Propulsion Development Engineer - Fluid/ Thermal

Portalsystems; Bothell (WA); On-site; USD 110,000 - 170,000; Full time

Job summary

Portal Space Systems in Bothell, WA is seeking a Fluid/Thermal-focused Propulsion Engineer to advance thruster, feed system, and tank development. You will perform high-fidelity CFD and thermal analyses to inform design trades from concept to flight hardware.

You will build fluid network models for component sizing, support test campaigns, and collaborate with propulsion and analysis teams to reduce risk and accelerate hardware decisions.

Qualifications

• Bachelor’s or Master’s degree in Mechanical or Aerospace Engineering or related field.
• Experience developing complex CFD models and reduced order fluid/thermal hand calcs.
• Experience communicating analysis assumptions, results, and design implications.

Responsibilities

• Develop high fidelity CFD models to support HEX thruster and propellant tank development.
• Model complex fluid behavior, including multiphase flow, phase change, conjugate heat transfer, and tank slosh.
• Build fluid network models of feed systems for component sizing and controls development.
• Complete first order hand calcs for simple problems and quick answers.
• Support propulsion test campaigns with pre-test predictions, instrumentation planning, and post-test data reduction and model correlation.
• Predict transient temperature distributions internal to the HEX Thruster and design thermal control approaches.

Skills

Fluid mechanics

Thermodynamics

Heat transfer

CFD modeling

Technical communication

Education

Bachelor's or Master’s in Mechanical or Aerospace Engineering

Tools

NX

STAR-CCM+

GFSSP

Linux

Job description

Portal Space Systems is on a mission to expand humanity’s freedom of movement in space. We’re building the spacecraft that makes that mission possible. From our Bothell, WA headquarters, we design vehicles with the maneuverability, resilience, and adaptability needed for the next era of orbital operations. Every system we build is in service of a simple idea: space should be more accessible, responsive, and capable. Joining Portal means stepping into a team that believes in bold engineering, fast iteration, and the power of small groups to change what’s possible. If you want your work to directly shape the future of in-space mobility, join us.

About the Role

We are hiring a Fluid/Thermal-focused Propulsion Engineer to advance thruster, feed system, and tank development. This role is responsible for high fidelity CFD (multiphase, phase change, conjugate heat transfer, slosh) and thermal analysis, developing fluid network models, and supporting component sizing across the feed system. This position works closely with fellow propulsion engineers and analysis experts to inform design trades, predict performance, and drive hardware development from conceptual trades through qualified hardware and flight.

Primary Responsibility – Fluid Analysis

• Develop high fidelity CFD models to support HEX Thruster and propellant tank development
• Model complex fluid behavior, including multiphase flow, phase change, and conjugate heat transfer, and tank slosh
• Build fluid network models of feed systems and utilize these for component sizing and controls development
• Complete first order hand calcs for simple problems and quick answers
• Support propulsion test campaigns with pre-test predictions, instrumentation planning, and post-test data reduction and model correlation

Secondary Responsibility – Thermal Analysis

• Predict transient temperature distributions internal to the HEX Thruster as driven by radiation in, re-radiation out, conduction internal to the thruster, and conduction to the bus
• Identify and design thermal control approaches of the thruster, including radiation absorption design, re-radiation mitigation, and conduction paths

What You Bring To Portal

• Strong foundation in fluid mechanics, thermodynamics, and heat transfer with the ability to apply first principles reasoning and quickly learn new modeling approaches.
• Ability to identify, within the role’s scope, high-impact technical problems and focus analysis efforts where they can most effectively reduce risk, improve performance, and accelerate hardware decisions
• Propensity to solicit and provide peer review, clearly and concisely document results, and communicate implications for the associated hardware

Basic Qualifications

• Bachelor’s or Master’s degree in Mechanical Engineering, Aerospace Engineering, related field or equivalent.
• Experience developing complex CFD models and reduced order fluid/thermal hand calcs.
• Experience communicating analysis assumptions, results, and design implications.

Preferred Qualifications

• Proficiency with NX, STAR-CCM+, GFSSP, and Linux
• Experience with multiphase, conjugate heat transfer, and transient CFD modeling
• Experience with high geometric fidelity thermal modeling
• Experience using test data to correlate analytical models

This position may involve access to technical data and defense-related materials controlled under the International Traffic in Arms Regulations (ITAR).

Eligibility to access ITAR-controlled items requires that candidates be U.S. persons, which includes U.S. citizens, lawful permanent residents, and other protected individuals as defined by U.S. law.

Employment is contingent upon verification of ITAR eligibility and, where applicable, obtaining any required export authorization or license.

Equal Opportunity Statement

All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual.

Voluntary Self-Identification

For government reporting purposes, we ask candidates to respond to the below self-identification survey.Completion of the form is entirely voluntary. Whatever your decision, it will not be considered in the hiringprocess or thereafter. Any information that you do provide will be recorded and maintained in aconfidential file.

As set forth in Portal Space Systems’s Equal Employment Opportunity policy,we do not discriminate on the basis of any protected group status under any applicable law.

If you believe you belong to any of the categories of protected veterans listed below, please indicate by making the appropriate selection.As a government contractor subject to the Vietnam Era Veterans Readjustment Assistance Act (VEVRAA), we request this information in order to measurethe effectiveness of the outreach and positive recruitment efforts we undertake pursuant to VEVRAA. Classification of protected categoriesis as follows:

A "disabled veteran" is one of the following: a veteran of the U.S. military, ground, naval or air service who is entitled to compensation (or who but for the receipt of military retired pay would be entitled to compensation) under laws administered by the Secretary of Veterans Affairs; or a person who was discharged or released from active duty because of a service-connected disability.

A "recently separated veteran" means any veteran during the three-year period beginning on the date of such veteran's discharge or release from active duty in the U.S. military, ground, naval, or air service.

An "active duty wartime or campaign badge veteran" means a veteran who served on active duty in the U.S. military, ground, naval or air service during a war, or in a campaign or expedition for which a campaign badge has been authorized under the laws administered by the Department of Defense.

An "Armed forces service medal veteran" means a veteran who, while serving on active duty in the U.S. military, ground, naval or air service, participated in a United States military operation for which an Armed Forces service medal was awarded pursuant to Executive Order 12985.

Voluntary Self-Identification of Disability

Form CC-305

Page 1 of 1

OMB Control Number 1250-0005

Expires 04/30/2026

Why are you being asked to complete this form?

We are a federal contractor or subcontractor. The law requires us to provide equal employment opportunity to qualified people with disabilities. We have a goal of having at least 7% of our workers as people with disabilities. The law says we must measure our progress towards this goal. To do this, we must ask applicants and employees if they have a disability or have ever had one. People can become disabled, so we need to ask this question at least every five years.

Completing this form is voluntary, and we hope that you will choose to do so. Your answer is confidential. No one who makes hiring decisions will see it. Your decision to complete the form and your answer will not harm you in any way. If you want to learn more about the law or this form, visit the U.S. Department of Labor’s Office of Federal Contract Compliance Programs (OFCCP) website at www.dol.gov/ofccp .

How do you know if you have a disability?

A disability is a condition that substantially limits one or more of your “major life activities.” If you have or have ever had such a condition, you are a person with a disability. Disabilities include, but are not limited to:

• Alcohol or other substance use disorder (not currently using drugs illegally)
• Autoimmune disorder, for example, lupus, fibromyalgia, rheumatoid arthritis, HIV/AIDS
• Blind or low vision
• Cancer (past or present)
• Cardiovascular or heart disease
• Celiac disease
• Cerebral palsy
• Deaf or serious difficulty hearing
• Diabetes
• Disfigurement, for example, disfigurement caused by burns, wounds, accidents, or congenital disorders
• Epilepsy or other seizure disorder
• Gastrointestinal disorders, for example, Crohn's Disease, irritable bowel syndrome
• Intellectual or developmental disability
• Mental health conditions, for example, depression, bipolar disorder, anxiety disorder, schizophrenia, PTSD
• Missing limbs or partially missing limbs
• Mobility impairment, benefiting from the use of a wheelchair, scooter, walker, leg brace(s) and/or other supports
• Nervous system condition, for example, migraine headaches, Parkinson’s disease, multiple sclerosis (MS)
• Neurodivergence, for example, attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder, dyslexia, dyspraxia, other learning disabilities
• Partial or complete paralysis (any cause)
• Pulmonary or respiratory conditions, for example, tuberculosis, asthma, emphysema
• Short stature (dwarfism)
• Traumatic brain injury

PUBLIC BURDEN STATEMENT: According to the Paperwork Reduction Act of 1995 no persons are required to respond to a collection of information unless such collection displays a valid OMB control number. This survey should take about 5 minutes to complete.