Naval Surface Warfare Center

About: Naval Surface Warfare Center is a research topic. Over the lifetime, 235 publications have been published within this topic receiving 1501 citations. The topic is also known as: NSWC.

Control of cascaded multi-level inverters

Abstract: A new type of multilevel inverter is introduced which is created by cascading two three-phase three-level inverters using the load connection, but requires only one dc voltage source. This new inverter can operate as a seven-level inverter and naturally splits the power conversion into a higher-voltage lower-frequency inverter and a lower-voltage higher-frequency inverter. This type of system presents particular advantages to Naval ship propulsion systems which rely on high power quality, survivable drives. New control methods are described involving both joint and separate control of the individual three-level inverters. Simulation results demonstrate the effectiveness of both controls. A laboratory set-up at the Naval Surface Warfare Center power electronics laboratory was used to validate the proposed joint-inverter control. Due to the effect of compounding levels in the cascaded inverter, a high number of levels are available resulting in a voltage THD of 9% (without filtering).

Full Power Test of a 36.5 MW HTS Propulsion Motor

Abstract: This paper discusses the full-power testing of a 36.5 MW High Temperature Superconductor (HTS) propulsion motor at the Navy's Land Based Test Site (LBTS) located in Philadelphia, PA. This motor was developed under funding from the Office of Naval Research and passed no-load factory testing at Philadelphia in March 2007. The Naval Surface Warfare Center (Carderock Division - Philadelphia site) designed and installed a test facility at LBTS to support full-power/full-torque testing of the HTS motor delivered to the Navy in 2007. The facility, test plan and full-power and full-torque test results of the HTS propulsion motor are presented. These test results provide the final substantiation that this technology is ready for integration in to a Navy electric drive combatant.

Shielding effectiveness measurements using mode-stirred chambers: a comparison of two approaches

Abstract: Two methodologies for performing shielding effectiveness measurements using mode-stirred chambers are presented. The first method, which utilizes the traditional single (discrete) frequency approach, in use at the US Naval Surface Warfare Center (NSWC) for several years, is referred to as the discrete frequency method. The discrete frequency method, as the name implies, involves testing only one frequency at a time. By contract, the second method utilizes broadband noise sources and can measure shielding effectiveness over large bandwidths with high resolution in short periods of time. The second method is referred to as the noise method. >

The Response of Surface Ships to Underwater Explosions.

Abstract: : This report is a summary of technical information gathered by the author during an attachment to the Underwater Explosions Research Department (UERD) of the Naval Surface Warfare Center (NSWC) Carderock Division from April 1993 to July 1994 The report covers aspects of UERD's work in the area of: ship shock trials, response of surface ships to underwater explosions, computer modelling of surface ship responses and other technical information culled from the general literature

Fiber optic structural health monitoring system: rough sea trials testing of the RV Triton

Abstract: Systems Planning and Analysis, Inc., under sponsorship from the United States Navy, Office of Naval Research (ONR), has developed a structural health monitoring system for large-scale structures, based on fiber Bragg grating (FBG) sensors. The application of this new structural health monitoring system to US Navy vessels will reduce maintenance costs by allowing for scheduling of need-based maintenance, increase fleet operational availability, and ship survivability by providing ship operators real-time information concerning the state of the ship structure. Central to the monitoring system is an instrumentation unit capable of detecting signals from hundreds of FBG sensors with sampling rates approaching 2 kHz. The instrumentation is based on SPA's proprietary Digital Spatial Wavelength Domain Multiplexing (DSWDM) technology developed under this effort. DSWDM technology is electro-optics based and has been shown to provide significantly higher sampling rates than comparative FBG interrogation technologies. The baseline system interrogates more than 120 sensors along eight fiber channels. The prototype High Speed-Fiber Optic Interrogation System (HS-FOIS) also possesses a number of advantages intrinsic to optical fiber sensors as compared to conventional strain sensor systems. These advantages include extremely low installed weight and volume, immunity to electromagnetic interference and corrosive environments, and low signal attenuation and drift. This paper describes the installation and testing of a large-scale fiber optic sensor network on the British Trimaran Research Vessel (RV) Triton. In this on-going project with the Naval Surface Warfare Center, Carderock Division (NSWCCD) and the British Defence Science and Technology Laboratory (formerly DERA), Systems Planning and Analysis, Inc. (SPA) recently completed the installation and at-sea testing of an integrated hardware/software structural monitoring system. The rough sea trials of the RV Triton was conducted in early February 2002 in the North Atlantic. This paper describes the fiber optic Bragg grating sensor network comprising of 51 sensors, the interrogating system, and the processing algorithms used to simultaneously record strain data at both high- and low-speed frequencies, including triggering of the high-speed channels. This paper also details the sensor layout and installation process with emphasis on lessons learned during this procedure. The test procedure and sample data results are presented. Finally, conclusions on the presented data and implications of the structural health monitoring system for future naval vessels are discussed.