Frank Kushner Avatar

Frank Kushner

Consulting Engineer

Vibrations & Acoustics

experience

Engineering Consultant  
Frank Kushner Consulting, February 2004 to Present, Delmont, Pennsylvania United States
(Industrial Turbomachinery)
Engineering consulting in rotating equipment including expert witness reports and testimony. Specializing in vibrations and acoustics design aspects and root cause failure analysis. Member A.S.M.E. # 673004 and Vibration Institute #01-3442

Senior Consulting Engineer  
Elliott Company, June 1969 to February 2004

Senior Consulting Engineer § Extensive knowledge of important aspects of vibration/noise in axial and centrifugal turbomachinery. § Utilize abilities to prioritize most likely causes of vibration and/or noise and propose cost-effective solutions. § Review new/modified designs of machinery and components to preclude problems, with optimum conservative safety and reliability. § Conduct modal analysis and other tests using rigs or actual machines for lab, shop and field data; correlate with calculations and use to solve problems (recently designed, procured components and supervised assembly of a gas seal test rig that has run successfully from initiation). § Assist in sales and warranty issues by providing comments, guarantee recommendations, documentation, and references for meetings with customers and their consultants. § Review test and analytical results by others for accurate correlation and problem solutions, including those at the rotor at-speed balancing facility. § Provide internal technical reports and peer-reviewed technical papers for external publication (information attached for eight most recent papers). § Maintain knowledge of related fields: aerodynamics and stress analysis, including finite element and CFD techniques; properties of materials and fracture mechanics for utilization in cause and effect analysis. Remain cognizant of state-of-the art techniques and investigative tools.

education

Rensselaer Polytechnic Institute  
MSME, Mechanical Engineering, Jan, 1965 to Jan, 1967


Indiana Institute of Technology  
BSME, Mechanical Engineering, Jan, 1961 to Jan, 1965


Certifications

  • Professional Engineer
    PA (PE-016762-E)

patents

Method for preventing one-cell stall in bladed discs  (5832606)    
Inventors: Francis Kushner.  Issued September 16, 1997  in United States

A method for preventing one-cell rotating stall initiated by a bladed disc having a plurality of blades including the steps of identifying a one-cell stall condition and modifying one or more blades to force the bladed disc into at least a two-cell stall pattern. This can be accomplished by modifying the spacing between the blades to force the bladed disc into at least a two-cell stall pattern. Alternatively, at least one of the blades can be geometrically modified so as to force the bladed disc into at least a two-cell stall pattern.

Turbomachinery stationary vane arrangement for disk and blade excitation reduction and phase cancellation  (9,581,034)    
Inventors: Francis Kushner, Brian Pettinato.  Issued March 14, 2013  in United States

A turbomachine includes a plurality of rotating blades adjacent to a plurality of stationary vanes attached to a stationary casing. Stationary vanes are spaced apart circumferentially with equal spacing around an inner perimeter of the casing. Optionally, stationary vanes are offset radially and/or circumferentially. Stationary vanes may alternate with leading and/or trailing edges at different distances from the rotating blades. In one embodiment, stationary vanes have tapered leading and/or trailing edge angles to homogenize flow and reduce stator wake excitation, flow excitation, and acoustic excitation due to interaction with spinning modes of acoustic pressure pulsations at rotating blade passing frequency. Tapered trailing edges are arranged such that they are inclined at mutually opposing angles to reduce rotor blade and/or disk excitation by: a) homogenizing the successive wakes within the flow stream, and b) reducing the effect of vortices shed-off the stationary vanes on acoustic modes of the gas within the casing.

publications

Disc Vibration – Rotating Blade and Stationary Vane Interaction     
Published by (ASME Journal of Mechanical Design)
Authors: Frank Kushner.  Published July 01, 1980

Describes 1976 discovery of Interaction Resonance for Bladed Disks (Includes equations later termed by others as “Safe Diagrams” and also “Interference Diagrams”)

Rotating Component Modal Analysis And Resonance Avoidance Recommendations – An Update     
Published by (Texas A&M University; Proceedings of the 42nd Turbomachinery Symposium, Turbomachinery Laboratory)
Authors: Kushner, F., Shurina, J., Strickland, R. A.  Published October 01, 2013

Rotating disk and blade fatigue failures are usually a low percentage of failures i n most machinery types, but other than coupling / shaft end failures remain some of the most problematic for extensive repairs. High -cycle fatigue failures of rotating disks and blades are not common in most machinery types, but when they occur, they requi re extensive repairs and resolution can be problematic. This paper is an update of the tutorial given at the 2004 Turbomachinery Symposium focusing on high -cycle fatigue failures in steam turbines, centrifugal and axial gas compressors in refineries and pr ocess plants. The failure theories and many of the descriptions for cases given in 2004 have been updated to include blade resonance concerns for potential flow as well as vane and blade wake effects. Disk vibratory modes can be of concern in many machines , but of little concern in others as will be explained. In addition, vibratory modes are included where blades are coupled via communication with the main disk. Over the past decade, fluid -structure -interaction computational methods and modal testing have improved and have been applied to failure theories and problem resolution in the given cases. There is also added information on the effects of mistuning blades and disks, some beneficial and some with serious concerns for increased resonant amplification. Finally, knowledge about acoustic pressure pulsation excitation, particularly for centrifugal impellers at rotating blade passing frequency, has been greatly expanded. A review of acoustics calculations for failure prevention, mainly for high -pressure app lications is covered here.