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Design charts which predict acoustic absorption of porous insulators were verified experimentally using the two-microphone technique to measure the normal incidence absorption coefficient of three glass fiber materials in two different arrangements - a single-layer sample and a single layer in front of an air space, each backed by a rigid termination. The specific flow resistivities of the materials ranged from 2,000 to 52,000 mks rayls/m. Experimentally determined absorption coefficients were in agreement with those predicted by the design charts. The results indicate that these charts could be a useful tool in designing sound absorbers for practical applications.

A distributed parameter mathematical model of a complete power steering hydraulic transmission circuit has been developed and implemented on a personal computer to analyze the effect of tuning cables on the attenuation of pressure waves generated by the pump. Tuning cables, flexible tubes positioned coaxially inside a length of hose placed at a convenient location in the circuit, reduce fluidborne noise primarily by destructive interference and viscous damping. The model uses a transfer matrix approach that includes two-dimensional viscous flow and three-dimensional fluid-structure interaction. It can be used for sizing and positioning tuning cable devices in power steering as well as other hydraulic systems prior to verification testing of the circuit.

An experiment which simulates operating conditions in a diesel engine cylinder head which are favorable for initiation of nucleate boiling is described and the relationship between heat flux and coolant passage wall temperature is presented. Measurements of temperatures in the head between the flame face and the coolant passages indicated nucleate boiling may initiate within the valve bridge at a wall temperature of approximately 393 K; however, forced convection was the dominant mode of heat transfer. The results compare favorably with J. C. Chen's heat transfer correlation which accounts for forced convection and nucleate boiling.