SBIR-STTR Award

In this project we propose to demonstrate the feasibility of an external pipe sensor for measuring sound pressure levels in submarine piping systems. The sensor consists of flexible PVDF wire wrapped a number of integral turns around the pipe exterior. The charge/voltage output of the sensor can be shown to be directly proportional and highly sensitive to the amplitude of the contained fluid pulsation wave. Previous work by one of key team members of the proposal has both analytically and experimentally demonstrated the potential of PVDF wire sensors for measuring low level interior sound pressures in piping systems. These low level sound pressure induced motions are undetectable to the desired sensitivity and accuracy with traditional accelerometers. In Phase I, analytical simulation tools will be developed to model the fluid filled piping system and externally attached PVDF wire sensor. The model will be used to determine the optimum sensor arrangement, design sensitivity, accuracy and SNR. Finite Element models will investigate the influence of realistic piping characteristics on sensor performance. Optional tasks for constructing a basic piping test rig and preliminary testing of a PVDF wire sensor are also included.

Benefit:
Successful execution of this project will result in an immediate and widespread use of PVDF sensors for detection and measurement of interior pipe acoustic pressure levels for US commercial and general military industries. From the military perspective, the outcome will be an external PVDF wire sensor for accurately measuring the internal pressure in fluid filled piping systems in a cost effective, compact, robust configuration with minimal integration issues suitable for submarines and surface ships. Other commercial applications can also be realized in the nuclear power and aerospace industry where the PVDF sensor could be used for improved monitoring of critical piping and fuel delivery systems. A variety of commercial applications also exist in bio-medical engineering for monitoring human heart health, cranial brain pressure and aiding in the development of mechanical heart valves. Equipment manufacturers for compressors, pumping systems, and valve actuating devices interested in lowering radiant noise levels will also benefit from the new sensor product.

Keywords:
PVDF sensors, PVDF sensors, Fluid-filled pipes, Modeling and Simulation, sensor accuracy and error, Structural Acoustics, interior fluidborne sound level, Finite Elements.

The Phase II base period of this project will focus on developing a hardened version of an externally mounted PVDF wire sensor measurement system and experimentally demonstrating and validating its use for determining internal pressure levels for realistic piping systems. A closed circuit piping test rig will be designed and fabricated at Virginia Tech using typical piping components including a pump, valves, bends, flanges, tees, gaskets, accumulators, and hangers. Multiple sources to create fluid-borne and structure-borne sound energy will be included. Enhanced structural pipe excitation will be accomplished using externally mounted shakers. Omnidirectional sound sources will also be utilized to widen the frequency range. Finite Element modeling of piping components will be used as needed to support the design and development of improved PVDF pressure sensor systems. A hardened PVDF sensor and associated electronics will be constructed. Phase II Option I will focus on developing performance estimates of the PVDF sensor and designing and building prototype installation and calibration tools. Phase II Option II extends the work plan and focuses on pre-commercialization activities for a production-level PVDF sensor, installation, and calibration tools. In Phase III, full product manufacturing, validation and distribution will be provided to both government and industry.

Benefit:
Potential government applications include hydraulics and piping systems on Naval submarines and surface ships. The private sector opportunities include Bio-Medical for control systems to monitor mechanical heart valves: Aerospace for mission critical fluid delivery systems; Manufacturing Industry for compressors and pumps; Nuclear power industry; and Fuels and Energy industries for gas-pipeline delivery performance.

Keywords:
piezo-electric Polyvinylidene Fluoride (PVDF), Piping systems, Navy submarines, externally mounted wire transducer, acoustic sound pressure measurement, Finite Element Analysis