Application Of LDV Profile Sensor Technology For Velocity Determination In Small Axial Gaps

Abstract

In development of Ventricular Assist Devices (VADs), Computational Fluid Dynamics (CFD) have arise as a powerful tool to gain insights on flow topologies within rotary blood pumps. Information regarding flow patterns and shear-stress distributions is of enormous importance, since flow induced blood damage as well as platelet activation is at-tributed to shear rates. Although methods for verification of numerical results are available, a lack of experimental validation is recognizable. To enable an experimental validation (i) hydraulic properties as well as flow patterns need to be preserved and (ii) a non-intrusive optical measurement technique needs to be capable of resolving flow topolo-gies appearing in rotary blood pumps. In this paper references to address (i) are provided and the focus is placed on (ii) by presenting a methodology to resolve flow topologies by usage of LDV Profile Sensor technology. This paper serves as a feasibility study and represents a preliminary stage towards actual optical measurements with rotary blood pumps. Therefore, a test bench with facilitated optical accessibility compared to Ventricular Assist Devices as well as operating conditions are introduced. Increased attention is dedicated to evaluation of measurement data by means of choosing a suitable procedure. Therefore, commonly used 2D-histograms for LDV raw data evaluation are compared to the method of Gaussian Kernel Density Estimation (Gaussian KDE). Subsequently, pre-processed raw data is further evaluated with a specially tailored Velocity Profile Validation Algorithm and determined circumferen-tial velocity profiles are discussed. In summary, herein presented feasibility study is deemed successful and LDV Pro-file Sensor technology is capable of resolving flow topologies within small gaps as they appear in Ventricular Assist Devices. Thus, LDV Profile Sensor technology may improve development of rotary blood pumps.