Acoustic Analysis of Sensor Ports

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Acoustic Analysis of Sensor Ports

Acquiring data in rocket engines that is representative of the actual dynamic environment can often be difficult due to a multitude of influences. One source of contamination that is often not considered entirely is the response associated with the acoustic cavity created by a sensor offset. It is common to offset a sensor due to various reasons such as for mounting accessibility, thermal isolation, shock reduction, or prevention of debris impingement. While estimating the natural frequency of the acoustic cavity is straightforward, limited analysis has been described on the determination of the overall frequency response. The sensor port design approach usually attempts to ensure the port is short enough such that the acoustic response is negligible near the frequency-of-interest, but this requires knowledge of the frequency response and simple rules-of-thumb are not always guaranteed. Data correction and/or data interpretation is also often desired for an unsatisfactory response. The limited response analysis in the literature only offers approximations or neglects important contributions. A new approach is devised theoretically and computationally that captures the true acoustic response of a sensor port. This paper summarizes the acoustics background, the port response theoretical development, and provides comparisons of a port acoustic response using an analytical model and computational acoustics. The effects of nonlinear acoustics are also examined. Additionally, the paper summarizes the design of a specialized filter using the predicted sensor port response that can be applied to data for correction

Study on Pumping System Design for Water Injection

The Objective of this project is to study the types of water injection pumping system and their performance, related to deepwater reservoirs and to analyze the pressure maintenance effectiveness using ECLPISE100 reservoir simulator

Off-peak summer performance enhancement for rows of fixed solar thermal collectors using reflective surfaces

The possibility of increasing the efficiency of fixed solar thermal collectors without greatly adding to the cost or complexity of the overall solar collection system was studied. The focus was on the use of flat mirrors, which would accomplish this goal by capturing the morning sunlight during the summer non-peak solar collection time while maintaining the balance of the system within its existing design specifications, allowing the system to perform at a higher capacity factor. A 150kWt solar heating and cooling system operates within the Mechanical Engineering Building at the University of New Mexico and was the basis for a simulation model and validation testing. The use of flat mirrors to increase solar energy collection is a cheaper alternative to the purchase of additional solar collectors and results show that the reflectors, properly installed on a solar thermal collection system, can reduce the cost of cooling by 20% without further modification to the existing system

New nonlinear approaches for the adjustment and updating of a SAM

We believe that any adjustment and updating process (AUP) should try to minimize the relative deviation of the new coefficients from the intial ones in a homogeneus way. This homogenity would mean that the magnitude of this relative deviation is similar among the elements of each row or column, therefor avoiding the concentration of the changes in particular cells of the SAM. In this work, we propose some new adjustment criteria in order to obtain a homogeneus relative adjustment of the sructural coefficients. We also test the usefulness of this proposal by comparing its results with the ones obtained with more standard approaches.nonlinear approaches SAM

High Frequency Acoustic Response Characterization and Analysis of the Deep Throttling Common Extensible Cryogenic Engine

The Common Extensive Cryogenic Engine program demonstrated the operation of a deep throttling engine design. The program, spanning five years from August 2005 to July 2010, funded testing through four separate engine demonstration test series. Along with successful completion of multiple objectives, a discrete response of approximately 4000 Hz was discovered and explored throughout the program. The typical low-amplitude acoustic response was evident in the chamber measurement through almost every operating condition; however, at certain off-nominal operating conditions, the response became discrete with higher amplitude. This paper summarizes the data reduction, characterization, and analysis of the 4,000 Hz response for the entire program duration, using the large amount of data collected. Upon first encountering the response, new objectives and instrumentation were incorporated in future test series to specifically collect 4,000 Hz data. The 4,000 Hz response was identified as being related to the first tangential acoustic mode by means of frequency estimation and spatial decomposition. The latter approach showed that the effective node line of the mode was aligned with the manifold propellant inlets with standing waves and quasi-standing waves present at various times. Contour maps that contain instantaneous frequency and amplitude trackings of the response were generated as a significant improvement to historical manual approaches of data reduction presentation. Signal analysis and dynamic data reduction also uncovered several other features of the response including a stable limit cycle, the progressive engagement of subsequent harmonics, the U-shaped time history, an intermittent response near the test-based neutral stability region, other acoustic modes, and indications of modulation with a separate subsynchronous response. Although no engine damage related to the acoustic mode was noted, the peak-to-peak fluctuating pressure amplitude achieved 12.1% of the mean chamber pressure at its highest. The identification of this response in terms of an instability is also discussed

Path Integral Monte Carlo for Entanglement in Bosonic Lattices at T = 0

Path-Integral Monte Carlo Worm Algorithm is one of many Quantum Monte Carlo (QMC) methods that serve as powerful tools for the simulation of quantum many-body systems. Developed in the late 90’s, this algorithm has been used with great success to study a wide array of physical models where exact calculation of observables is not possible due to the exponential size of the Hilbert space. One type of systems that have eluded PIMC-WA implementation are lattice models at zero temperature, which are of relevance in experimental settings, such as in optical lattices of ultra-cold atoms. In this thesis, we develop a PIMC Worm Algorithm for the simulation of interacting bosonic lattices at zero temperature. The algorithm is benchmarked with exact diagonalization by computing conventional estimators, such as kinetic and potential energies, and also quantum entanglement estimators. We implement our algorithm to numerically confirm new finite-size scaling forms that we derive for various entanglement measures, such as the operationally accessible, and symmetry- resolved Rényi entropies in the Bose-Hubbard model. We finalize by introducing a method for the direct sampling of two dimensional truncated exponential distribution for the reduction of autocorrelation times, an example of the algorithmic development that will be needed moving forward to expand the applicability of our algorithm to even more complex systems