Scaling Interface Length Increase Rates in Richtmyer– Meshkov Instabilities

The interface area increase produced by large-amplitude wave refraction through an interface that separates fluids with different densities can have important physiochemical consequences, such as a fuel consumption rate increase in the case of a shock–flame interaction. Using the results of numerical simulations along with a scaling analysis, a unified scaling law of the interface length increase was developed applicable to shock and expansion wave refractions and both types of interface orientation with the respect to the incoming wave. To avoid a common difficulty in interface length quantification in the numerical tests, a sinusoidally perturbed interface was generated using gases with different temperatures. It was found that the rate of interface increase correlates almost linearly with the circulation deposited at the interface. When combined with earlier developed models of circulation deposition in Richtmyer–Meshkov instability, the obtained scaling law predicts dependence of interface dynamics on the basic problem parameters

Flammability limits of carbon monoxide and carbon monxide-hydrogen mixtures in air at elevated temperatures

Bibliography: p. 84-94

Pressure-wave amplification of flame area in wave rotor channels

Recent interest in novel engine concepts such as the wave rotor combustor highlighted the need for better understanding of the shock-flame and expansion wave-flame interaction phenomena. For the optimum design of such devices, dependence of flame area change on the wave and flame parameters should be well understood. To gain the understanding of flame area increase following shock or expansion wave passage, baroclinic vortex sheet layer generation was analyzed both analytically and numerically. It was found that for weak waves or small angles, the vortex sheet strengths were nearly equal in magnitude for shocks and expansion waves of equal pressure ratio. The difference between vortex sheet strengths for expansion waves and shocks of equal pressure ratio increased with shock strength. The vortex sheet strength for expansion waves was 50% lower than for shocks, for pressure ratios over 20. After vortex sheet production was examined, the flame area increase was investigated following shock or expansion wave passage through a sinusoidal interface. It was found that the density interface length grows almost linearly for a time period significantly exceeding the time of the linear perturbation amplitude growth. Significantly faster interface growth rates were observed when the shock or expansion wave approached the interface from the hot gas side (called fast/slow interaction based on the relative speed of sound across the interface). The result is opposite to that expected from Richtmyer-Meshkov theory. Finally, the interface length increase and its contribution to the overall fuel consumption rate increase produced by the shock or expansion wave passage were investigated. The results showed that the flame area increase plays a dominant role in the total fuel consumption rate increase with relatively weak shocks (shock Mach number 1.1 – 1.5) and expansion waves (pressure ratio of 1.245) for reactive mixtures at room temperature. With stronger shocks, its relative contribution may become smaller than that of the chemical kinetic amplification, depending on initial gas temperature

A study of person-job fit in front office employees in midwestern hotels

The main goal of this work is to study the interaction between personality and organization, known as person-environment fit, and the extent to which the right fit can improve the selection process within the hospitality industry. It will examine the compatibility of individuals to the given environment from the point of view of job demands, more specifically person-job fit. Though prevalent in management and psychology fields for many years, person-job fit has never been explored in the context of the hospitality industry. Its popularity in other sciences and industries comes from the fact that person-job fit, broadly defined as the match between individual knowledge, skills and abilities (KSA) and demands of the job, has been found to be an important tool in personnel selection. This study is the first attempt to justify the use of person-job fit as an effective and powerful tool for selection of nonmanagerial hotel employees. This study focuses on front-office employees as representative group of non-managerial hotel employees. The results of multiple regression analysis in this study identified a significant relationship between the categories of person-job fit (knowledge; skills and abilities; attitudes towards work preferences; attitudes towards service orientation; attitudes towards positive problem solving; and attitudes towards change) on the one side and job satisfaction and intent to quit on the other side in front office employees. Job satisfaction was found to be a good predictor for the intent to quit in front office employees. Also, no difference was found between an established person-job fit test by Cable and DeRue (2005) and Hospitality Perceived Person-job Fit (HPPJF) survey, created for this study. Results from this study suggest that person-job fit is an effective predictor of post-entry outcome variables in front office hospitality employees. Adding person-job fit to the selection process will help to identify service-oriented front office employees with the knowledge, skills, abilities, and attitudes necessary to perform their everyday responsibilities and help to eliminate those upfront who are most likely to leave the job