Mechanical Engineering PhD Thesis Defense by Talha Irfan Khan

KOÇ UNIVERSITY

GRADUATE SCHOOL OF SCIENCES & ENGINEERING

MECHANICAL ENGINEERING

PhD THESIS DEFENSE BY TALHA IRFAN KHAN

Title: Design Analysis and Development of a Miniature Blood Pump

Speaker: Talha Irfan Khan

Time: July, 27,2018 at 2:00 PM

Place: MARC Engineering B203

Koç University

Rumeli Feneri Yolu

Sariyer, Istanbul

Thesis Committee Members:

Prof. Dr. İsmail Lazoğlu (Advisor, Koç University)

Prof. Dr. Metin Muradoğlu (Koç University)

Prof. Dr. Deniz Süha Küçükaksu (Başkent Unıvercity)

Assoc. Prof. Dr. Kerem Pekkan (Koç University)

Asst. Prof. Dr. Fethi Okyar (Yeditepe University)

Abstract:

Congenital Heart Disease (CHD) is one of the leading cause of infant death around the world. According to American Heart Association (AHA) 9.3 out of 1000 live births in Asia are affected from CHD. In adults, Mechanical Circulatory Support (MCS) has emerged as a life-saving device. Due to size limitations and nature of CHD, the adult devices are not suitable for pediatric patients. Thus, there is a need for a miniature MCS device implantable to pediatric patients. This study aims to develop a novel blood pump for CHD patients. The device proposed in this thesis is a novel shrouded impeller axial flow pump. This type of design has never been tried experimentally in blood pumps before.

The impeller and diffuser blade angles of blood pump were obtained by performing 2D velocity triangles analysis. Computational Fluid Dynamics (CFD) analysis has been used to predict the hydraulic performance and to visualize the flow field within the pump. A number of impeller and diffuser designs with varying geometric parameters were analyzed to come up with the Prototype I of shrouded impeller pediatric ventricular assist device (SIP-VAD). Regions of high shear stress indicated the possible areas causing blood damage. A benchtop model of Prototype I was manufactured to verify the CFD results. The impeller, inducer, and diffuser were manufactured using rapid prototyping method. Arc-shaped magnets were installed at the outer periphery of the impeller and 3-phase, brushless direct current (BLDC) motor principle was used to rotate the impeller. Comparison of experimental and CFD results revealed the reliability of the CFD model for further design modification.

CFD based blood damage analysis was performed using Eulerian stress and strain-based models. The verification of this model was performed by comparing results with the in vitro blood test. Different power law functions were used to find the best model for our design. Results show the strain-based model to be more accurate in predicting blood damage. Based on this model design improvements were made in Prototype I. Further CFD analysis was performed to finalize Prototype II design. The benchtop experimental setup was manufactured using high precision 5-axis machine tool. The in vitro hydraulic and blood test were performed. The blood damage results revealed an acceptable level of blood damage in the proposed design. Therefore, it is shown that the used of shrouded impeller design can lead to good results in miniature blood pumps.