Author(s):  
H Nakamura ◽  
I Asano ◽  
M Adachi ◽  
J Senda
Keyword(s):  
Fast Response ◽  
Differential Pressure ◽  
Pulsating Flow ◽  
Pitot Tube ◽  
Engine Exhaust ◽  
Idle Speed ◽  
Pressure Transducers ◽  
Vehicle Engine ◽  
Before And After ◽  
Response Pressure

The Pitot tube flowmetering technique has been used to measure pulsating flow from a vehicle engine exhaust. In general, flowmetering techniques that utilize differential pressure measurements based on Bernoulli's theory are likely to show erroneous readings when measuring an average flowrate of pulsating flow. The primary reason for this is the non-linear relationship between the differential pressure and the flowrate; i.e. the flowrate is proportional to the square root of the differential pressure. Therefore, an average of the differential pressure does not give an average of pulsating flow. In this study, fast response pressure transducers have been used to measure the pulsating pressure. Then the pulsating differential pressure is converted to the flowrate while keeping the pulsation unaveraged. An average flowrate is then calculated in the flowrate domain in order to maintain linearity before and after averaging. The peak amplitude of a pulsation measured here was about 1800 L/min at an average flowrate of 70 L/min when the engine ran at idle speed. This measurement has been confirmed by measuring the pulsation with a gas analyser. The results show a large amount of back and forth gas movement in the exhaust tube. This magnitude of pulsation can cause as much as five times higher erroneous results with the pressure domain averaging when compared to a flowrate domain averaging.

Experimental Investigation of Surge Phenomena in a Transonic Centrifugal Compressor With Inlet Distortion

2020 ◽  
Author(s):  
Sasuga Ito ◽  
Masato Furukawa ◽  
Satoshi Gunjishima ◽  
Takafumi Ota ◽  
Kazuhito Konishi ◽  
...  
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Flow Instability ◽  
Pressure Sensors ◽  
Low Flow ◽  
Inlet Distortion ◽  
Transonic Centrifugal Compressor ◽  
Response Pressure ◽  
Surge Phenomena ◽  
Low Flow Rate

Abstract Inlet distortion has influence on the aerodynamic performance of turbomachinery such as compressors, turbines and fans. On turbochargers, bent pipes are installed around the compressor due to the spatial limitations in the engine room of the vehicle. As the result, the compressor is operated with the distorted inflow. In the low flow rate operation, the distorted inflow also affects the flow instability like stall and surge. Especially, the operation range on the low flow rate side is defined based on the flow rate where surge occurs, so it is important to investigate the effect of the distorted inflow on surge. In this study, the effect of the inlet distortion to surge phenomena has been investigated by the experiments with a transonic centrifugal compressor. A bent pipe has been installed at the upstream of the compressor to generate a distorted flow. Experiments have been also conducted under the condition that a straight pipe was installed upstream of the compressor, and unsteady measurements with high response pressure sensors and an I-type hot wire probe have been carried out to each experiments. In addition, Fast Fourier transform (FFT) and Wavelet transform have been applied to the unsteady measurement results obtained from each experiment.

Sign in / Sign up

Export Citation Format

Share Document